Part V - Airworthiness Manual Chapter 522 - Gliders and Powered Gliders

Canadian Aviation Regulations (CARs) 2017-2

Content last revised: 2010/12/01

Preamble

SUBCHAPTERS

  • A (522.1-522.3)
  • B (522.21-522.255)
  • C (522.301-522.597)
  • D (522.601-522.885)
  • E (522.901-522.1193)
  • F (522.1301-522.1449)
  • G (522.1501-523.1589)
  • H (522.1801-523.1857)
  • J (522.1901-523.1947)

(2007/12/30)

SUBCHAPTER C STRUCTURE

Flight Loads (continued)

522.337 Limit Manoeuvring Load Factors

The limit manoeuvring load factors on the V-n diagram (see Figure 1) must have at least the following values:

Category U A
n1 +5.3 +7.0
n2 +4.0 +7.0
n3 -1.5 -5.0
n4 -2.65 -5.0

Figure 1

522.341 Gust Load Factors

  1. (a) In the absence of a more rational analysis, the gust load factors must be computed as follows:

where:

po = density of air at sea-level (kg/m3)

U = gust velocity (m/s)

V = equivalent air speed (m/s)

a = slope of wing lift curve per radian

m = mass of the glider (kg)

g = acceleration due to gravity (m/s2)

S = design wing area (m2)

k = gust alleviation factor calculated from the following formula:

where:

(non-dimensional glider mass ratio)

where:

p = density of air (kg/m3) at the altitude considered

lm = mean geometric chord of wing (m)

  1. (b) The value of n calculated from the expression given above need not exceed:

522.345 Loads with Air Brakes and Wingflaps Extended

  1. (a) Loads with air brakes extended

    1. (1) The glider structure including airbrake system, must be capable of withstanding the most unfavourable combination of the following parameters:

Equivalent Airspeed VD (EAS)
Air brakes from the retracted to the fully extended position
Manoeuvring load factor from –1.5 to 3.5
(amended 2007/07/16)
    1. (2) The horizontal tail load is assumed to correspond to the static condition of equilibrium.

    2. (3) In determining the spanwise load distribution, changes in this distribution due to the presence of the air brakes must be accounted for.

  1. (b) Load with wing-flaps extended. If wing-flaps are installed, the glider must be assumed to be subjected to manoeuvres and gusts as follows:

    1. (1) With wing-flaps in all landing settings, at speeds up to VF:

      1. (i) manoeuvring up to a positive limit load factor of 4.0;

      2. (ii) positive and negative gusts of 7.5 m/s acting normal to the flight path.

    2. (2) With wing-flap positions from the most positive en-route setting to the most negative setting, the manoeuvring conditions of 522.333(b) and the gust conditions of 522.333(c), except that the following need not be considered:
      (amended 2007/07/16)

      1. (i) speeds greater than the VF appropriate to the wing-flap setting;

      2. (ii) manoeuvring load factors corresponding to points above the line AD or below the line GE of Figure 1.
        (amended 2007/07/16)

  2. (c) Speed limiting flaps. If wing-flaps are to be used as a drag-increasing device for the purpose of speed limitation (air-brake) conditions specified in 522.345(a) must be met for all wing-flap positions.

  3. (d) When an automatic wing-flap load limiting device is used, the glider must be designed for the critical combination of air speed and wing-flap position allowed by that device.

(Change 522-1 (87-08-31))

522.347 Unsymmetrical Flight Conditions

The glider is assumed to be subjected to the unsymmetrical flight conditions of 522.349 and 522.351. 522.351 Unbalanced aerodynamic moments about the c.g. must be reacted in a rational or conservative manner, considering the principal masses furnishing the reacting inertia forces.

522.349 Rolling Conditions

The glider must be designed for the rolling loads resulting from the aileron deflections and speeds specified in 522.455 in combination with a load factor of at least two-thirds of the positive manoeuvring load factors prescribed in 522.337.

522.351 Yawing Conditions

The glider must be designed for yawing loads on the vertical tail surface specified in 522.441 and 522.443.

522.361 Engine Torque

  1. (a) The engine mount and its supporting structure must be designed for the effects of:

    1. (1) the limit torque corresponding to take-off power and propeller speed, acting simultaneously with 75% of the limit loads from flight condition A of 522.333(b);

    2. (2) the limit torque corresponding to the maximum continuous power and propeller speed, acting simultaneously with the limit loads from flight condition A of 522.333(b).

  2. (b) For reciprocating engines the limit torque to be accounted for in 522.361(a) is obtained by multi plying the mean torque by one of the following factors:

    1. (1) 1.33 for engines with 5 or more cylinders;

    2. (2) 2 for engines with 4 cylinders;

    3. (3) 3 for engines with 3 cylinders;

    4. (4) 4 for engines with 2 cylinders;

522.363 Side Load on Engine Mount

  1. (a) The engine mount and its supporting structure must be designed for a limit load factor in a lateral direction, for the side load on the engine mount, of not less than one-third of the limit load factor for flight condition A (1/3n1).

  2. (b) The side load prescribed in (a) may be assumed to be independent of other flight conditions.

522.371 Gyroscopic Loads

For powered gliders of airworthiness Category A, the engine mount and its supporting structure must be designed for gyroscopic loads resulting from maximum continuous r.p.m.

522.375 Winglets

  1. (a) When winglets are installed the glider must be designed for -

    1. (1) The side loads due to maximum sideslip angle of the winglet at VA;

    2. (2) Loads resulting from gusts acting perpendicularly to the surface of the winglet at VB and VD;

    3. (3) Mutual interaction effects of winglets and wing on aerodynamic loads;

    4. (4) Hand forces on the winglets; and

    5. (5) Loads due to wingtip landing as specified in 522.501, if the winglet can touch the ground.

    6. (b) In the absence of more rational analysis the loads must be computed as follows:

    7. (1) The lift at the winglets due to sideslip at VA -

where: CLmax = maximum lift coefficient of winglet profile

SW = area of winglet

  1. (2) The lift of the winglets due to lateral gust at VB and VD -

where: U = lateral gust velocity at the values as described in 522.333(c)

aW = slope of winglet lift curve per radian

k = gust alleviation factor as defined in 522.443(b)

The above described load LWg need not exceed the value

  1. (3) Hand forces of 15 daN must be assumed to act at the tip of the winglet -

    1. (i) In horizontal inboard and outboard direction parallel to the spanwise axis of the wing; and

    2. (ii) In horizontal forward and backward direction parallel to the longitudinal axis of the fuselage.

In addition, the rigging loads as specified in 522.591 must be applied if the winglet plane is not normal to the plane of the wing.

(Change 522-2 (93-06-30))

Control Surfaces and Systems

522.395 Control System Loads

  1. (a) Each flight control system, including stops, and its supporting structure must be designed for the loads corresponding to at least 125% of the computed hinge moments of the movable control surfaces in the conditions prescribed in 522.415 through 522.455. In computing the hinge moments reliable aerodynamic data must be used. The effects of tabs must be taken into account. In no case must the loads in any part of the system be less than those resulting from the application of 60% of the pilot efforts specified in 522.397(a).

  2. (b) Pilot forces used for design are assumed to act at the appropriate control grips or pads as they would in flight, and to be reacted at the attachments of the control system to the control surface horns.

(Change 522-1 (87-08-31))

522.397 Loads Resulting from Limit Pilot Forces

  1. (a) In addition to 522.395(a) the control systems for the direct control of the glider about its longitudinal, lateral, or yaw-axis (main control system) and other control systems affecting flight behaviour and supporting points must be designed to withstand as far as to the stops (these included) limit loads arising from the following pilot forces:

Control Pilot Force
daN
Method Of Force Application Assuming Single Lever Control Systems

Elevator

35

Push and pull handgrip of control stick

Ailerons

20

Move handgrip of control stick sideways

Rudder

90

Apply forward pressure on one rudder pedal
Air brakes 35 Push and pull handgrip of control lever
Spoilers

Wng-flaps


Towing cable

35

Pull control handle
release
  1. (b) the rudder control system must be designed to a load of 100 daN per pedal acting simultaneously on both pedals in forward direction.

(Change 522-1 (87-08-31))

522.399 Dual Control Systems

Dual control systems must be de signed for:

  1. (a) the pilots acting together in the same direction; and

  2. (b) the pilots acting in opposition, each pilot applying 0.75 times the load specified in 522.397(a).

522.405 Secondary Control Systems

Secondary control systems such as those for landing gear retraction or extension, trim control, etc., must be designed for supporting the maximum forces that a pilot is likely to apply to those controls.

522.411 Control System Stiffness and Stretch

  1. (a) The amount of movement available to the pilot of any aerodynamic control surface may not, in any condition of flight, be excessively reduced by elastic stretch of the control circuits.
    If there are cables in the system and tension can be adjusted, the minimum value must be used for demonstrating compliance with all appropriate requirements.

  2. (b) For cable operated systems, the allowable rigging tension in the cables must be established, taking into consideration the variations in temperature (see 522.689) which may occur.

(Change 522-1 (87-08-31))

522.415 Ground Gust Conditions

The control system from the control surfaces to the stops or when installed the arresting devices must be designed for limit loads corresponding to hinge moments calculated from the expression:

MR= k lR SR q

where:

MR = limit hinge moment

lR = mean chord of control surface aft of hinge line

SR = area of control surface aft of hinge line

q = dynamic pressure corresponding to an air speed of 100 km/h

k = limit hinge moment factor due to ground gust, taken from the following table:

Control
Surface
K Remarks
Aileron ±0.75
Control column secured in mid-position
±0.50 Ailerons at full travel: + moment at the one, moment at the other aileron
Elevator ±0.75 Elevator fully up (-) or fully down (+) or in the position in which it can be locked
Rudder ±0.75 Rudder at full travel right or left, or locked in neutral

Horizontal Tail Surfaces

522.421 Balancing Loads

  1. (a) A horizontal tail balancing load is the load necessary to maintain equilibrium in any specified flight condition with no pitching acceleration.

  2. (b) The horizontal tail must be designed for the balancing loads occurring at any point of the limit manoeuvring envelope and in the air-brake and wing-flap positions as specified in 522.333 and 522.345.

522.423 Manoeuvring Loads

The horizontal tail must be designed for the most severe loads likely to occur in pilot-induced pitching maneuvers, at all speeds up to VD.
(amended 2007/07/16)

522.425 Gust Loads

In the absence of a more rational analysis, the horizontal tail loads must be computed as follows:

where:

P = horizontal tail load (N)

Po = horizontal tail balancing load acting on the horizontal tail before the appearance of the gust (N)

po = density of air at sea-level (kg/m3)

St = area of horizontal tail (m2)

ah = slope of horizontal tail lift curve per radian

U = gust speed (m/s)

kH = gust factor. In the absence of a rational analysis the same value may be taken as for the wing.

V = speed of flight (m/s)

 = rate of change of downwash angle with wing angle of attack

(Change 522-1 (87-08-31))

522.427 Unsymmetrical Loads for Powered Glider

The slipstream effect on fixed surfaces and on rudder loads must be accounted for if such loading is to be expected.

(Change 522-1 (87-08-31))

Vertical Tail Surfaces

522.441 Manoeuvring Load

The vertical tail surfaces must be designed for manoeuvring loads imposed by the following conditions:

  1. (a) At speed the greater of VA and VT, full deflection of the rudder.

  2. (b) At speed VD, one-third of full deflection of the rudder.

522.443 Gust Loads

  1. (a) Vertical tail surfaces must be designed to withstand lateral gusts to the values described in 522.333(c).

  2. (b) In the absence of a more rational analysis, the gust load must be computed as follows:

where:

Pf = gust load (N)

av = slope of vertical tail lift curve per radian

Sf = area of vertical tail (m2)

ro = density of air at sea-level kg/m3)

V = speed of flight (m/s)

U = gust speed (m/s)

k = gust factor, should be taken as 1.2

Supplementary Conditions for Tail Surfaces

522.447 Combined Loads on Tail Surfaces

  1. (a) The unsymmetrical distribution of the balancing load on the horizontal tail which arises in flight conditions A and D of the V-n envelope shall be combined with the appropriate manoeuvring load on the vertical surface as specified in 522.441 acting in such a direction as to increase the rolling torque.

  2. (b) 75% for Category U and 100% for Category A of the loads according to 522.423 for the horizontal tail and 522.441 for the vertical tail must be assumed to be acting simultaneously.

(Change 522-2 (93-06-30))

522.449 Additional Loads Applicable to V-tails

A glider with V-tail, must be designed for a gust acting perpendicularly with respect to one of the tail surfaces at speed VB.

Ailerons

522.455 Ailerons

The ailerons must be designed for control loads corresponding to the following conditions:

  1. (a) at speed the greater of VA and VT the full deflection of the aileron; and

  2. (b) at speed VD, one-third of the full deflection of the aileron.

Ground Loads

522.471 General

The limit ground loads specified in this Subchapter are considered to be external loads and inertia forces that act upon a glider structure. In each specified ground load condition, the external reactions must be placed in equilibrium with the linear and angular inertia forces in a rational or conservative manner.

522.473 Ground Load Conditions and Assumptions

  1. (a) The ground load requirements of this Subchapter, must be complied with at the design maximum weight.

  1. (b) The selected limit vertical inertia load factor at the c.g. of the glider for the ground load conditions prescribed in this Subchapter:
    (amended 2007/07/16)

    1. (1) may not be less than that which would be obtained when landing with a descent velocity of 1.77 m/s;
      (amended 2007/07/16)

    2. (2) may not be less than 3.
      (amended 2007/07/16)

    3. (c) Wing lift balancing the weight of the glider may be assumed to exist throughout the landing impact and to act through the c.g. The ground reaction load factor may be equal to the inertia load factor minus one.

522.477 Landing Gear Arrangement

522.479 through 522.499 apply to gliders with conventional arrangements of landing gear. For unconventional types it may be necessary to investigate additional landing conditions depending on the arrangement and design of the landing gear units.

(Change 522-1 (87-08-31))

522.479 Level Landing Condition

  1. (a) For a level landing, the glider is assumed to be in the following attitude.

    1. (1) For gliders with a tail skid and/or wheel, a normal level flight attitude.

    2. (2) For gliders with nose wheels, attitudes in which -

      1. (i) The nose and main wheels contact the ground simultaneously; and

      2. (ii) The main wheels contact the ground and the nose wheel is just clear of the ground.

  2. (b) The main gear vertical load component PVM must be determined to the conditions in 522.725.

  3. (c) The main gear vertical load component PVM must be combined with a rearward acting horizontal component PH so that the resultant load acts at an angle of 30° with the vertical.
    (amended 2007/07/16)

  4. (d) For gliders with nose wheels the vertical load component PVN on the nose wheel in the attitude of sub-paragraph (a)(2)(i) of this paragraph must be computed as follows and must be combined with a rearward acting horizontal component according to sub-paragraph (c) of this paragraph taking into account 522.725(a):
    (amended 2007/07/16)

PVN = 0.8 mg

where:

m =mass of glider (kg)

g =acceleration of gravity (m/s2).

(Change 522-1 (87-08-31))

522.481 Tail-down Landing Conditions

For design of tail skid and affected structure and empennage including balancing weight attachment, the tail skid load in a tail down landing (main landing gear free from ground) must be calculated as follows:

where:

P = tail skid load (N)

m = mass of the glider (kg)

g = acceleration of gravity (m/s2)

iy = radius of gyration of the glider (m)

L = distance between tail skid and glider c.g. (m)

(Change 522-1 (87-08-31))

522.483 One-wheel Landing Condition

If the two wheels of a main landing gear arrangement are laterally separated, the conditions under 522.479(a)(2), (b) and (c) must be applied also to each wheel separately taking into account limiting effects of bank. In the absence of a more rational analysis the limit kinetic energy must be computed as follows:
(amended 2007/07/16)

A = ½ mred Vv2

where:

 Vv = rate of descent
(amended 2007/07/16)

m =mass of the glider (kg)

a = half the track (m)

ix =radius of gyration of the glider (m)

(Change 522-1 (87-08-31))

522.485 Side Load Conditions

A side load acting on one side of the main landing gear (both from right and left) normal to the plane of symmetry at the centre of the contact area of the tire or skid with the ground, must be assumed. The applied load is equal to 0.3 PV and must be combined with a vertical load of 0.5 PV where PV is the vertical load determined in accordance with 522.473.
(amended 2007/07/16)

522.497 Tail Skid Impact

  1. (a) Except as provided in (b), if the c.g. of the unloaded glider in side view is situated behind the ground contact area of the main landing gear, the rear portion of the fuselage, the tail skid and the empennage must be designed to withstand the loads arising when the tail landing gear is raised to its highest possible position, consistent with the main wheel remaining on the ground, and is then released and allowed to fall freely.

  2. (b) If the c.g. in all loading conditions is situated behind the ground contact area of the main landing gear (a) need not be applied.

522.499 Supplementary Conditions for Nose Wheels

In determining the ground loads on the nose wheel and affected supporting structures, and assuming that the shock absorber and tyre are in their static positions, the following conditions must be met:

  1. (a) For forward loads, the limit force components at the axle must be:

    1. (1) A vertical component of 2.25 times the static load on the wheel; and

    2. (2) A forward component of 0.4 times the vertical component.

  2. (b) For side loads, the limit force components at the ground contact must be:

    1. (1) A vertical component of 2.25 times the static load on the wheel; and

    2. (2) A side component of 0.7 times the vertical component.

(Change 522-1 (87-08-31))

522.501 Wing-tip Landing

There must be means to ensure that ground loads acting at the wing tips are adequately resisted. A limit load T=40 daN must be assumed to act rearward at the point of contact of one wing-tip with the ground, in a direction parallel to the longitudinal axis of the glider, the yawing moment so generated must be balanced by side load R at the tail skid/wheel or nose skid/wheel (see Figure 4).

(Change 522-1 (87-08-31))

Emergency Landing Conditions

522.561 General

  1. (a) The glider although it may be damaged in emergency landing conditions must be designed as prescribed in this paragraph to protect each occupant under those conditions.

  1. (b)The structure must be designed to give each occupant every reasonable chance of escaping serious injury in a crash landing when proper use is made of belts and harnesses provided for in the design, in the following conditions:

    1. (1) The occupant experiences, separately, ultimate inertia forces corresponding to the accelerations shown in the following:

Upward

7.5 g
(amended 2010/05/27)
Forward

15.0 g
(amended 2010/05/27)

Sideward 6.0 g
(amended 2010/05/27)
Downward 9.0 g
(amended 2010/05/27)
    1. (2) An ultimate load of 9 times the weight of the glider acting rearwards and upward at an angle of 45o to the longitudinal axis of the glider and sideward at an angle of 5o acts on the forward portion of the fuselage at a suitable point not behind the pedals.
      (amended 2010/05/27)

  1. (c) Each glider with a retractable landing gear must be designed to protect each occupant in a landing with wheel(s) retracted under the following conditions:

    1. (1) a downward ultimate inertia force corresponding to an acceleration of 3g;

    2. (2) a coefficient of friction of 0.5 at the ground.

  2. (d) Except as provided in 522.787, the supporting structure must be designed to restrain, under loads up to those specified in subparagraph (b)(1) of this paragraph each item of mass that could injure an occupant if it came loose in a crash landing.
    (amended 2010/05/27)

  3. (e) For a powered glider with the engine located behind and above the pilot’s seat, an ultimate inertia load of 15g in the forward direction must be assumed.

(Change 522-1 (87-08-31))

Towing and Launching Loads

522.581 Aerotowing

  1. (a) The glider must be initially assumed to be in stabilized level flight at speed VT with a cable load acting at the launching hook in the following directions:

    1. (1) horizontally forwards;

    2. (2) in plane of symmetry forwards and upwards at an angle of 20° with the horizontal;

    3. (3) in plane of symmetry forwards and downwards at an angle of 40° with the horizontal; and

    4. (4) horizontally forwards and sidewards at an angle of 30° with the plane of symmetry.

  1. (b) With the glider initially assumed to be subjected to the same conditions as specified in 522.581(a), the cable load due to surging suddenly increases to Qnom assuming the use of a textile rope.
    (amended 2007/07/16)

    1. (1) The resulting cable load increment must be balanced by linear and rotational inertia forces. These additional loads must be superimposed on those arising from the conditions of 522.581(a).

    2. (2) Qnom is the rated ultimate strength of the towing cable (or weak link if employed). For the purpose of these requirements it must be assumed to be at not less than 1.3 times the glider maximum weight and not less than 500 daN.

522.583 Winch-launching

  1. (a) The glider must be initially assumed to be in level flight at speed VW with a cable load acting at the launching hook in a forward and downward direction at an angle ranging from 0° to 75° with the horizontal.
    (amended 2007/07/16)

  2. (b) The cable load must be determined as the lesser of the following two values:

    1. (1) 1.2 Qnom as defined in 522.581(b), or
      (amended 2007/07/16)

    2. (2) the loads at which equilibrium is achieved, with either:

      1. (i) the elevator fully deflected in upward direction, or

      2. (ii) the wing at its maximum lift.
        A horizontal inertia force may be assumed to complete the equilibrium of horizontal forces.

  3. (c) In the conditions of 522.583(a), a sudden increase of the cable load to the value of 1.2 Qnom as defined in 522.581(b), is assumed. The resulting incremental loads must be balanced by linear and rotational inertia forces.
    (amended 2007/07/16)

522.585 Strength of Launching Hook Attachment

  1. (a) The launching hook attachment must be designed to carry a limit load of 1.5 Qnom, as defined in 522.581(b), acting in the directions specified in 522.581 and 522.583.
    (amended 2007/07/16)

  2. (b) The launching hook attachment must be designed to carry a limit load equal to the maximum weight of the glider, acting at an angle of 90° to the plane of symmetry.

Other Loads

522.591 Rigging and De-rigging Loads

A rigging limit load of plus and minus twice the wing-tip reaction, determined when either a semi-span wing is simply supported at root and tip or when the complete wing is simply supported at the tips, where this would be representative of the rigging procedure, must be assumed to be applied at the wing tip and reacted by the wing when supported by a reaction and couple at the wing root.

(Change 522-1 (87-08-31))

522.593 Hand Forces at the Horizontal Tail Surfaces

A limit hand force of 3% of the design maximum weight of the glider but not less than 15 daN must be assumed to act on either tip of the horizontal tail surface:

  1. (a) in the vertical direction;

  2. (b) in the horizontal direction, parallel to the longitudinal axis.

  3. (Change 522-1 (87-08-31))

522.595 Load on the Attachment Point of the Parachute Ripcord

The attachment point for the parachute ripcord (if provided) must be designed for a limit load of 300 daN acting in all possible directions.

522.597 Loads from single masses

The attachment means for all single masses, which are part of the equipment of the glider, must be designed to withstand loads corresponding to the maximum design load factors to be expected from the established flight and ground loads.

Date modified: