ATR 42 Model : 400/500
PITCH
FLIGHT CONTROLS
P 1
NOV 00
001
1.09
.
30
30.1 DESCRIPTION
(See schematic p7/8)
Each control column mechanically drives the associated elevator and, through a pitch
coupling mechanism, the other elevator and the opposite control column.
In case of jamming, pitch control will be recovered by applying on both control columns a
differential force (52daN) disengaging the pitch coupling system.
The non affected channel allows the aircraft to be operated safety. System recoupling has
to be performed on ground.
Pitch uncoupling generates PITCH DISCONNECT" red alert.
Control column travel : 11.25º up, 6.75º down.
Elevators travel : 23ºup, 13º down
Elevators automatic tab travel 60 % of the pitch control course.
Pitch trim is performed by offsetting both tabs neutral position.
Normal trim (control column) and STBY trim (pedestal) supply appropriate part of each
actuator.
Each trim tab is activated by a dedicated actuator. The two actuators are synchronized by
a flexible shaft.
In case of pitch tabs desynchronization :
- An alert is generated by the CCAS
- Normal and STBY pitch trim control are inoperative
- AP disconnects
Trim tab travel, displayed on the pitch trim position indicator is added to the automatic tab
travel.
Elevators trim controlled tab travel : 9º up, 4º down
Full pitch trim travel requires about 30s in normal and in STBY control.
A stick pusher and a stick shaker are provided, preventing the aircraft from reaching a
critical angle of attack. When the detected incidence becomes too high, the MFC sends a
signal to an electric actuator which shakes the control column at stall alert thresholds.
If angle of attack keeps increasing, a further threshold is reached and the MFC activates
the stick pusher ; the complete pitch control linkage assembly is pushed forward.
Note : There are two stick shakers, one for each control column but only one stick pusher
actuator located on the captain pitch channel. In case of pitch uncoupling when the
pusher triggering angle of attack is reached, only the captain control column is
pushed forward.
AA
RR
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01/07//2018 REV 1 These notes are not revised after issue For Training Purposes Only
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