Part V - Airworthiness Manual Chapter 525 - Transport Category Aeroplanes

Canadian Aviation Regulations (CARs) 2017-2

Preamble

SUBCHAPTERS

  • A (525.1-525.2),
  • B (525.21-525.255),
  • C (525.301-525.581),
  • D (525.601-525.899),
  • E (525.901-525.1207),
  • F (525.1301-525.1461),
  • G (525.1501-525.1587)
  • H (525.1701-525.1733)

APPENDICES

A, B, C, D, E, F, G, H, I, J, L, M, N

(2001/06/01; no previous version)

SUBCHAPTER A GENERAL

525.1 Applicability
  1. (a) This Chapter sets out airworthiness standards for the issuance of type certificates and changes to type certificates, for transport category aeroplanes.
    (amended 2009/12/01; previous version)
  2. (b) Reserved.
    (amended 2009/12/01; previous version)

(Change 525-3 (91-11-01))
(Change 525-7 (96-09-30))
(Change 525-8)

525.2 Special Retroactive Requirements

The following special retroactive requirements are applicable to an aeroplane for which the standards referenced in the type certificate, or in an equivalent document based on which the Minister has issued a Certificate of Airworthiness, predate the sections of the Code of Federal Regulations of the United States of America, Title 14, Chapter 1, Part 25, which are specified hereafter:

FAR:

The following special retroactive requirements are applicable to an airplane for which the regulations referenced in the type certificate predate the sections specified below:

  1. (a) Irrespective of the date of application, each applicant for a supplemental type certificate (or an amendment to a type certificate) involving an increase in passenger seating capacity to a total greater than that for which the aeroplane has been type certificated must show that the aeroplane concerned meets the requirements of:
    1. (1) FAR sections 25.721(d), 25.783(g), 25.785(c), 25.803(c)(2) through (9), 25.803(d) and (e), 25.807(a), (c), and (d), 25.809(f) and (h), 25.811, 25.812, 25.813(a), (b). and (c), 25.815, 25.817, 25.853(a) and (b), 25.855(a), 25.993(f) and 25.1359(c), in effect on October 24, 1967, and
      (amended 2009/12/01; previous version)
    2. (2) FAR sections 25.803(b) and (c)(1) in effect on April 23, 1969.
  2. (b) Irrespective of the date of application, each applicant for a supplemental type certificate (or an amendment to a type certificate) for an aeroplane manufactured after October 16, 1987, must show that the aeroplane meets the requirements of FAR 25.807(c)(7) in effect on July 24, 1989.

    Note: The requirements of FAR 25.807(c)(7), in effect on July 24, 1989, are those published by the Federal Aviation Administration of the United States of America at amendment 25-67.
  3. (c) Compliance with subsequent revisions to the sections specified in paragraph (a) or (b) above may be elected or may be required in accordance with Division IV of Part V, Subpart 21 of the Canadian Aviation Regulations.
    (amended 2009/12/01; previous version)

FAR:

(c) Compliance with subsequent revisions to the sections specified in paragraph (a) or (b) above may be elected in accordance with §21.101(a)(2) of this chapter or may be required in accordance with §21.101(b) of this chapter.

(Change 525-3 (91-11-01))
(Change 525-8)

SUBCHAPTER B FLIGHT - GENERAL

525.21 Proof of Compliance
  1. (a) Each requirement of this subchapter must be met at each appropriate combination of weight and centre of gravity within the range of loading conditions for which certification is requested. This must be shown:
    1. (1) By tests upon an aeroplane of the type for which certification is requested, or by calculations based on, and equal in accuracy to, the results of testing; and
    2. (2) By systematic investigation of each probable combination of weight and centre of gravity, if compliance cannot be reasonably inferred from combinations investigated.
  2. (b) (Reserved)
  3. (c) The controllability, stability, trim, and stalling characteristics of the aeroplane must be shown for each altitude up to the maximum expected in operation.
  4. (d) Parameters critical for the test being conducted, such as weight, loading (centre of gravity and inertia), airspeed, power, and wind, must be maintained within acceptable tolerances of the critical values during flight testing.
  5. (e) If compliance with the flight characteristics requirements is dependent upon a stability augmentation system or upon any other automatic or power-operated system, compliance must be shown with 525.671 and 525.672.
  6. (f) In meeting the requirements of 525.105(d), 525.125, 525.233, and 525.237, the wind velocity shall be measured at a height of 10 metres above the surface, or corrected for the difference between the height at which the wind velocity is measured and the 10-metre height.
    (amended 2008/10/30; previous version)
  7. (g) The requirements of this subchapter associated with icing conditions apply only if the applicant is seeking certification for flight in icing conditions.
    (amended 2008/10/30; no previous version)
    1. (1) Each requirement of this subchapter, except 525.121(a), 525.123(c), 525.143(b)(1) and (2), 525.149, 525.201(c)(2), 525.239, and 525.251(b) through (e), shall be met in icing conditions. Section 525.207(c) and (d) shall be met in the landing configuration in icing conditions, but need not be met for other configurations. Compliance shall be shown using the ice accretions defined in Appendix C, assuming normal operation of the aeroplane and its ice protection system in accordance with the operating limitations and operating procedures established by the applicant and provided in the Aeroplane Flight Manual.
      (effective 2013/02/01)
    2. (2) No changes in the load distribution limits of 525.23, the weight limits of 525.25 (except where limited by performance requirements of this subchapter), and the center of gravity limits of 525.27, from those for non-icing conditions, are allowed for flight in icing conditions or with ice accretion.
      (amended 2008/10/30)

(Change 525-3 (91-11-01))

525.23 Load Distribution Limits
  1. (a) Ranges of weights and centres of gravity within which the aeroplane may be safely operated must be established. If a weight and centre of gravity combination is allowable only within certain load distribution limits (such as spanwise) that could be inadvertently exceeded, these limits and the corresponding weight and centre of gravity combinations must be established.
  2. (b) The load distribution limits may not exceed:
    1. (1) The selected limits;
    2. (2) The limits at which the structure is proven; or
    3. (3) The limits at which compliance with each applicable flight requirement of this subchapter is shown.
525.25 Weight Limits
  1. (a) Maximum weights. Maximum weights corresponding to the aeroplane operating conditions (such as ramp, ground or water taxi, take-off, en route, and landing) environmental conditions (such as altitude and temperature), and loading conditions (such as zero fuel weight, centre of gravity position and weight distribution) must be established so that they are not more than:
    1. (1) The highest weight selected by the applicant for the particular conditions; or
    2. (2) The highest weight at which compliance with each applicable structural loading and flight requirement is shown, except that for aeroplanes equipped with standby power rocket engines the maximum weight must not be more than the highest weight established in accordance with Appendix E of this chapter; or
    3. (3) The highest weight at which compliance is shown with the certification requirements of chapter 516, Subchapter A of this manual.
  2. (b) Minimum weight. The minimum weight (the lowest weight at which compliance with each applicable requirement of this chapter is shown) must be established so that it is not less than:
    1. (1) The lowest weight selected by the applicant;
    2. (2) The design minimum weight (the lowest weight at which compliance with each structural loading condition of this chapter is shown); or
    3. (3) The lowest weight at which compliance with each applicable flight requirement is shown.

(Change 525-2 (89-01-01))

525.27 Centre of Gravity Limits

The extreme forward and the extreme aft centre of gravity limitations must be established for each practicably separable operating condition. No such limit may lie beyond:

  1. (a) The extremes selected by the applicant;
  2. (b) The extremes within which the structure is proven; or
  3. (c) The extremes within which compliance with each applicable flight requirement is shown.
525.29 Empty Weight and Corresponding Centre of Gravity
  1. (a) The empty weight and corresponding centre of gravity must be determined by weighing the aeroplane with:
    1. (1) Fixed ballast;
    2. (2) Unusable fuel determined under 525.959; and
    3. (3) Full operating fluids, including:
      1. (i) Oil;
      2. (ii) Hydraulic fluid; and
      3. (iii) Other fluids required for normal operation of aeroplane systems, except potable water, lavatory precharge water, and fluids intended for injection in the engine.
  2. (b) The condition of the aeroplane at the time of determining empty weight must be one that is well defined and can be easily repeated.

(Change 525-3 (91-11-01))

525.31 Removable Ballast

Removable ballast may be used in showing compliance with the flight requirements of this subchapter.

525.33 Propeller Speed and Pitch Limits
  1. (a) The propeller speed and pitch must be limited to values that will ensure:
    1. (1) Safe operation under normal operating conditions; and
    2. (2) Compliance with the performance requirements in 525.101 through 525.125.
  2. (b) There must be a propeller speed limiting means at the governor. It must limit the maximum possible governed engine speed to a value not exceeding the maximum allowable r.p.m.
  3. (c) The means used to limit the low pitch position of the propeller blades must be set so that the engine speed does not exceed 103 percent of the maximum allowable engine r.p.m. or 99 percent of an approved maximum overspeed whichever is greater with:
    1. (1) The propeller blades at the low pitch limit and governor inoperative;
    2. (2) The aeroplane stationary under standard atmospheric conditions with no wind; and
    3. (3) The engines operating at the take-off manifold pressure limit for reciprocating engine powered aeroplanes or the maximum take-off torque limit for turbopropeller engine-powered aeroplanes.

(Change 525-3 (91-11-01))

Performance
525.101 General
  1. (a) Unless otherwise prescribed, aeroplanes must meet the applicable performance requirements of this subchapter for ambient atmospheric conditions and still air.
  2. (b) The performance, as affected by engine power or thrust, must be based on the following relative humidities:
    1. (1) For turbine engine powered aeroplanes, a relative humidity of:
      1. (i) 80 percent, at and below standard temperatures; and
      2. (ii) 34 percent, at and above standard temperatures plus 50 degrees F.
      3. Between these two temperatures, the relative humidity must vary linearly.
    2. (2) For reciprocating engine powered aeroplanes, a relative humidity of 80 percent in a standard atmosphere. Engine power corrections for vapour pressure must be made in accordance with the following table:
Altitude
H (ft.)
Vapour Pressure "e"
(in. Hg.) (mb)
Specific Humidity W
(lb. moisture per lb. dry air)
Density Ratio
s =r /0.0023769
0 0.403 (13.64) 0.00849 0.99508
1,000 0.354 (11.98) 0.00773 0.96672
2,000 0.311 (10.53) 0.00703 0.93895
3,000 0.272 ( 9.21) 0.00638 0.91178
4,000 0.238 ( 8.06) 0.00578 0.88514
5,000 0.207 ( 7.00) 0.00523 0.85910
6,000 0.1805 ( 6.11) 0.00472 0.83361
7,000 0.1566 ( 5.30) 0.00425 0.80870
8,000 0.1356 ( 4.59) 0.00382 0.78434
9,000 0.1172 ( 3.97) 0.00343 0.76053
10,000 0.1010 ( 3.42) 0.00307 0.73722
15,000 0.0463 ( 1.57) 0.001710 0.62868
20,000 0.01978 ( 0.67) 0.000896 0.53263
25,000 0.00778 ( 0.26) 0.000436 0.44806
  1. (c) The performance must correspond to the propulsive thrust available under the particular ambient atmospheric conditions, the particular flight condition, and the relative humidity specified in paragraph (b) of this section. The available propulsive thrust must correspond to engine power or thrust, not exceeding the approved power or thrust, less:
    1. (1) Installation losses; and
    2. (2) The power or equivalent thrust absorbed by the accessories and services appropriate to the particular ambient atmospheric conditions and the particular flight condition.
  2. (d) Unless otherwise prescribed, the applicant must select the take-off, en route, approach, and landing configurations for the aeroplane.
  3. (e) The aeroplane configurations may vary with weight, altitude, and temperature, to the extent they are compatible with the operating procedures required by paragraph (f) of this section.
  4. (f) Unless otherwise prescribed, in determining the accelerate-stop distances, take-off flight paths, take-off distances, and landing distances, changes in the aeroplane's configuration, speed, power, and thrust, must be made in accordance with procedures established by the applicant for operation in service.
  5. (g) Procedures for the execution of balked landings and missed approaches associated with the conditions prescribed in 525.119 and 525.121(d) must be established.
  6. (h) The procedures established under paragraphs (f) and (g) of this section must:
    1. (1) Be able to be consistently executed in service by crews of average skill;
    2. (2) Use methods or devices that are safe and reliable; and
    3. (3) Include allowance for any time delays, in the execution of the procedures, that may reasonably be expected in service.
  7. (i) The accelerate-stop and landing distances prescribed in 525.109 and 525.125, respectively, must be determined with all the aeroplane wheel brake assemblies at the fully worn limit of their allowable wear range.

(Change 525-8)

525.103 Stall Speed
(amended 2003/11/10; previous version)
  1. (a) The reference stall speed, VSR, is a calibrated airspeed defined by the applicant. VSR may not be less than a 1-g stall speed. VSR is expressed as:
    (amended 2003/11/10; previous version)

Stall speed formula

Where:
(amended 2003/11/10; previous version)

VCLMAX= Calibrated airspeed obtained when the load factor-corrected lift coefficient

Stall speed formula

is first a maximum during the manoeuvre prescribed in paragraph (c) of this section. In addition, when the manoeuvre is limited by a device that abruptly pushes the nose down at a selected angle of attack (e.g., a stick pusher), VCLMAX may not be less than the speed existing at the instant the device operates;

nZW= Load factor normal to the flight path at VCLMAX

W= Aeroplane gross weight;

S= Aerodynamic reference wing area; and

q= Dynamic pressure.

  1. (b) VCLMAX is determined with:
    (amended 2003/11/10; previous version)
    1. (1) Engines idling, or, if that resultant thrust causes an appreciable decrease in stall speed, not more than zero thrust at the stall speed;
      (amended 2003/11/10; previous version)
    2. (2) Propeller pitch controls (if applicable) in the take-off position;
      (amended 2003/11/10; previous version)
    3. (3) aeroplane in other respects (such as flaps, landing gear and ice accretions) in the condition existing in the test or performance standard in which VSR is being used;
      (amended 2008/10/30; previous version)
    4. (4) The weight used when VSR is being used as a factor to determine compliance with a required performance standard;
      (amended 2003/11/10; previous version)
    5. (5) The center of gravity position that results in the highest value of reference stall speed; and
      (amended 2003/11/10; previous version)
    6. (6) The aeroplane trimmed for straight flight at a speed selected by the applicant, but not less than 1.13VSR and not greater than 1.3VSR.
      (amended 2003/11/10; previous version)
  2. (c) Starting from the stabilized trim condition, apply the longitudinal control to decelerate the aeroplane so that the speed reduction does not exceed one knot per second.
    (amended 2003/11/10; no previous version)
  3. (d) In addition to the requirements of paragraph (a) of this section, when a device that abruptly pushes the nose down at a selected angle of attack (e.g., a stick pusher) is installed, the reference stall speed, VSR, may not be less than 2 knots or 2 percent, whichever is greater, above the speed at which the device operates.
    (amended 2003/11/10; no previous version)
525.105 Take-off
  1. (a) The take-off speeds prescribed by 525.107, the accelerate-stop distance prescribed by 525.109, the take-off path prescribed by 525.111, and the take-off distance and take-off run prescribed by 525.113, and the net take-off flight path prescribed by 525.115 shall be determined in the selected configuration for take-off at each weight, altitude and ambient temperature within the operational limits selected by the applicant:
    (amended 2008/10/30; previous version)
    1. (1) In non-icing conditions; and
      (amended 2008/10/30; previous version)
    2. (2) In icing conditions, if in the configuration of 525.121(b) with the take-off ice accretion defined in Appendix C:
      (amended 2008/10/30; previous version)
      1. (i) The stall speed at maximum take-off weight exceeds that in non-icing conditions by more than the greater of 3 knots CAS or 3 percent of VSR; or
        (amended 2008/10/30; no previous version)
      2. (ii) The degradation of the gradient of climb determined in accordance with 525.121(b) is greater than one-half of the applicable actual-to-net take-off flight path gradient reduction defined in 525.115(b).
        (amended 2008/10/30; no previous version)
  2. (b) No take-off made to determine the data required by this section may require exceptional piloting skill or alertness.
  3. (c) The take-off data must be based on:
    1. (1) In the case of land planes and amphibians:
      1. (i) Smooth, dry and wet, hard-surfaced runways; and
      2. (ii) At the option of the applicant, grooved or porous friction course wet, hard-surfaced runways.
    2. (2) Smooth water, in the case of seaplanes and amphibians; and
    3. (3) Smooth, dry snow, in the case of skiplanes.
  4. (d) The take-off data must include, within the established operational limits of the aeroplane, the following operational correction factors:
    1. (1) Not more than 50 percent of nominal wind components along the take-off path opposite to the direction of take-off, and not less than l50 percent of nominal wind components along the take-off path in the direction of take-off.
    2. (2) Effective runway gradients.

(Change 525-2 (89-01-01))
(Change 525-8)

525.107 Take-off Speeds
  1. (a) V1 must be established in relation to VEF as follows:
    1. (1) VEF is the calibrated air speed at which the critical engine is assumed to fail. VEF must be selected by the applicant, but may not be less than VMCG determined under 525.149(e).
    2. (2) V1, in terms of calibrated airspeed, is selected by the applicant; however, V1 may not be less than VEF plus the speed gained with the critical engine inoperative during the time interval between the instant at which the critical engine is failed, and the instant at which the pilot recognises and reacts to the engine failure, as indicated by the pilot's initiation of the first action (e.g., applying brakes, reducing thrust, deploying speed brakes) to stop the aeroplane during accelerate-stop tests.
  2. (b) V2min, in terms of calibrated airspeed, may not be less than:
    1. (1) 1.13 VSR for:
      (amended 2003/11/10; previous version)
      1. (i) Two-engine and three-engine turbo-propeller and reciprocating engine powered aeroplanes; and
      2. (ii) Turbojet powered aeroplanes without provisions for obtaining a significant reduction in the one-engine-inoperative power-on stall speed;
        (amended 2003/11/10; previous version)
    2. (2) 1.08 VSR for:
      (amended 2003/11/10; previous version)
      1. (i) Turbopropeller and reciprocating engine powered aeroplanes with more than three engines; and
      2. (ii) Turbojet powered aeroplanes with provisions for obtaining a significant reduction in the one-engine-inoperative power-on stall speed ; and
        (amended 2003/11/10; previous version)
    3. (3) 1.10 times VMC established under 525.149.
  3. (c) V2, in terms of calibrated airspeed, shall be selected by the applicant to provide at least the gradient of climb required by 525.121(b) but shall not be less than:
    (amended 2008/10/30; previous version)
    1. (1) V2min;
    2. (2) VR plus the speed increment attained (in accordance with 525.111(c)(2)) before reaching a height of 35 feet above the take-off surface; and
    3. (3) A speed that provides the manoeuvring capability specified in 525.143(h).
      (amended 2008/10/30; previous version)
  4. (d) VMU is the calibrated airspeed at and above which the aeroplane can safely lift off the ground, and continue the take-off. VMU speeds must be selected by the applicant throughout the range of thrust-to-weight ratios to be certificated. These speeds may be established from free air data if these data are verified by ground take-off tests.
  5. (e) VR, in terms of calibrated airspeed, must be selected in accordance with the conditions of subparagraphs (1) through (4) of this paragraph:
    1. (1) VR may not be less than:
      1. (i) V1;
      2. (ii) 105 percent of VMC;
      3. (iii) The speed (determined in accordance with 525.111(c)(2)) that allows reaching V2 before reaching a height of 35 feet above the take-off surface; or
      4. (iv) A speed that, if the aeroplane is rotated at its maximum practicable rate, will result in a VLOF of not less than –
        (effective 2013/02/01)
        1. (A) 110 percent of VMU in the all-engines-operating condition, and 105 percent of VMU determined at the thrust-to-weight ratio corresponding to the one-engine-inoperative condition; or
        2. (B) if the VMU attitude is limited by the geometry of the aeroplane (i.e., tail contact with the runway), 108 percent of VMU in the all-engines-operating condition, and 104 percent of VMU determined at the thrust-to-weight ratio corresponding to the one-engine-inoperative condition.
    2. (2) For any given set of conditions (such as weight, configuration, and temperature), a single value of VR, obtained in accordance with this paragraph, must be used to show compliance with both the one-engine-inoperative and the all-engines-operating take-off provisions.
    3. (3) It must be shown that the one-engine-inoperative take-off distance, using a rotation speed of 5 knots less than VR established in accordance with subparagraphs (1) and (2) of this paragraph, does not exceed the corresponding one-engine-inoperative take-off distance using the established VR. The take-off distances must be determined in accordance with 525.113(a)(1).
    4. (4) Reasonably expected variations in service from the established take-off procedures for the operation of the aeroplane (such as over-rotation of the aeroplane and out-of-trim conditions) may not result in unsafe flight characteristics or in marked increases in the scheduled take-off distances established in accordance with 525.113(a).
  6. (f) VLOF is the calibrated airspeed at which the aeroplane first becomes airborne.
  7. (g) VFTO, in terms of calibrated airspeed, shall be selected by the applicant to provide at least the gradient of climb required by 525.121(c), but shall not be less than
    (amended 2008/10/30; previous version)
    1. (1) 1.18 VSR; and
    2. (2) A speed that provides the manoeurving capability specified in 525.143(h).
      (amended 2008/10/30; previous version)
  8. (h) In determining the take-off speeds V1, VR and V2 for flight in icing conditions, the values of VMCG, VMC and VMU determined for non-icing conditions may be used.
    (amended 2008/10/30; no previous version)

(Change 525-8)

525.109 Accelerate-Stop Distance
  1. (a) The accelerate-stop distance on a dry runway is the greater of the following distances:
    1. (1) The sum of the distances necessary to:
      1. (i) Accelerate the aeroplane from a standing start with all engines operating to VEF for take-off from a dry runway;
      2. (ii) Allow the aeroplane to accelerate from VEF to the highest speed reached during the rejected take-off, assuming the critical engine fails at VEF; and the pilot takes the first action to reject the take-off at the V1 for take-off from a dry runway; and
      3. (iii) Come to a full stop on a dry runway from the speed reached as prescribed in paragraph (a)(1)(ii) of this section; plus
      4. (iv) A distance equivalent to 2 seconds at the V1 for take-off from a dry runway.
    2. (2) The sum of the distances necessary to:
      1. (i) Accelerate the aeroplane from a standing start with all engines operating to the highest speed reached during the rejected take-off, assuming the pilot takes the first action to reject the take-off at the V1 for take-off from a dry runway; and
      2. (ii) With all engines still operating, come to a full stop on dry runway from the speed reached as prescribed in paragraph (a)(2)(i) of this section; plus
      3. (iii) A distance equivalent to 2 seconds at the V1 for take-off from a dry runway.
  2. (b) The accelerate-stop distance on a wet runway is the greater of the following distances:
    1. (1) The accelerate-stop distance on a dry runway determined in accordance with paragraph (a) of this section; or
    2. (2) The accelerate-stop distance determined in accordance with paragraph (a) of this section, except that the runway is wet and the corresponding wet runway values of VEF and V1 are used. In determining the wet runway accelerate-stop distance the stopping force from the wheel brakes may never exceed:
      1. (i) The wheel brakes stopping force determined in meeting the requirements of 525.101(i) and paragraph (a) of this section; and
      2. (ii) The force resulting from the wet runway braking coefficient of friction determined in accordance with paragraphs (c) or (d) of this section, as applicable, taking into account the distribution of the normal load between braked and unbraked wheels at the most adverse centre-of-gravity position approved for take-off.
  3. (c) The wet runway braking coefficient of friction for a smooth wet runway is defined as a curve of friction coefficient versus ground speed and must be computed as follows:
    1. (1) The maximum tire-to-ground wet runway braking coefficient of friction is defined as:

maximum tire-to-ground wet runway braking coefficient of friction chart

Where:

Tire Pressure = maximum aeroplane operating tire pressure (psi);

(m t/gMAX maximum tire-to-ground braking coefficient;

V = aeroplane true ground speed (knots); and

Linear interpolation may be used for tire pressures other than those listed.

  1. (2) The maximum tire-to-ground wet runway braking coefficient of friction must be adjusted to take into account the efficiency of the anti-skid system on a wet runway. Anti-skid system operation must be demonstrated by flight testing on a smooth wet runway, and its efficiency must be determined. Unless a specific anti-skid system efficiency is determined from a quantitative analysis of the flight testing on a smooth wet runway, the maximum tire-to-ground wet runway braking coefficient of friction determined in paragraph (c)(1) of this section must be multiplied by the efficiency value associated with the type of anti-skid system installed on the aeroplane:
Type of anti-skid system Efficiency value
On-Off

Quasi-Modulating

Fully Modulating
0.30

0.50

0.80
  1. (d) At the option of the applicant, a higher wet runway braking coefficient of friction may be used for runway surfaces that have been grooved or treated with a porous friction course material. For grooved and porous friction course runways, the wet runway braking coefficient of friction is defined as either:
    1. (1) 70 percent of the dry runway braking coefficient of friction used to determine the dry runway accelerate-stop distance; or
    2. (2) The wet runway braking coefficient defined in paragraph (c) of this section, except that a specific anti-skid system efficiency, if determined, is appropriate for a grooved or porous friction course wet runway, and the maximum tire-to-ground wet runway braking coefficient of friction is defined as:

maximum tire-to-ground wet runway braking coefficient of friction chart 

Where:

Tire Pressure = maximum aeroplane operating tire pressure (psi);

(mt/gMAX maximum tire-to-ground braking coefficient;

V = aeroplane true ground speed (knots); and

Linear interpolation may be used for tire pressures other than those listed.

  1. (e) Except as provided in paragraph (f)(1) of this section, means other than wheel brakes may be used to determine the accelerate-stop distance if that means:
    1. (1) Is safe and reliable;
    2. (2) Is used so that consistent results can be expected under normal operating conditions; and
    3. (3) Is such that exceptional skill is not required to control the aeroplane.
  2. (f) The effects of available reverse thrust:
    1. (1) Shall not be included as an additional means of deceleration when determining the accelerate-stop distance on a dry runway; and
    2. (2) May be included as an additional means of deceleration using recommended reverse thrust procedures when determining the accelerate-stop distance on a wet runway, provided the requirements of paragraph (e) of this section are met.
  3. (g) The landing gear must remain extended throughout the accelerate-stop distance.
  4. (h) If the accelerate-stop distance includes a stopway with surface characteristics substantially different from those of the runway, the take-off data must include operational correction factors for the accelerate-stop distance. The correction factors must account for the particular surface characteristics of the stopway and the variations in these characteristics with seasonal weather conditions (such as temperature, rain, snow, and ice) within the established operational limits.
  5. (i) A flight test demonstration of the maximum brake kinetic energy accelerate-stop distance must be conducted with not more than 10 percent of the allowable brake wear range remaining on each of the aeroplane wheel brakes.

(Change 525-8)

525.111 Take-off Path

  1. (a) The take-off path extends from a standing start to a point in the take-off at which the aeroplane is 1,500 feet above the take-off surface, or at which the transition from the take-off to the en route configuration is completed and VFTO is reached, whichever point is higher. In addition:
    (amended 2003/11/10; previous version)
    1. (1) The take-off path shall be based on the procedures prescribed in 525.101(f);
      (amended 2003/11/10; previous version)
    2. (2) The aeroplane shall be accelerated on the ground to VEF, at which point the critical engine shall be made inoperative and remain inoperative for the rest of the take-off; and
      (amended 2003/11/10; previous version)
    3. (3) After reaching VEF, the aeroplane shall be accelerated to V2.
      (amended 2003/11/10; previous version)
  2. (b) During the acceleration to speed V2, the nose gear may be raised off the ground at a speed not less than VR. However, landing gear retraction shall not begin until the aeroplane is airborne.
    (amended 2005/06/03; previous version)
  3. (c) During the take-off path determination in accordance with paragraphs (a) and (b) of this section:
    1. (1) The slope of the airborne part of the take-off path shall be positive at each point;
      (amended 2005/06/03; previous version)
    2. (2) The aeroplane shall reach V2 before it is 35 feet above the take-off surface and shall continue at a speed as close as practical to, but not less than V2, until it is 400 feet above the take-off surface;
      (amended 2005/06/03; previous version)
    3. (3) At each point along the take-off path, starting at the point at which the aeroplane reaches 400 feet above the take-off surface, the available gradient of climb shall not be less than:
      (amended 2005/06/03; previous version)
      1. (i) 1.2 percent for two-engine aeroplanes;
      2. (ii) 1.5 percent for three-engine aeroplanes; and
      3. (iii) 1.7 percent for four-engine aeroplanes; and
    4. (4) The aeroplane configuration shall not be changed, except for landing gear retraction and automatic propeller feathering, and no change in power or thrust that requires action by the pilot shall be made, until the aeroplane is 400 feet above the take-off surface; and
      (amended 2008/10/30; previous version)
    5. (5) If 525.105(a)(2) requires the take-off path to be determined for flight in icing conditions, the airborne part of the take-off shall be based on the aeroplane drag:
      (amended 2008/10/30; no previous version)
      1. (i) With the take-off ice accretion defined in Appendix C, from a height of 35 feet above the take-off surface up to the point where the aeroplane is 400 feet above the take-off surface; and
        (amended 2008/10/30; no previous version)
      2. (ii) With the final take-off ice accretion defined in Appendix C, from the point where the aeroplane is 400 feet above the take-off surface to the end of the take-off path.
        (amended 2008/10/30; no previous version)
  4. (d) The take-off path shall be determined by a continuous demonstrated take-off or by synthesis from segments. If the take-off path is determined by the segmental method:
    (amended 2005/06/03; previous version)
    1. (1) The segments shall be clearly defined and shall be related to the distinct changes in the configuration, power or thrust, and speed;
      (amended 2005/06/03; previous version)
    2. (2) The weight of the aeroplane, the configuration, and the power or thrust shall be constant throughout each segment and shall correspond to the most critical condition prevailing in the segment;
      (amended 2005/06/03; previous version)
    3. (3) The flight path shall be based on the aeroplane's performance without ground effect; and
      (amended 2005/06/03; previous version)
    4. (4) The take-off path data shall be checked by continuous demonstrated take-offs up to the point at which the aeroplane is out of ground effect and its speed is stabilised, to ensure that the path is conservative relative to the continuous path. The aeroplane is considered to be out of the ground effect when it reaches a height equal to its wing span.
      (amended 2005/06/03; previous version)
  5. (e) For aeroplanes equipped with standby power rocket engines, the take-off path may be determined in accordance with Part II of Appendix E.

(Change 525-3 (91-11-01))

525.113 Take-off Distance and Take-off Run
  1. (a) Take-off distance on a dry runway is the greater of:
    1. (1) The horizontal distance along the take-off path from the start of the take-off to the point at which the aeroplane is 35 feet above the take-off surface, determined under 525.111; for a dry runway; or
    2. (2) 115 percent of the horizontal distance along the take-off path, with all engines operating, from the start of the take-off to the point at which the aeroplane is 35 feet above the take-off surface, as determined by a procedure consistent with 525.111.
  2. (b) Take-off distance on a wet runway is the greater of:
    1. (1) The take-off distance on a dry runway determined in accordance with paragraph (a) of this section; or
    2. (2) The horizontal distance along the take-off path from the start of the take-off to the point at which the aeroplane is 15 feet above the take-off surface, achieved in a manner consistent with the achievement of V2 before reaching 35 feet above the take-off surface, determined under 525.111 for a wet runway.
  3. (c) If the take-off distance does not include a clearway, the take-off run is equal to the take-off distance. If the take-off distance includes a clearway:
    1. (1) The take-off run on a dry runway is the greater of:
      1. (i) The horizontal distance along the take-off path from the start of the take-off to a point equidistant between the point at which VLOF is reached and the point at which the aeroplane is 35 feet above the take-off surface, as determined under 525.111; for a dry runway; or
      2. (ii) 115 percent of the horizontal distance along the take-off path, with all engines operating, from the start of the take-off to a point equidistant between the point at which VLOF is reached and the point at which the aeroplane is 35 feet above the take-off surface, determined by a procedure consistent with 525.111.
    2. (2) The take-off run on a wet runway is the greater of:
      1. (i) The horizontal distance along the take-off path form the start of the take-off to the point at which the aeroplane is 15 feet above the take-off surface, achieved in a manner consistent with the achievement of V2 before reaching 35 feet above the take-off surface, as determined under 525.111 for a wet runway; or
      2. (ii) 115 percent of the horizontal distance along the take-off flight path, with all engines operating, from the start of the take-off to a point equidistant between the point at which VLOF is reached and the point at which the aeroplane is 35 feet above the take-off surface, determined by a procedure consistent with 525.111.

(Change 525-8)

525.115 Take-off Flight Path
  1. (a) The take-off flight path shall be considered to begin 35 feet above the take-off surface at the end of the take-off distance determined in accordance with 525.113(a) or (b), as appropriate for the runway surface condition.
  2. (b) The net take-off flight path data must be determined so that they represent the actual take-off flight paths (determined in accordance with 525.111 and with paragraph (a) of this section) reduced at each point by a gradient of climb equal to:
    1. (1) 0.8 percent for two-engine aeroplanes;
    2. (2) 0.9 percent for three-engine aeroplanes; and
    3. (3) 1.0 percent for four-engine aeroplanes.
  3. (c) The prescribed reduction in climb gradient may be applied as an equivalent reduction in acceleration along that part of the take-off flight path at which the aeroplane is accelerated in level flight.

(Change 525-8)

525.117 Climb:
General

Compliance with the requirements of 525.119 and 525.121 must be shown at each weight, altitude, and ambient temperature within the operational limits established for the aeroplane and with the most unfavourable centre of gravity for each configuration.

525.119 Landing Climb:
All-Engines-Operating

In the landing configuration, the steady gradient of climb shall not be less than 3.2 percent, with the engines at the power or thrust that is available eight seconds after initiation of movement of the power or thrust controls from the minimum flight idle to the go-around power or thrust setting:
(amended 2008/10/30; previous version)

  1. (a) In non-icing conditions, with a climb speed of VREF determined in accordance with 525.125(b)(2)(i); and
    (amended 2008/10/30; previous version)
  2. (b) In icing conditions with the landing ice accretion defined in Appendix C, and with a climb speed of VREF determined in accordance with 525.125(b)(2)(ii).
    (amended 2008/10/30; previous version)

(Change 525-7 (96-09-30))

525.121 Climb:
One-Engine-Inoperative
  1. (a) Take-off; landing gear extended. In the critical take-off configuration existing along the flight path (between the points at which the aeroplane reaches VLOF and at which the landing gear is fully retracted) and in the configuration used in 525.111 but without ground effect, the steady gradient of climb must be positive for two-engine aeroplanes, and not less than 0.3 percent for three-engine aeroplanes or 0.5 percent for four-engine aeroplanes, at VLOF and with:
    1. (1) The critical engine inoperative and the remaining engines at the power or thrust available when retraction of the landing gear is begun in accordance with 525.111 unless there is a more critical power operating condition existing later along the flight path but before the point at which the landing gear is fully retracted; and
    2. (2) The weight equal to the weight existing when retraction of the landing gear is begun, determined under 525.111.
  2. (b) Take-off; landing gear retracted. In the take-off configuration existing at the point of the flight path at which the landing gear is fully retracted, and in the configuration used in 525.111 but without ground effect:
    (amended 2008/10/30; previous version)
    1. (1) The steady gradient of climb shall not be less than 2.4 percent for two-engine aeroplanes, 2.7 percent for three-engine aeroplanes, and 3.0 percent for four-engine aeroplanes, at V2 with:
      (amended 2008/10/30; previous version)
      1. (i) The critical engine inoperative, the remaining engines at the take-off power or thrust available at the time the landing gear is fully retracted, as determined under 525.111, unless there is a more critical power operating condition existing later along the flight path but before the point where the aeroplane reaches a height of 400 feet above the take-off surface; and
        (amended 2008/10/30; previous version)
      2. (ii) The weight equal to the weight existing when the aeroplane's landing gear is fully retracted, as determined under 525.111.
        (amended 2008/10/30; previous version)
    2. (2) The requirements of paragraph (b)(1) of this section shall be met:
      (amended 2008/10/30; previous version)
      1. (i) In non-icing conditions; and
        (amended 2008/10/30; previous version)
      2. (ii) In icing conditions with the take-off ice accretion defined in Appendix C, if in the configuration of 525.121(b) with the take-off ice accretion:
        (amended 2008/10/30; previous version)
        1. (A) The stall speed at maximum take-off weight exceeds that in non-icing conditions by more than the greater of 3 knots CAS or 3 percent of VSR; or
          (amended 2008/10/30; previous version)
        2. (B) The degradation of the gradient of climb determined in accordance with 525.121(b) is greater than one-half of the applicable actual-to-net take-off flight path gradient reduction defined in 525.115(b).
          (amended 2008/10/30; previous version)
  3. (c) Final take-off. In the en route configuration at the end of the take-off path determined in accordance with 525.111:
    (amended 2008/10/30; previous version)
    1. (1) The steady gradient of climb shall not be less than 1.2 percent for two-engine aeroplanes, 1.5 percent for three-engine aeroplanes, and 1.7 percent for four-engine aeroplanes, at VFTO with:
      (amended 2008/10/30; previous version)
      1. (i) The critical engine inoperative and the remaining engines at the available maximum continuous power or thrust; and
        (amended 2008/10/30; previous version)
      2. (ii) The weight equal to the weight existing at the end of the take-off path, determined under 525.111.
        (amended 2008/10/30; previous version)
    2. (2) The requirements of paragraph (c)(1) of this section shall be met:
      (amended 2008/10/30; previous version)
      1. (i) In non-icing conditions; and
        (amended 2008/10/30; previous version)
      2. (ii) In icing conditions with the final take-off ice accretion defined in Appendix C, if in the configuration of 525.121(b) with the take-off ice accretion:
        (amended 2008/10/30; previous version)
        1. (A) The stall speed at maximum take-off weight exceeds that in non-icing conditions by more than the greater of 3 knots CAS or 3 percent of VSR; or
          (amended 2008/10/30; previous version)
        2. (B) The degradation of the gradient of climb determined in accordance with 525.121(b) is greater than one-half of the applicable actual-to-net take-off flight path gradient reduction defined in 525.115(b).
          (amended 2008/10/30; previous version)
  4. (d) Approach. In a configuration corresponding to the normal all-engines-operating procedure in which VSR for this configuration does not exceed 110 percent of the VSR for the related all-engines-operating landing configuration:
    (amended 2008/10/30; previous version)
    1. (1) The steady gradient of climb shall not be less than 2.1 percent for two-engine aeroplanes, 2.4 percent for three-engine aeroplanes, and 2.7 percent for four-engine aeroplanes, with:
      (amended 2008/10/30; previous version)
      1. (i) The critical engine inoperative, the remaining engines at the go-around power or thrust setting;
        (amended 2008/10/30; previous version)
      2. (ii) The maximum landing weight;
        (amended 2008/10/30; previous version)
      3. (iii) The climb speed established in connection with normal landing procedures, but not exceeding 1.4 VSR; and
        (amended 2008/10/30; previous version)
      4. (iv) Landing gear retracted.
        (amended 2008/10/30; previous version)
    2. (2) The requirements of paragraph (d)(1) of this section shall be met:
      (amended 2008/10/30; previous version)
      1. (i) In non-icing conditions; and
        (amended 2008/10/30; previous version)
      2. (ii) In icing conditions with the approach ice accretion defined in Appendix C. The climb speed selected for non-icing conditions may be used if the climb speed for icing conditions, computed in accordance with (d)(1)(iii) of this section, does not exceed that for non-icing conditions by more than the greater of 3 knots CAS or 3 percent.
        (amended 2008/10/30; previous version)
    3. (3) A climb speed established in connection with normal landing procedures, but not more than 1.4 VSR; and
      (amended 2003/11/10; previous version)
    4. (4) Landing gear retracted.
      (amended 2003/11/10; no previous version)

(Change 525-7 (96-09-30))

525.123 En Route Flight Paths
  1. (a) For the en route configuration, the flight paths prescribed in paragraphs (b) and (c) of this section shall be determined at each weight, altitude, and ambient temperature, within the operating limits established for the aeroplane. The variation of weight along the flight path, accounting for the progressive consumption of fuel and oil by the operating engines, may be included in the computation. The flight paths shall be determined at a speed not less than VFTO, with:
    (amended 2008/10/30; previous version)
    1. (1) The most unfavourable centre of gravity;
    2. (2) The critical engines inoperative;
    3. (3) The remaining engines at the available maximum continuous power or thrust; and
    4. (4) The means for controlling the engine-cooling air supply in the position that provides adequate cooling in the hot-day condition.
  2. (b) The one-engine-inoperative net flight path data shall represent the actual climb performance diminished by a gradient of climb of 1.1 percent for two-engine aeroplanes, 1.4 percent for three-engine aeroplanes, and 1.6 percent for four-engine aeroplanes:
    (amended 2008/10/30; previous version)
    1. (1) In non-icing conditions; and
      (amended 2008/10/30; no previous version)
    2. (2) In icing conditions with the en route ice accretion as defined in Appendix C, if:
      (amended 2008/10/30; no previous version)
      1. (i) A speed of 1.18 VSR with the en route ice accretion exceeds the en route speed selected for non-icing conditions by more than the greater of 3 knots CAS or 3 percent of VSR; or
        (amended 2008/10/30; no previous version)
      2. (ii) The degradation of the gradient of climb is greater than one-half of the applicable actual-to-net flight path reduction defined in (b) of this section.
        (amended 2008/10/30; no previous version)
  3. (c) For three or four-engine aeroplanes, the two-engine-inoperative net flight path data must represent the actual climb performance diminished by a gradient climb of 0.3 percent for three-engine aeroplanes and 0.5 percent for four-engine aeroplanes.
525.125 Landing
  1. (a) The horizontal distance necessary to land and to come to a complete stop (or to a speed of approximately 3 knots for water landings) from a point 50 feet above the landing surface shall be determined (for standard temperatures, at each weight, altitude and wind within the operational limits established by the applicant for the aeroplane):
    (amended 2008/10/30; previous version)
    1. (1) In non-icing conditions; and
      (amended 2008/10/30; previous version)
    2. (2) In In icing conditions with the landing ice accretion defined in Appendix C if VREF for icing conditions exceeds VREF for non-icing conditions by more than 5 knots CAS at the maximum landing weight.
      (amended 2008/10/30; previous version)
  2. (b) In determining the distance in subsection (a) of this section:
    (amended 2008/10/30; previous version)
    1. (1) The aeroplane shall be in the landing configuration.
      (amended 2008/10/30; previous version)
    2. (2) A stabilized approach, with a calibrated airspeed of not less than VREF shall be maintained down to the 50 foot height.
      (amended 2008/10/30; previous version)
      1. (i) In non-icing conditions, VREF shall not be less than:
        (amended 2008/10/30; previous version)
        1. (A) 1.23 VSR0;
        2. (B) VMCL established under 525.149(f); and
        3. (C) A speed that provides the manoeuvring capability specified in 525.143(h).
      2. (ii) In icing conditions, VREF shall not be less than:
        (amended 2008/10/30; previous version)
        1. (A) The speed determined in paragraph (b)(2)(i) of this section;
        2. (B) 1.23 VSR0 with the landing ice accretion defined in Appendix C if that speed exceeds VREF for non-icing conditions by more than 5 knots CAS; and
        3. (C) A speed that provides the manoeuvering capability specified in 525.143(h) with the landing ice accretion defined in Appendix C.
    3. (3) Changes in configuration, power or thrust, and speed, shall be made in accordance with the established procedures for service operation.
      (amended 2008/10/30; previous version)
    4. (4) The landing shall be made without excessive vertical acceleration, tendency to bounce, nose over, ground loop, porpoise, or water loop.
      (amended 2008/10/30; previous version)
    5. (5) The landing shall not require exceptional piloting skill or alertness.
      (amended 2008/10/30; previous version)
  3. (c) For landplanes and amphibians, the landing distance on land shall be determined on a level, smooth, dry, hard-surfaced runway. In addition:
    (amended 2008/10/30; previous version)
    1. (1) The pressures on the wheel braking systems shall not exceed those specified by the brake manufacturer;
    2. (2) The brakes shall not be used so as to cause excessive wear of brakes or tires; and
    3. (3) Means other than wheel brakes shall be used if that means:
      1. (i) Is safe and reliable;
      2. (ii) Is used so that consistent results can be expected in service; and
      3. (iii) Is such that exceptional skill is not required to control the aeroplane.
  4. (d) For seaplanes and amphibians, the landing distance on water shall be determined on smooth water.
    (amended 2008/10/30; previous version)
  5. (e) The skiplanes, the landing distance on snow shall be determined on smooth, dry snow.
    (amended 2008/10/30; previous version)
  6. (f) The landing distance data shall include correction factors for not more than 50 percent of the nominal wind components along the landing path opposite to the direction of landing, and not less than 150 percent of the nominal wind components along the landing path in the direction of landing.
    (amended 2008/10/30; previous version)
  7. (g) If any device is used that depends on the operation of any engine, and if the landing distance would be noticeably increased when landing is made with that engine inoperative, the landing distance shall be determined with that engine inoperative unless the use of compensating means will result in a landing distance not more than that with each engine operating.
    (amended 2008/10/30; previous version)

(Change 525-2 (89-01-01))
(Change 525-3 (91-11-01))
(Change 525-7 (96-09-30))
(Change 525-8)

Controllability and Manoeuvrability
525.143 General
  1. (a) The aeroplane must be safely controllable and manoeuvrable during:
    1. (1) Take-off;
    2. (2) Climb;
    3. (3) Level flight;
    4. (4) Descent; and
    5. (5) Landing.
  2. (b) It must be possible to make a smooth transition from one flight condition to any other flight condition without exceptional piloting skill, alertness, or strength, and without danger of exceeding the aeroplane limit-load factor under an probable operating conditions, including:
    1. (1) The sudden failure of the critical engine;
    2. (2) For aeroplanes with three or more engines, the sudden failure of the second critical engine when the aeroplane is in the en route, approach, or landing configuration and is trimmed with the critical engine inoperative; and
    3. (3) Configuration changes, including deployment or retraction of deceleration devices.
  3. (c) The aeroplane shall be shown to be safely controllable and manoeuvrable with the critical ice accretion appropriate to the phase of flight defined in Appendix C, and with the critical engine inoperative and its propeller (if applicable) in the minimum drag position:
    (amended 2008/10/30; previous version)
    1. (1) At the minimum V2 for take-off;
      (amended 2008/10/30; previous version)
    2. (2) During an approach and go-around; and
      (amended 2008/10/30; previous version)
    3. (3) During an approach and landing.
      (amended 2008/10/30; previous version)
  4. (d) The following table prescribes, for conventional wheel type controls, the maximum control forces permitted during the testing required by paragraphs (a) through (c) of this section:
    (amended 2008/10/30; previous version)
Force, In Pounds, Applied To The Control Wheel Or Rudder Pedals Pitch Roll Yaw
For short term application for pitch and roll control - two hands available for control 75 50 ---
For short term application for pitch and roll control - one hand available for control 50 25 ---
For short term application for yaw control --- --- 150
For long term application 10 5 20
(amended 2008/10/30; previous version)

(e) Approved operating procedures or conventional operating practices shall be followed when demonstrating compliance with the control force limitations for short term application that are prescribed in paragraph (d) of this section. The aeroplane shall be in trim, or as near to being in trim as practical, in the preceding steady flight condition. For the take-off condition, the aeroplane shall be trimmed according to the approved operating procedures.
(amended 2008/10/30; previous version)

(f) When demonstrating compliance with the control force limitations for long term application that are prescribed in paragraph (d) of this section, the aeroplane shall be in trim, or as near to being in trim as practical.
(amended 2008/10/30; previous version)

(g) When manoeuvring at a constant airspeed or Mach number (up to VFC/MFC), the stick forces and the gradient of the stick force versus manoeuvring load factor shall lie within satisfactory limits. The stick forces shall not be so great as to make excessive demands on the pilot's strength when manoeuvring the aeroplane, and shall not be so low that the aeroplane can easily be overstressed inadvertently. Changes of gradient that occur with changes of load factor shall not cause undue difficulty in maintaining control of the aeroplane, and local gradients must not be so low as to result in a danger of overcontrolling.
(amended 2008/10/30; previous version)

(h) The manoeuvring capabilities in a constant speed coordinated turn at forward centre of gravity, as specified in the following table, shall be free of stall warning or other characteristics that might interfere with normal manoeuvring:
(amended 2008/10/30; previous version)

Configuration Speed Manoeuvring bank
angle in a
coordinated turn
Thrust power setting
Take-off V2 30° Asymmetric WAT-Limited.1
Take-off 2V2 +XX 40° All-engines-operating climb.3
En route VFTO 40° Asymmetric WAT-Limited.1
Landing VREF 40° Symmetric for -3° flight path angle.
1 A combination of weight, altitude, and temperature (WAT) such that the thrust or power setting produces the minimum climb gradient specified in 525.121 for the flight condition.

2 Airspeed approved for all-engines-operating initial climb.

3 That thrust or power setting which, in the event of failure of the critical engine and without any flight crew action to adjust the thrust or power of the remaining engines, would result in the thrust or power specified for the take-off condition at V2, or any lesser thrust or power setting that is used for all-engines-operating initial climb procedures.
(amended 2008/10/30; previous version)
  1. (i) When demonstrating compliance with 525.143 in icing conditions:
    (amended 2008/10/30; no previous version)
    1. (1) Controllability shall be demonstrated with the ice accretion defined in Appendix C that is most critical for the particular flight phase;
      (amended 2008/10/30; no previous version)
    2. (2) It shall be shown that a push force is required throughout a pushover manoeuver down to a zero g load factor, or the lowest load factor obtainable if limited by elevator power or other design characteristic of the flight control system. It shall be possible to promptly recover from the manoeuvre without exceeding a pull control force of 50 pounds; and
      (amended 2008/10/30; no previous version)
    3. (3) Any changes in force that the pilot shall apply to the pitch control to maintain speed with increasing sideslip angle shall be steadily increasing with no force reversals, unless the change in control force is gradual and easily controllable by the pilot without using exceptional piloting skill, alertness, or strength.
      (amended 2008/10/30; no previous version)
  2. (j) For flight in icing conditions before the ice protection system has been activated and is performing its intended function, it must be demonstrated in flight with the ice accretion defined in Appendix C, Part II(e) of this Chapter that:
    (effective 2014/11/30)
    1. (1) the aeroplane is controllable in a pull-up manoeuvre up to 1.5 g load factor; and
      (effective 2014/11/30)
    2. (2) there is no pitch control force reversal during a pushover manoeuvre down to 0.5 g load factor.
      (effective 2014/11/30)

(Change 525-2 (89-01-01))
(Change 525-7 (96-09-30))

525.145 Longitudinal Control
  1. (a) It shall be possible, at any point between the trim speed prescribed in 525.103(b)(6) and stall identification (as defined in 525.201(d)), to pitch the nose downward so that the acceleration to this selected trim speed is prompt with:
    (amended 2003/11/10; previous version)
    1. (1) The aeroplane trimmed at the trim speed prescribed in 525.103 (b)(6);
      (amended 2003/11/10; previous version)
    2. (2) The landing gear extended;
    3. (3) The wing flaps (i) retracted and (ii) extended; and
    4. (4) Power (i) off and (ii) at maximum continuous power on the engines.
  2. (b) With the landing gear extended, no change in trim control, or exertion of more than 50 pounds control force (representative of the maximum short term force that can be applied readily by one hand) may be required for the following manoeuvres:
    1. (1) With power off, flaps retracted, and the aeroplane trimmed at 1.3 VSR1, extend the flaps as rapidly as possible while maintaining the airspeed at approximately 30 percent above the reference stall speed existing at each instant throughout the manoeuvre.
      (amended 2003/11/10; previous version)
    2. (2) Repeat paragraph (b)(1) except initially extend the flaps and then retract them as rapidly as possible.
      (amended 2003/11/10; previous version)
    3. (3) Repeat paragraph (b)(2), except at the go-around power or thrust setting.
    4. (4) With power off, flaps retracted, and the aeroplane trimmed at 1.3 VSR1, rapidly set go-around power or thrust while maintaining the same airspeed.
      (amended 2003/11/10; previous version)
    5. (5) Repeat paragraph (b)(4) except with flaps extended.
      (amended 2003/11/10; previous version)
    6. (6) With power off, flaps extended, and the aeroplane trimmed at 1.3 VSR1, obtain and maintain airspeeds between VSW and either 1.6 VSR1, or VFE, whichever is lower.
      (amended 2003/11/10; previous version)
  3. (c) It shall be possible, without exceptional piloting skill, to prevent loss of altitude when complete retraction of the high-lift devices from any position is begun during steady, straight, level flight at 1.08 VSR1 for propeller powered aeroplanes, or 1.13 VSR1 for turbojet powered aeroplanes, with:
    (amended 2003/11/10; previous version)
    1. (1) Simultaneous movement of the power or thrust controls to the go-around power or thrust setting;
    2. (2) The landing gear extended; and
    3. (3) The critical combinations of landing weights and altitudes.
  4. (d) If gated high-lift device control positions are provided, paragraph (c) of this section applies to retractions of the high-lift devices from any position from the maximum landing position to the first gated position, between gated positions, and from the last gated position to the fully retracted position. The requirements of paragraph (c) of this section also apply to retractions from each approved landing position to the control position(s) associated with the high-lift device configuration(s) used to establish the go-around procedure(s) from that landing position. In addition, the first gated control position from the maximum landing position must correspond with a configuration of the high-lift devices used to establish a go-around procedure from a landing configuration. Each gated control position must require a separate and distinct motion of the control to pass through the gated position and must have features to prevent inadvertent movement of the control through the gated position. It must only be possible to make this separate and distinct motion once the control has reached the gated position.

(Change 525-2 (89-01-01))
(Change 525-3 (91-11-01))
(Change 525-7 (96-09-30))
(Change 525-8)

525.147 Directional and Lateral Control
  1. (a) Directional Control, General. It shall be possible, with the wings level, to yaw into the operative engine and to safely make a reasonably sudden change in heading of up to 15 degrees in the direction of the critical inoperative engine. This shall be demonstrated at 1.3 VSR1 for heading changes up to 15° (except that the heading change at which the rudder pedal force is 150 pounds need not be exceeded), and with:
    (amended 2003/11/10; previous version)
    1. (1) The critical engine inoperative and its propeller in the minimum drag position;
    2. (2) The power required for level flight at 1.3 VSR1, but not more than maximum continuous power;
      (amended 2003/11/10; previous version)
    3. (3) The most unfavourable centre of gravity;
    4. (4) Landing gear retracted;
    5. (5) Flaps in the approach position; and
    6. (6) Maximum landing weight.
  2. (b) Directional control; aeroplanes with four or more engines. Aeroplanes with four or more engines shall meet the requirements of paragraph (a) of this section except that:
    (amended 2003/11/10; previous version)
    1. (1) The two critical engines shall be inoperative with their propellers (if applicable) in the minimum drag position;
      (amended 2003/11/10; previous version)
    2. (2) (Reserved);
    3. (3) The flaps shall be in the most favourable climb position.
      (amended 2003/11/10; previous version)
  3. (c) Lateral control; general It shall be possible to make 20° banked turns, with and against the inoperative engine, from steady flight at a speed equal to 1.3 VSR1 with:
    (amended 2003/11/10; previous version)
    1. (1) The critical engine inoperative and its propeller (if applicable) in the minimum drag position;
    2. (2) The remaining engines at maximum continuous power;
    3. (3) The most unfavourable centre of gravity;
    4. (4) Landing gear (i) retracted and (ii) extended;
    5. (5) Flaps in the most favourable climb position; and
    6. (6) Maximum take-off weight.
  4. (d) Lateral control; roll capability. With the critical engine inoperative, roll response shall allow normal manoeuvres. Lateral control shall be sufficient, at the speeds likely to be used with one engine inoperative, to provide a roll rate necessary for safety without excessive control forces or travel.
    (amended 2005/06/03; previous version)
  5. (e) Lateral control; aeroplanes with four or more engines. Aeroplanes with four or more engines shall be able to make 20° banked turns, with and against the inoperative engines, from steady flight at a speed equal to 1.3 VSR1, with maximum continuous power, and with the aeroplane in the configuration prescribed by paragraph (b) of this section.
    (amended 2003/11/10; previous version)
  6. (f) Lateral control; all engines operating. With the engines operating, roll response shall allow normal manoeuvres (such as recovery from upsets produced by gusts and the initiation of evasive manoeuvres). There shall be enough excess lateral control in sideslips (up to sideslip angles that might be required in normal operation), to allow a limited amount of manoeuvring and to correct for gusts. Lateral control shall be enough at any speed up to VFC/MFC to provide a peak roll rate necessary for safety, without excess control forces or travel.
    (amended 2003/11/10; previous version)

(Change 525-3 (91-11-01))

525.149 Minimum Control Speed
  1. (a) In establishing the minimum control speeds required by this section, the method used to simulate critical engine failure must represent the most critical mode of powerplant failure with respect to controllability expected in service.
  2. (b) VMC is the calibrated air-speed, at which, when the critical engine is suddenly made inoperative, it is possible to maintain control of the aeroplane with that engine still inoperative and maintain straight flight with an angle or bank of not more than 5 degrees.
  3. (c) VMC may not exceed 1.13 VSR with:
    (amended 2003/11/10; previous version)
    1. (1) Maximum available take-off power or thrust on the engines;
    2. (2) The most unfavourable centre of gravity;
    3. (3) The aeroplane trimmed for take-off;
    4. (4) The maximum sea level take-off weight (or any lesser weight necessary to show VMC);
    5. (5) The aeroplane in the most critical take-off configuration existing along the flight path after the aeroplane becomes airborne, except with the landing gear retracted; and
    6. (6) The aeroplane airborne and the ground effect negligible; and
    7. (7) If applicable, the propeller of the inoperative engine:
      1. (i) Windmilling;
      2. (ii) In the most probable position for the specific design of the specific design of the propeller control; or
      3. (iii) Feathered, if the aeroplane has an automatic feathering device acceptable for showing compliance with the climb requirements of 525.121.
  4. (d) The rudder forces required to maintain control at VMC may not exceed 150 pounds nor may it be necessary to reduce power or thrust of the operative engines. During recovery, the aeroplane may not assume any dangerous attitude or require exceptional piloting skill, alertness, or strength to prevent a heading change of more than 20 degrees.
  5. (e) VMCG, the minimum control speed on the ground, is the calibrated airspeed during the take-off run at which, when the critical engine is suddenly made inoperative, it is possible to maintain control of the aeroplane using rudder control alone (without the use of nose-wheel steering), as limited by 150 pounds of force, and the lateral control to the extent of keeping the wings level to enable the take-off to be safely continued using normal piloting skill. In the determination of VMCG, assuming that the path of the aeroplane accelerating with all engines operating is along the centreline of the runway, its path from the point at which the critical engine is made inoperative to the point at which recovery to a direction parallel to the centreline is completed may not deviate more than 30 feet laterally from the centreline at any point. VMCG must be established with:
    1. (1) The aeroplane in each take-off configuration or, at the option of the applicant, in the most critical take-off configuration;
    2. (2) Maximum available take-off power or thrust on the operating engines;
    3. (3) The most unfavourable centre of gravity;
    4. (4) The aeroplane trimmed for take-off; and
    5. (5) The most unfavourable weight in the range of take-off weights.
  6. (f) VMCL, the minimum control speed during approach and landing with all engines operating, is the calibrated airspeed at which, when the critical engine is suddenly made inoperative, it is possible to maintain control of the aeroplane with that engine still inoperative, and maintain straight flight with an angle of bank of not more than 5 degrees. VMCLL must be established with:
    1. (1) The aeroplane in the most critical configuration (or, at the option of the applicant, each configuration) for approach and landing with all engines operating;
    2. (2) The most unfavourable centre of gravity;
    3. (3) The aeroplane trimmed for approach with all engines operating;
    4. (4) The most favourable weight, or, at the option of the applicant, as a function of weight;
    5. (5) For propeller aeroplanes, the propeller of the inoperative engine in the position it achieves without pilot action, assuming the engine fails while at the power or thrust necessary to maintain a three degree approach path angle; and
    6. (6) Go-around power or thrust setting on the operating engine(s).
  7. (g) For aeroplanes with three or more engines VMCL-2 the minimum control speed during approach and landing with one critical engine inoperative, is the calibrated airspeed at which, when a second critical engine is suddenly made inoperative, it is possible to maintain control of the aeroplane with both engines still inoperative and maintain straight flight with an angle of bank of not more than 5 degrees. VMCL-2 must be established with:
    1. (1) The aeroplane in the most critical configuration (or, at the option of the applicant, each configuration) for approach and landing with one critical engine inoperative;
    2. (2) The most unfavourable centre of gravity;
    3. (3) The aeroplane trimmed for approach with one critical engine inoperative;
    4. (4) The most unfavourable weight, or, at the option of the applicant, as a function of weight;
    5. (5) For propeller aeroplanes, the propeller of the more critical inoperative engine in the position it achieves without pilot action, assuming the engine fails while at the power or thrust necessary to maintain a three degree approach path angle, and the propeller of the other inoperative engine feathered;
    6. (6) The power or thrust on the operating engine(s) necessary to maintain an approach path angle of three degrees when one critical engine is inoperative; and
    7. (7) The power or thrust on the operating engine(s) rapidly changed, immediately after the second critical engine is made inoperative, from the power or thrust prescribed in paragraph (g) (6) of this section to:
      1. (i) Minimum power or thrust; and
      2. (ii) Go-around power or thrust setting.
  8. (h) In demonstration of VMCL and VMCL-2:
    1. (1) The rudder force may not exceed 150 pounds;
    2. (2) The aeroplane may not exhibit hazardous flight characteristics or require exceptional piloting skill, alertness, or strength;
    3. (3) Lateral control must be sufficient to roll the aeroplane, from an initial condition of steady flight, through an angle of 20 degrees in the direction necessary to initiate a turn away from the inoperative engine(s), in not more than 5 seconds; and
    4. (4) For propeller aeroplanes, hazardous flight characteristics must not be exhibited due to any propeller position achieved when the engine fails or during any likely subsequent movements of the engine or propeller controls.

(Change 525-3 (91-11-01))
(Change 525-7 (96-09-30))

Trim
525.161 Trim
  1. (a) General. Each aeroplane shall meet the trim requirements of this section after being trimmed, and without further pressure upon, or movement of, either the primary controls or their corresponding trim controls by the pilot or the automatic pilot.
    (amended 2003/11/10; previous version)
  2. (b) Lateral and directional trim. The aeroplane shall maintain lateral and directional trim with the most adverse lateral displacement of the centre of gravity within the relevant operating limitations, during normally expected conditions of operation (including operation at any speed from 1.3 VSR1 to VMO/MMO).
    (amended 2003/11/10; previous version)
  3. (c) Longitudinal trim. The aeroplane shall maintain longitudinal trim during:
    1. (1) A climb with maximum continuous power at a speed not more than 1.3 VSR1, with the landing gear retracted, and the flaps:
      (amended 2003/11/10)
      1. (i) retracted; and
      2. (ii) in the take-off position;
    2. (2) Either a glide with power off at a speed not more than 1.3 VSR1, or an approach within the normal range of approach speeds appropriate to the weight and configuration with power settings corresponding to a 3 degree glidepath, whichever is the most severe, with the landing gear extended, the wing flaps (i) retracted and (ii) extended, and with the most unfavourable combination of centre of gravity position and weight approved for landing; and
      (amended 2005/06/03; previous version)
    3. (3) Level flight at any speed from 1.3 VSR1 to VMO/MMO, with the landing gear and flaps retracted, and from 1.3 VSR1 to VLE with the landing gear extended.
      (amended 2003/11/10)
  4. (d) Longitudinal, directional, and lateral trim. The aeroplane shall maintain longitudinal, directional, and lateral trim (and for lateral trim, the angle of bank shall not exceed five degrees) at 1.3 VSR1 during climbing flight with:
    (amended 2005/06/03; previous version)
    1. (1) The critical engine inoperative;
    2. (2) The remaining engines at maximum continuous power; and
    3. (3) The landing gear and flaps retracted.
  5. (e) Aeroplanes with four or more engines. Each aeroplane with four or more engines shall maintain trim in rectilinear flight with the most unfavourable centre of gravity and at the climb speed, configuration, and power required by 525.123(a) for the purpose of establishing the en route flight paths with two engines inoperative.
    (amended 2005/06/03; previous version)
Stability
525.171 General

The aeroplane must be longitudinally, directionally, and laterally stable in accordance with the provisions of 525.173 through 525.177. In addition, suitable stability and control feel (static stability) is required in any condition normally encountered in service, if flight tests show it is necessary for safe operation.

525.173 Static Longitudinal Stability

Under the conditions specified in 525.175, the characteristics of the elevator control forces (including friction) must be as follows:

(a) A pull must be required to obtain and maintain speeds below the specified trim speed, and a push must be required to obtain and maintain speeds above the specified trim speed. This must be shown at any speed that can be obtained except speeds higher than the landing gear or wing flap operating limit speeds or VFC/MFC, whichever is appropriate, or lower than the minimum speed for steady unstalled flight.

(b) The airspeed must return to within 10 percent of the original trim speed for the climb, approach, and landing conditions specified in 525.175(a), (c), and (d), and must return to within 7.5 percent of the original trim speed for the cruising condition specified in 525.175(b), when the control force is slowly released from any speed within the range specified in paragraph (a) of this section.

(c) The average gradient of the stable slope of the stick force versus speed curve may not be less than 1 pound for each 6 knots.

(d) Within the free return speed range specified in paragraph (b) of this section, it is permissible for the aeroplane, without control forces, to stabilise on speeds above or below the desired trim speeds if exceptional attention on the part of the pilot is not required to return to and maintain the desired trim speed and altitude.

525.175 Demonstration of Static Longitudinal Stability

Static longitudinal stability shall be demonstrated as follows:
(amended 2003/11/10; previous version)

  1. (a) Climb. The stick force curve shall have a stable slope at speeds between 85 and 115 percent of the speed at which the aeroplane:
    (amended 2003/11/10; previous version)
    1. (1) Is trimmed with:
      1. (i) Wing flaps retracted;
      2. (ii) Landing gear retracted;
      3. (iii) Maximum take-off weight; and
      4. (iv) 75 percent of maximum continuous power for reciprocating engines or the maximum power or thrust selected by the applicant as an operating limitation for use during climb for turbine engines; and
    2. (2) Is trimmed at the speed for best rate-of-climb except that the speed need not be less than 1.3 VSR1.
      (amended 2003/11/10; previous version)
  2. (b) Cruise. Static longitudinal stability shall be demonstrated in the cruise condition as follows:
    (amended 2003/11/10; previous version)
    1. (1) With the landing gear retracted at high speed, the stick force curve shall have a stable slope at all speeds within a range which is the greater of 15 percent of the trim speed plus the resulting free return speed range, or 50 knots plus the resulting free return speed range, above and below the trim speed (except that the speed range need not include speeds less than 1.3 VSR1, nor speeds greater than VFC/MFC, nor speeds that require a stick force of more than 50 pounds), with:
      (amended 2003/11/10; previous version)
      1. (i) Wing flaps retracted;
      2. (ii) The centre of gravity in the most adverse position (see 525.27);
      3. (iii) The most critical weight between the maximum take-off and maximum landing weights.
      4. (iv) 75 percent of maximum continuous power for reciprocating engines or, for turbine engines, the maximum cruising power selected by the applicant as an operating limitation (see 525.1521), except that the power need not exceed that required at VMO/MMO; and
      5. (v) The aeroplane trimmed for level flight with the power required in (b)(1)(iv) above.
        (amended 2005/06/03; previous version)
    2. (2) With the landing gear retracted at low speed, the stick force curve shall have a stable slope at all speeds within a range which is the greater of 15 percent of the trim speed plus the resulting free return speed range, or 50 knots plus the resulting free return speed range, above and below the trim speed (except that the speed range need not include speeds less than 1.3 VSR1, nor speeds greater than the minimum speed of the applicable speed range prescribed in (b)(1), nor speeds that require a stick force of more than 50 pounds), with:
      (amended 2005/06/03; previous version)
      1. (i) Wing flaps, centre of gravity position, and weight as specified in (b)(1) of this section;
        (amended 2005/06/03; previous version)
      2. (ii) Power required for level flight at a speed equal to:

(V MO + 1.3 V SR 1)/2 and
(amended 2003/11/10; previous version)

      1. (iii) The aeroplane trimmed for level flight with the power required in (b)(2)(ii) above.
        (amended 2005/06/03; previous version)
    1. (3) With the landing gear extended, the stick force curve shall have a stable slope at all speeds within a range which is the greater of 15 percent of the trim speed plus the resulting free return speed range, or 50 knots plus the resulting free return speed range, above and below the trim speed (except that the speed range need not include speeds less than 1.3 VSR1, nor speeds greater than VLE, nor speeds that require a stick force of more than 50 pounds), with:
      1. (i) Wing flap, centre of gravity position, and weight as specified in (b)(1) above;
        (amended 2005/06/03; previous version)
      2. (ii) 75 percent of maximum continuous power for reciprocating engines or, for turbine engines, the maximum cruising power selected by the applicant as an operating limitation, except that the power need not exceed that required for level flight at VLE; and
      3. (iii) The aircraft trimmed for level flight with the power required in (b)(3)(ii) above.
        (amended 2005/06/03; previous version)
  1. (c) Approach. The stick force curve shall have a stable slope at speeds between VSW and 1.7 VSR1, with:
    (amended 2003/11/10; previous version)
    1. (1) Wing flaps in the approach position;
    2. (2) Landing gear retracted;
    3. (3) Maximum landing weight; and
    4. (4) The aeroplane trimmed at 1.3 VSR1 with enough power to maintain level flight at this speed.
      (amended 2003/11/10)
  2. (d) Landing. The stick force curve shall have a stable slope and the stick force shall not exceed 80 pounds, at speeds between VSW and 1.7 VSR0 with:
    (amended 2005/06/03; previous version)
    1. (1) Wing flaps in the landing position;
    2. (2) Landing gear extended;
    3. (3) Maximum landing weight;
    4. (4) The aeroplane trimmed at 1.3 VSR0 with:
      (amended 2005/06/03; previous version)
      1. (i) Power or thrust off; and
      2. (ii) Power or thrust for level flight.
    5. (5) The aeroplane trimmed at 1.3 VSR0 with power or thrust off.
      (amended 2003/11/10; previous version)

(Change 525-3 (91-11-01))

525.177 Static Lateral-Directional Stability

  1. (a) The static directional stability (as shown by the tendency to recover from a skid with the rudder free) must be positive for any landing gear and flap position and symmetric power condition, at speeds from 1.13 VSR1 up to VFE, VLE, or VFC/MFC (as appropriate for the aeroplane configuration).
    (effective 2013/02/01)
  2. (b) The static lateral stability (as shown by the tendency to raise the low wing in a sideslip with the aileron controls free) for any landing gear and flap position and symmetric power condition, may not be negative at any airspeed (except that speeds higher than VFE need not be considered for flaps extended configurations nor speeds higher than VLE for landing gear extended configurations) in the following airspeed ranges:
    (effective 2013/02/01)
    1. (1) from 1.13 VSR1 to VMO/MMO;
    2. (2) from VMO/MMO to VFC/MFC, unless the divergence is:
      1. (i) gradual;
      2. (ii) easily recognizable by the pilot; and
      3. (iii) easily controllable by the pilot.
  3. (c) The following requirement must be met for the configurations and speed specified in paragraph (a) of this section. In straight, steady sideslips over the range of sideslip angles appropriate to the operation of the aeroplane, the aileron and rudder control movements and forces shall be substantially proportional to the angle of sideslip in a stable sense. This factor of proportionality shall lie between limits found necessary for safe operation. The range of sideslip angles evaluated must include those sideslip angles resulting from the lesser of:
    (effective 2013/02/01)
    1. (1) one-half of the available rudder control input; and
    2. (2) a rudder control force of 180 pounds.
  4. (d) For sideslip angles greater than those prescribed by paragraph (c) of this section, up to the angle at which full rudder control is used or a rudder control force of 180 pounds is obtained, the rudder control forces may not reverse, and increased rudder deflection must be needed for increased angles of sideslip. Compliance with this requirement must be shown using straight, steady sideslips, unless full lateral control input is achieved before reaching either full rudder control input or a rudder control force of 180 pounds; a straight, steady sideslip need not be maintained after achieving full lateral control input. This requirement must be met at all approved landing gear and flap positions for the range of operating speeds and power conditions appropriate to each landing gear and flap position with all-engines-operating.
    (effective 2013/02/01)

(Change 525-3 (91-11-01))

525.181 Dynamic Stability

  1. (a) Any short period oscillation, not including combined lateral directional oscillations, occurring between 1.13 VSR and maximum allowable speed appropriate to the configuration of the aeroplane shall be heavily damped with the primary controls:
    (amended 2003/11/10; previous version)
    1. (1) Free; and
    2. (2) In a fixed position.
  2. (b) Any combined lateral-directional oscillations ("Dutch roll") occurring between 1.13 VSR and maximum allowable speed appropriate to the configuration of the aeroplane shall be positively damped with controls free, and shall be controllable with normal use of the primary controls without requiring exceptional pilot skill.
    (amended 2003/11/10; previous version)

(Change 525-3 (91-11-01))

Stalls
525.201 Stall Demonstration
  1. (a) Stalls shall be demonstrated in straight flight and in 30 degree banked turns with:
    (amended 2003/11/10; previous version)
    1. (1) Power off; and
    2. (2) The power necessary to maintain level flight at 1.5 VSR1 (where VSR1 corresponds to the reference stall speed at maximum landing weight with flaps in the approach position and the landing gear retracted.
      (amended 2003/11/10; previous version)
  2. (b) In each condition required by paragraph (a) of this section, it shall be possible to meet the applicable requirements of 525.203 with:
    (amended 2003/11/10; previous version)
    1. (1) Flaps, landing gear and deceleration devices in any likely combination of positions approved for operation;
    2. (2) Representative weights within the range for which certification is requested;
    3. (3) The most adverse centre of gravity for recovery; and
    4. (4) The aeroplane trimmed for straight flight at the speed prescribed in 525.103(b)(6).
      (amended 2003/11/10; previous version)
  3. (c) The following procedures must be used to show compliance with 525.203:
    1. (1) Starting at a speed sufficiently above the stalling speed to ensure that a steady rate of speed reduction can be established, apply the longitudinal control so that the speed reduction does not exceed one knot per second until the aeroplane is stalled.
    2. (2) In addition, for turning flight stalls, apply the longitudinal control to achieve airspeed deceleration rates up to 3 knots per second.
    3. (3) As soon as the aeroplane is stalled, recover by normal recovery techniques.
  4. (d) The aeroplane is considered stalled when the behaviour of the aeroplane gives the pilot a clear and distinctive indication of an acceptable nature that the aeroplane is stalled. Acceptable indications of a stall, occurring either individually or in combination, are:
    1. (1) A nose-down pitch that cannot be readily arrested;
    2. (2) Buffeting, of a magnitude and severity that is a strong and effective deterrent to further speed reduction; or
    3. (3) The pitch control reaches the aft stop and no further increase in pitch attitude occurs when the control is held full aft for a short time before recovery is initiated.

(Change 525-3 (91-11-01))
(Change 525-7 (96-09-30))

525.203 Stall Characteristics
  1. (a) It must be possible to produce and to correct roll and yaw by unreversed use of the aileron and rudder controls, up to the time the aeroplane is stalled. No abnormal nose-up pitching may occur. The longitudinal control force must be positive up to and throughout the stall. In addition, it must be possible to promptly prevent stalling and to recover from a stall by normal use of the controls.
  2. (b) For level wing stalls, the roll occurring between the stall and the completion of the recovery may not exceed approximately 20 degrees.
  3. (c) For turning flight stalls, the action of the aeroplane after the stall may not be so violent or extreme as to make it difficult, with normal piloting skill, to effect a prompt recovery and to regain control of the aeroplane. The maximum bank angle that occurs during the recovery may not exceed:
    1. (1) Approximately 60 degrees in the original direction of the turn, or 30 degrees in the opposite direction, for deceleration rates up to 1 knot per second; and
    2. (2) Approximately 90 degrees in the original direction of the turn, or 60 degrees in the opposite direction, for deceleration rates in excess of 1 knot per second.

(Change 525-7 (96-09-30))

525.205 (Removed)

(Change 525-3 (91-11-01))

525.207 Stall Warning
  1. (a) Stall warning with sufficient margin to prevent inadvertent stalling with the flaps and landing gear in any normal position shall be clear and distinctive to the pilot in straight and turning flight.
    (amended 2003/11/10; previous version)
  2. (b) The warning shall be furnished either through the inherent aerodynamic qualities of the aeroplane or by a device that will give clearly distinguishable indications under expected conditions of flight. However, a visual stall warning device that requires the attention of the flight crew members within the cockpit is not acceptable by itself. If a warning device is used, it shall provide a warning in each of the aeroplane configurations prescribed in (a) of this section at the speed prescribed in (c) and (d) of this section. Except for showing compliance with the stall warning margin prescribed in (h)(3)(ii) of this section, the stall warning for flight in icing conditions must be provided by the same means as the stall warning for flight in non-icing conditions. aIn addition, a stall warning system, if required, must provide an appropriate warning that is clearly audible to the flight crew members under all foreseeable operating conditions.
    (effective 2014/11/30)

    a
    Canadian variation

    Information Note: Corresponding FAR text for reference:
    (effective 2014/11/30)

    (b) The warning must be furnished either through the inherent aerodynamic qualities of the airplane or by a device that will give clearly distinguishable indications under expected conditions of flight. However, a visual stall warning device that requires the attention of the crew within the cockpit is not acceptable by itself. If a warning device is used, it must provide a warning in each of the airplane configurations prescribed in paragraph (a) of this section at the speed prescribed in paragraphs (c) and (d) of this section. Except for showing compliance with the stall warning margin prescribed in paragraph (h)(3)(ii) of this section, stall warning for flight in icing conditions must be provided by the same means as stall warning for flight in non-icing conditions.
    (effective 2014/11/30)
  3. (c) When the speed is reduced at rates not exceeding one knot per second, stall warning shall begin, in each normal configuration, at a speed, VSW, exceeding the speed at which the stall is identified in accordance with 525.201(d) by not less than five knots or five percent CAS, whichever is greater. Once initiated, stall warning shall continue until the angle of attack is reduced to approximately that at which stall warning began.
    (amended 2003/11/10; previous version)
  4. (d) In addition to the requirement of subsection (c) of this section, when the speed is reduced at rates not exceeding one knot per second, in straight flight with engines idling and at the center of gravity position specified in 525.103(b)(5), VSW, in each normal configuration, shall exceed VSR by not less than three knots or three percent CAS, whichever is greater.
    (amended 2003/11/10; no previous version)
  5. (e) In icing conditions, the stall warning margin in straight and turning flight shall be sufficient to allow the pilot to prevent stalling (as defined in 525.201(d)) when the pilot starts a recovery manoeuvre not less than three seconds after the onset of stall warning. When demonstrating compliance with this paragraph, the pilot shall perform the recovery manoeuvre in the same way as for the aeroplane in non-icing conditions. Compliance with this requirement shall be demonstrated in flight with the speed reduced at rates not exceeding one knot per second, with:
    (amended 2008/10/30; previous version)
    1. (1) The more critical of the take-off ice and final take-off ice accretions defined in Appendix C for each configuration used in the take-off phase of flight;
      (amended 2008/10/30; previous version)
    2. (2) The en route ice accretion defined in Appendix C for the en route configuration;
      (amended 2008/10/30; previous version)
    3. (3) The holding ice accretion defined in Appendix C for the holding configuration(s);
      (amended 2008/10/30; previous version)
    4. (4) The approach ice accretion defined in Appendix C for the approach
      (amended 2008/10/30; previous version)
    5. (5) The landing ice accretion defined in Appendix C for the landing and go-around configuration(s).
      (amended 2008/10/30; previous version)
  6. (f) The stall warning margin shall be sufficient in both non-icing and icing conditions to allow the pilot to prevent stalling when the pilot starts a recovery manoeuver not less than one second after the onset of stall warning in slow-down turns with at least 1.5g load factor normal to the flight path and airspeed deceleration rates of at least 2 knots per second. When demonstrating compliance with this paragraph for icing conditions, the pilot shall perform the recovery manoeuvre in the same way as for the aeroplane in non-icing conditions. Compliance with this requirement shall be demonstrated in flight with:
    (amended 2008/10/30; previous version)
    1. (1) The flaps and landing gear in any normal position;
      (amended 2008/10/30; previous version)
    2. (2) The aeroplane trimmed for straight flight at a speed of 1.3 VSR; and
      (amended 2008/10/30; previous version)
    3. (3) The power or thrust necessary to maintain level flight at 1.3 VSR.
      (amended 2008/10/30; previous version)
  7. (g) Stall warning shall also be provided in each abnormal configuration of the high lift devices that is likely to be used in flight following system failures (including all configurations covered by Aeroplane Flight Manual procedures).
    (amended 2008/10/30; previous version)
  8. (h) For flight in icing conditions before the ice protection system has been activated and is performing its intended function, with the ice accretion defined in Appendix C, Part II(e) of this Chapter, the stall warning margin in straight and turning flight must be sufficient to allow the pilot to prevent stalling without encountering any adverse flight characteristics when:
    (effective 2014/11/30)
    1. (1) the speed is reduced at rates not exceeding one knot per second;
      (effective 2014/11/30)
    2. (2) the pilot performs the recovery manoeuvre in the same way as for flight in non-icing conditions; and
      (effective 2014/11/30)
    3. (3) the recovery manoeuvre is started no earlier than:
      (effective 2014/11//30)
      1. (i) one second after the onset of stall warning if stall warning is provided by the same means as for flight in non-icing conditions; or
      2. (ii) three seconds after the onset of stall warning if stall warning is provided by a different means than for flight in non-icing conditions.
      3. (i) In showing compliance with (h) of this section, if stall warning is provided by a different means in icing conditions than for non-icing conditions, compliance with 525.203 must be shown using the accretion defined in Appendix C, Part II(e) of this Chapter. Compliance with this requirement must be shown using the demonstration prescribed by 525.201, except that the deceleration rates of 525.201(c)(2) need not be demonstrated.
        (effective 2014/11//30)
Ground and Water Handling Characteristics
525.231 Longitudinal Stability and Control
  1. (a) Landplanes may have no uncontrollable tendency to nose over in any reasonably expected operating condition or when rebound occurs during landing or take-off. In addition:
    1. (1) Wheel brakes shall operate smoothly and may not cause any undue tendency to nose over; and
      (amended 2003/11/10; previous version)
    2. (2) If a tail-wheel landing gear is used, it shall be possible, during the take-off ground run on concrete, to maintain any attitude up to thrust line level, at 75 percent of VSR1.
      (amended 2003/11/10; previous version)
  2. (b) For seaplanes and amphibians, the most adverse water conditions safe for take-off, taxiing, and landing, shall be established.
    (amended 2003/11/10; previous version)
525.233 Directional Stability and Control
  1. (a) There may be no uncontrollable ground-looping tendency in 90° cross winds, up to a wind velocity of 20 knots or 0.2 VSR0, whichever is greater, except that the wind velocity need not exceed 25 knots at any speed at which the aeroplane may be expected to be operated on the ground. This may be demonstrated while establishing the 90° cross component of wind velocity required by 525.237.
    (amended 2003/11/10; previous version)
  2. (b) Landplanes must be satisfactorily controllable, without exceptional piloting skill or alertness, in power-off landings at normal landing speed, without using brakes or engine power to maintain a straight path. This may be shown during power-off landings made in conjunction with other tests.
  3. (c) The aeroplane must have adequate directional control during taxiing. This may be shown during taxiing prior to take-offs made in conjunction with other tests.
525.235 Taxiing Condition

The shock absorbing mechanism may not damage the structure of the aeroplane when the aeroplane is taxied on the roughest ground that may reasonably be expected in normal operation.

525.237 Wind Velocities
  1. (a) For landplanes and amphibians, the following applies:
    (amended 2008/10/30; previous version)
    1. (1) A 90-degree cross component of wind velocity, demonstrated to be safe for take-off and landing, shall be established for dry runways and shall be at least 20 knots or 0.2 VSR0, whichever is greater, except that it need not exceed 25 knots.
      (amended 2008/10/30; previous version)
    2. (2) The crosswind component for take-off established without ice accretions is valid in icing conditions.
      (amended 2008/10/30; no previous version)
    3. (3) The landing crosswind component shall be established for:
      (amended 2008/10/30; no previous version)
      1. (i) Non-icing conditions, and
        (amended 2008/10/30; no previous version)
      2. (ii) Icing with the landing ice accretion defined in Appendix C.
        (amended 2008/10/30; no previous version)
  2. (b) For seaplanes and amphibians, the following applies:
    1. (1) A 90-degree cross component of wind velocity, up to which take-off and landing is safe under all water conditions that may reasonably be expected in normal operation, shall be established and shall be at least 20 knots or 0.2 VSR0, whichever is greater, except that it need not exceed 25 knots.
      (amended 2003/11/10; previous version)
    2. (2) A wind velocity, for which taxiing is safe in any direction under all water conditions that may reasonably be expected in normal operation, shall be established and shall be at least 20 knots or 0.2 VSR0, whichever is greater, except that it need not exceed 25 knots.
      (amended 2003/11/10; previous version)
525.239 Spray Characteristics, Control, and Stability on Water
  1. (a) For seaplanes and amphibians, during take-off, taxiing, and landing, and in the conditions set forth in paragraph (b) of this section, there may be no:
    1. (1) Spray characteristics that would impair the pilot's view, cause damage, or result in the taking in of an undue quantity of water;
    2. (2) Dangerously uncontrollable porpoising, bounding, or swinging tendency; or
    3. (3) Immersion of auxiliary floats or sponsons, wing tips, propeller blades, or other parts not designed to withstand the resulting water loads.
  2. (b) Compliance with the requirements of paragraph (a) of this section must be shown:
    1. (1) In water conditions, from smooth to the most adverse condition established in accordance with 525.231;
    2. (2) In wind and cross-wind velocities, water currents, and associated waves and swells that may reasonably be expected in operation on water;
    3. (3) At speeds that may reasonably be expected in operation on water;
    4. (4) With sudden failure of the critical engine at any time while on water; and
    5. (5) At each weight and centre of gravity position, relevant to each operating conditions, within the range of loading conditions for which certification is requested.
  3. (c) In the water conditions of paragraph (b) of this section, and in the corresponding wind conditions, the seaplane or amphibian must be able to drift for five minutes with engines inoperative, aided, if necessary, by a sea anchor.
Miscellaneous Flight Requirements
525.251 Vibration and Buffeting
  1. (a) The aeroplane must be demonstrated in flight to be free from any vibration and buffeting that would prevent continued safe flight in any likely operating condition.
  2. (b) Each part of the aeroplane must be demonstrated in flight to be free from excessive vibration under any appropriate speed and power conditions up to VDF/MDF. The maximum speeds shown must be used in establishing the operating limitations of the aeroplane in accordance with 525.1505.
  3. (c) Except as provided in paragraph (d), there may be no buffeting condition, in normal flight, including configuration changes during cruise, severe enough to interfere with the control of the aeroplane, to cause excessive fatigue to the crew, or to cause structural damage. Stall warning b buffeting within these limits is allowable.
  4. (d) There may be no perceptible buffeting condition in the cruise configuration in straight flight at any speed up to VMO/MMO, except that stall warning buffeting is allowable.
  5. (e) For an aeroplane with MD greater than 6 or with a maximum operating altitude greater than 25,000 feet, the positive manoeuvring load factors at which the onset of perceptible buffeting occurs must be determined with the aeroplane in the cruise configuration for the ranges of airspeed or Mach number, weight, and altitude for which the aeroplane is to be certificated. The envelopes of load factor, speed, altitude, and weight must provide a sufficient range of speeds and load factors for normal operations. Probable inadvertent excursions beyond the boundaries of the buffet onset envelopes may not result in unsafe conditions.

(Change 525-3 (91-11-01))
(Change 525-5 (92-10-30))

525.253 High-Speed Characteristics
  1. (a) Speed Increase and Recovery Characteristics. The following speed increase and recovery characteristics must be met:
    1. (1) Operating conditions and characteristics likely to cause inadvertent speed increases (including upsets in pitch and roll) must be simulated with the aeroplane trimmed at any likely cruise speed up to VMO/MMO. These conditions and characteristics include gust upsets, inadvertent control movements, low stick force gradient in relation to control friction, passenger movement, levelling off from climb, and descent from Mach to airspeed limit altitudes.
    2. (2) Allowing for pilot reaction time after effective inherent or artificial speed warning occurs, it must be shown that the aeroplane can be recovered to a normal altitude and its speed reduced to VMO/MMO, without:
      1. (i) Exceptional piloting strength or skill;
      2. (ii) Exceeding VD/MD VDF/MDF, or the structural limitations; and
      3. (iii) Buffeting that would impair the pilot's ability to read the instruments or control the aeroplane for recovery.
    3. (3) With the aeroplane trimmed at any speed up to VMO/MMO, there must be no reversal of the response to control input about any axis at any speed up to VDF/MDF. Any tendency to pitch, roll, or yaw must be mild and readily controllable, using normal piloting techniques. When the aeroplane is trimmed at VMO/MMO, the slope of the elevator control force versus speed curve need not be stable at speeds greater than VFC/MFC, but there must be a push force at all speeds up to VDF/MDF and there must be no sudden or excessive reduction of elevator control force as VDF/MDF is reached.
    4. (4) Adequate roll capability to assure a prompt recovery from a lateral upset condition must be available at any speed up to VDF/MDF.
      (effective 2013/02/01)
    5. (5) With the aeroplane trimmed at VMO/ MMO, extension of the speedbrakes over the available range of movements of the pilot's control, at all speeds above VMO/MMO, but not so high that VDF/MDF would be exceeded during the manoeuvre, must not result in:
      (effective 2013/02/01)
      1. (i) an excessive positive load factor when the pilot does not take action to counteract the effects of extension;
      2. (ii) buffeting that would impair the pilot's ability to read the instruments or control the aeroplane for recovery; or
      3. (iii) a nose down pitching moment, unless it is small.
  2. (b) Maximum speed for stability characteristics, VFC/MFC. VFC/MFC is the maximum speed at which the requirements of 525.143(g), 525.147(f), 525.175(b)(1), 525.177(a) through (c), and 525.181 shall be met with flaps and landing gear retracted. Except as noted in 525.253(c), VFC/MFC shall not be less than a speed midway between VMO/MMO and VDF/MDF, except that for altitudes where Mach number is the limiting factor, MFC need not exceed the Mach number at which effective speed warning occurs.
    (effective 2013/02/01)
  3. (c) Maximum speed for stability characteristics in icing conditions. The maximum speed for stability characteristics with the ice accretions defined in Appendix C, at which the requirements of 525.143(g), 525.147(e), 525.175(b)(1), 525.177, and 525.181 shall be met, is the lower of:
    (amended 2008/10/30; no previous version)
    1. (1) 300 knots CAS;
      (amended 2008/10/30; no previous version)
    2. (2) VFC; or
      (amended 2008/10/30; no previous version)
    3. (3) A speed at which it is demonstrated that the airframe will be free of ice accretion due to the effects of increased dynamic pressure.
      (amended 2008/10/30; no previous version)

(Change 525-3 (91-11-01))
(Change 525-7 (96-09-30))

525.255 Out-of-Trim Characteristics
  1. (a) From an initial condition with the aeroplane trimmed at cruise speeds up to VMO/MMO, the aeroplane must have satisfactory manoeuvring stability and controllability with the degree of out-of-trim in both the aeroplane nose-up and nose-down directions, which results from the greater of:
    1. (1) A three-second movement of the longitudinal trim system at its normal rate for the particular flight condition with no aerodynamic load (or an equivalent degree of trim for aeroplanes that do not have a power-operated trim system), except as limited by stops in the trim system, including those required by 525.655(b) for adjustable stabilisers; or
    2. (2) The maximum mistrim that can be sustained by the autopilot while maintaining level flight in the high speed cruising condition.
  2. (b) In the out-of-trim condition specified in paragraph (a) of this section, when the normal acceleration is varied from +1 g to the positive and negative values specified in paragraph (c) of this section:
    1. (1) The stick force vs. g curve must have a positive slope at any speed up to and including VFC/MFC; and
    1. (2) At speeds between VFC/MFC and VDF/MDF the direction of the primary longitudinal control force may not reverse.
  3. (c) Except as provided in paragraphs (d) and (e) of this section, compliance with the provisions of paragraph (a) of this section must be demonstrated in flight over the acceleration range:
    1. (1) -1g to +2.5 g; or
    2. (2) 0 g to 2.0 g, and extrapolating by an acceptable method to -1 g and +2.5 g.
  4. (d) If the procedure set forth in paragraph (c)(2) of this section is used to demonstrate compliance and marginal conditions exist during flight test with regard to reversal of primary longitudinal control force, flight tests must be accomplished from the normal acceleration at which a marginal condition is found to exist to the applicable limit specified in paragraph (b)(1) of this section.
  5. (e) During flight tests required by paragraph (a) of this section, the limit manoeuvring load factors prescribed in 525.333 (b) and 525.337, and the manoeuvring load factors associated with probable inadvertent excursions beyond the boundaries of the buffet onset envelopes determined under 525.251(e), need not be exceeded. In addition, the entry speeds for flight test demonstrations at normal acceleration values less than 1 g must be limited to the extent necessary to accomplish a recovery with out exceeding VDF/MDF.
  6. (f) In the out-of-trim condition specified in paragraph (a) of this section, it must be possible from an overspeed condition at VDF/MDF to produce at least 1.5g for recovery by applying not more than 125 pounds of longitudinal control force using either the primary longitudinal control alone or the primary longitudinal control and the longitudinal trim system. If the longitudinal trim is used to assist in producing the required load factor, it must be shown at VDF/MDF that the longitudinal trim can be actuated in the aeroplane nose-up direction with the primary surface loaded to correspond to the least of the following aeroplane nose-up control forces:
    1. (1) The maximum control forces expected in services as specified in 525.301 and 525.397.
    2. (2) The control force required to produce 1.5g.
    3. (3) The control force corresponding to buffeting or other phenomena of such intensity that it is a strong deterrent to further application of primary longitudinal control force.
Date modified: