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ATR 42-500 > Flight Controls > Flashcards

Flashcards in Flight Controls Deck (15)
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Roll Control and Trim

Achieved by 2 control wheels that travel +/-87* and translates to +/-14* aileron travel.
Trim is accomplished by varying the neutral position setting of the left aileron spring tab, electrically activated from a twin control switch. Tab travels+/-6.7* and full travel time of 15s.


Spoiler Indicators

When illuminated, each blue light indicates the associated spoiler is not in the retracted position.


Pitch Control

2 control columns mechanically drive their associated elevator and through a coupling mechanism, the other elevator and the opposite control column. In case of jamming, applying differential force will uncouple the system. Uncoupling the system generates a PITCH DISCONNECT red warning.
Column travel: +11.25* to -6.75*
Elevator travel: +23* to -13*


Pitch Trim Control

Pitch trim is achieved by offsetting both tabs neutral position. Each trim tab is activated by a dedicated actuator and the 2 are synchronized by a flexible shaft. If desync occurs, CCAS alert; Norm and STBY trim are unavailable and the AP disconnects.
Trim tab travel: +9* to -4*
Takeoff range: +4.5* to -1.5*
Full travel time: 30s in NORM and STBY
Operation of NORM or STBY will disconnect the AP.


Flight Control System

The control of the aircraft on the three axes is achieved by:
-1 aileron (spring-tab equipped) and 1 spoiler on each wing
-2 elevators (servo-tab equipped)
-1 rudder (spring-tab equipped)
Spoilers are actuated with Blue Hydraulic pressure.
All others are mechanically actuated.

Wing flaps are provided in 2 parts (inboard and outboard) mechanically linked and actuated with Blue Hydraulic pressure.


Stick Shaker System

There are 2 stick shakers, 1 for each control column, and only 1 stick pusher on the captain side column. The pusher is unavailable in disconnect ops with a captain side jam.
Stick pusher/shaker may be selected off, the stall warning aural alert is also deactivated.


Yaw Control System

Consists of a rudder, rudder pedals, a TLU, an RCU, a damper and trim system. The rudder is spring tab equipped for ease of use.



Travel Limitation Unit automatically reduces rudder pedal travel at high speed to prevent damaging rudder travel. ADC1/2 enable the TLU at 195kts in the acceleration and disables it at 190kts in the deceleration. This may also be achieved manually through the TLU switch.



Releasable Centering Unit is provided to enable rudder stabilization when no action is applied to the pedals (keeps the pedals centered)


Yaw Damper

Limits rudder travel speed in flight and limits excessive movement on the ground to avoid damage to the stops.


Yaw Trim Control

Performed by offsetting the spring tab zero position. Electrically controlled units of motor displacement are displayed on the position indicator +/-3 dots and full travel time is 15s.


Flap System

Inboard/outboard flaps on each wing work together to augment lift. Flap settings are 0*, 15*, 25*, 35* and intermediate settings are unavailable. Flaps are electrically controlled by the lever and hydraulically actuated by the flap valve and 4 actuators.


Flap Asym and UNLK

Possible asymmetry is sensed by 2 flap position transmitters and the MFC when the angle is 6.7*. The flaps stay in the current position and the control lever has no effect on the system.

FLAP UNLK alert is provided for indication of spurious retraction. The alert is triggered by >3* retractions.


Flap Position Indicator

Shows flap position and blue EXT flag indicates the flap valve is hydraulically commanding flap extension. If the EXT flag appears when flaps are extended, there is a leak in the flaps hydraulic circuit.


Gust Lock System

Protects flight control surfaces on the ground. Elevator is mechanically locked, ailerons are electro-mechanically locked, the yaw damper protects the rudder. The idle gate prevents take off with the gust lock engaged or excessive power setting in hotel mode.