ATA 27 Flight Controls

LEGEND

Procedures Required

(O) – An operational procedure
(M) or (M#) – A maintenance procedure
(O)(M) or (O)(M#) – Both operational and maintenance procedures

Repair Interval Categories

Category A

Items in this category shall be repaired within the time interval specified in the "Remarks or Exceptions" column of the air operator's approved MEL. Whenever the proviso in the "Remarks or Exceptions" column of the MMEL states cycles or flight time, the time interval begins with the next flight. Whenever the time interval is listed as flight days, the time interval begins on the flight day following the day of discovery.

Time Limited Dispatch - Some MMEL's for aircraft that are equipped with FADEC engines have relief that is subject to time limited dispatch expressed as a specific number of engine hours, and will start in accordance with the times established by the engine manufacturer or as indicated in the remarks column of the MMEL. Time limited relief cannot be extended.

Category B

Items in this category shall be repaired within 3 consecutive calendar days excluding the day of discovery.

Category C

Items in this category shall be repaired within 10 consecutive calendar days, excluding the day of discovery.

Category D

Items in this category shall be repaired within 120 consecutive calendar days, excluding the day of discovery. To be considered for placement in Category D, the item must be of an optional nature, or excess equipment which an air operator may, at his/her discretion, deactivate, remove from or install on an aircraft.

To be approved for Category D, the item must meet the following criteria:

  1. the absence of the item does not adversely affect crew member's workload;
  2. the crew members do not rely on the function of that item on a routine or continuous basis; and,
  3. the crew members' training, subsequent habit patterns and procedures do not rely on the use of that item.

Category D relief will generally not be approved for equipment which is considered to increase the level of safety, even if that equipment is of an optional nature.

ITEM:  27-00-1  CONTROL SURFACE POSITION INDICATORS

System and Sequence No. Item Repair
Interval
Category
Number
Installed
Number
required
for
dispatch
Procedures
required
Remarks or Exceptions

Control Surface Position Indicators (for non-fly-by-wire systems)

Conventional Indicators C 2 0 (M)(O)

May be inoperative provided:

a) The affected control surface(s) is visually checked for full, free and correct movement prior to each flight, and

b) The affected indicator is clearly identified as inoperative or covered.

Indication is on Multifunction Display, EICAS or ECAM Type Display C 2 0 (M)(O)

May be inoperative provided:

a) The affected control surface(s) is visually checked for full, free and correct movement prior to each flight, and

b) A placard identifying the inoperative indicator must be affixed to the instrument panel adjacent to the applicable CRT.

DISCUSSION:

References:  nil

There is no design requirement for control surface position indicators.  However, on aircraft with powered control surfaces they are usually incorporated and may be used in the system safety analysis.  The visual check prior to each flight is considered adequate compensation.

FAA Differences:  FAA relief is similar to TCCA.  Additional provisions are included by TCCA for aircraft that use multifunction displays for control surface position indicators.

ITEM:  27-00-2  TAKEOFF CONFIGURATION WARNING SYSTEM

System and Sequence No. Item Repair
Interval
Category
Number
Installed
Number
required
for
dispatch
Procedures
required
Remarks or Exceptions
Takeoff Configuration Warning System   1 1   Must be operative.

DISCUSSION:

References:   AWM 525.703, FAA PL 5 (Rev. 1, 15 Aug. 1997)

In order to avoid accidents which result from improper takeoff configuration and because there is no reliable alternative to the takeoff configuration warning system, this item must be operative.

On aircraft that do not include the system as part of the basis of certification, relief will need to be addressed on an individual basis considering service history, etc.

FAA DifferencesFAA relief is similar to TCCAFAA PL 5 specifically addresses air carrier.  FAA does not include “configuration” in the title.

ITEM:  27-10-1  AILERON AND RUDDER TRIM INDICATORS

System and Sequence No. Item Repair
Interval
Category
Number
Installed
Number
required
for
dispatch
Procedures
required
Remarks or Exceptions
Aileron and Rudder Trim Indicators C - - (O)

May be inoperative provided, prior to each flight, the rudder (aileron) trim is:

a) Visually checked for full, free and correct movement, and

b) Confirmed neutral.

 

DISCUSSION:

References: AWM 523.677(a), 525.677(b)

On some aircraft, such as the DHC-8-400, the (O) procedure will not be sufficient to satisfy the provisos and an (M) procedure will be required.

FAA Differences: FAA assigns cat B for the rudder trim indicator and cat C for the aileron trim indicator on the DHC-8-100/200/300 Series MMEL (at Rev. 17, 3 Nov. 2000).

ITEM:  27-20-1  RUDDER PEDAL ADJUSTMENT

System and Sequence No. Item Repair
Interval
Category
Number
Installed
Number
required
for
dispatch
Procedures
required
Remarks or Exceptions
Rudder Pedal Adjustment C 1 0 (M)

May be inoperative provided:

a) The rudder pedals can be secured in a position which meets individual pilot requirements, and

b) Full and unrestricted movement of the rudder and brake pedal deflection is possible at both pilot stations.

DISCUSSION:

References:  nil

FAA DifferencesFAA relief is identical to TCCA.

ITEM:  27-30-1  STALL WARNING SYSTEM

System and Sequence No. Item Repair
Interval
Category
Number
Installed
Number
required
for
dispatch
Procedures
required
Remarks or Exceptions
Stall Warning System B 1 0 (M)

May be inoperative provided:

a) The inoperative system is deactivated,

b) Flight is conducted in accordance with the AFM CG limitations, and

c) Flight is not conducted in known or forecast icing conditions.

DISCUSSION:

References:  nil

Consideration of aircraft handling qualities and stall characteristics will be a determining factor in assigning the category. A C category may be acceptable.

An inoperative stall warning system may impact other systems such as the related FAST/SLOW indicator and the stick pusher system, appropriate NOTES must be included in the MMEL.

FAA DifferencesFAA relief is identical to TCCA.

ITEM:  27-40-1  CONTROL WHEEL TRIM SWITCHES

System and Sequence No. Item Repair
Interval
Category
Number
Installed
Number
required
for
dispatch
Procedures
required
Remarks or Exceptions
Control Wheel Trim Switches C 2 1   One may be inoperative for the pilot not flying provided the standby pitch trim system is operative.

DISCUSSION:

References:  AWM 525.677

Relief may be granted provided a standby pitch trim system or trim wheel is available and suitably located. Trim capability through the autopilot system or a stability augmentation system is not an acceptable back-up to cater to the next failure, that is, failure of the remaining control wheel trim switch.

FAA Differences:  Similar relief, but TCCA will accept a cat C.

ITEM:  27-40-2  PITCH TRIM POSITION INDICATING SYSTEM

System and Sequence No. Item Repair
Interval
Category
Number
Installed
Number
required
for
dispatch
Procedures
required
Remarks or Exceptions
Pitch Trim Position Indicating System C 1 0 (O)

May be inoperative provided, prior to each flight, the longitudinal trim is visually checked for:

a) Full, free and correct movement, and

b) Appropriate position for takeoff.

DISCUSSION:

References: AWM 523.677(a), 525.677(b)

Relief is not appropriate for large aircraft, especially those with all moving stabilizers, if it is difficult to visually determine the trim position for takeoff.  However, some aircraft have more than one indicator and relief may be permitted provided the faulty indicator is not visible.

Consideration should be given to automatic trim systems wherein trim surface positions would be unknown if this dispatch configuration were permitted.

FAA DifferencesFAA relief is similar to TCCA.

ITEM:  27-50-1  FLAP POSITION INDICATOR

System and Sequence No. Item Repair
Interval
Category
Number
Installed
Number
required
for
dispatch
Procedures
required
Remarks or Exceptions
Flap Position Indicator C 1 0 (O)

May be inoperative provided:

a) Flaps are visually checked for full travel prior to each takeoff,

b) Flap operation is not restricted,

c) Flaps are visually checked for proper setting and no asymmetry prior to each takeoff, and

d) A gated flap pre-select system is installed.

DISCUSSION:

References: AWM 523.699, 525.699

It is not considered reasonable for flight crew members to have to leave the flight deck to perform this check, nor is it considered acceptable to have other crew members perform a check for which they are not qualified. Some aircraft have visual markings on the wing structure that indicate the flap position. 

Notwithstanding the paragraph above, relief has been permitted on B90 type airplanes which do not have special markings to determine flap position. Considerations in granting such relief included stall speed spread zero to full flap, simple flap system, straight wing, “benign” stall characteristics, angle of attack indication and stall warning and protection equipment.

Depending on aircraft configurations, special considerations shall be given to other systems (e.g. takeoff warning, landing gear aural warning systems, etc.) that may rely on normal flap position indicator operation.

For some large aircraft relief for one of two indicators has been permitted with no proviso.

FAA DifferencesFAA relief is identical to TCCA.

ITEM:  27-60-1  LIFT DUMP AND/OR DRAG DEVICE INDICATOR

System and Sequence No. Item Repair
Interval
Category
Number
Installed
Number
required
for
dispatch
Procedures
required
Remarks or Exceptions
Lift Dump and/or Drag Device Indicator B 1 0 (O) May be inoperative provided the lift dump or drag device is verified to be in the selected position.

DISCUSSION:

References:   AWM 525.697, AWM 525.699, AC 525-016 Issue 1

If relief is permitted, an operational procedure may be required to detail how the function of the indicator is transferred to the pilots (e.g. checks, aircraft response, etc.).
Relief for the device indicator will not be provided if that indication is used by the takeoff configuration warning system.

Any warning indication, if installed, may have been required by Airworthiness Manual 525.699 or equivalent.  In granting relief, consideration should be given to other reliable means to determine lift and/or drag device extension.  Relief could also be given if it was shown that inadvertent deployment of the device in all flight regimes was not hazardous (see AC 525-016 Issue 1).

Examples:  757, 767, MD 80 - No relief (TC Supp), A300, DC 9 - Relief permitted

FAA Differences: FAA has no Policy Letter but in general grants relief. TC is more stringent in application of the hazard evaluation principles encompassed in AC 525-016 Issue 1.

Date modified: