2A-27-20: Pitch Flight Controls System:
1. General Description:
The elevators are manually and electrically controlled, mechanically actuated and
hydraulically boosted. Elevator travel ranges from 24 degrees trailing edge up to
13 degrees trailing edge down. Elevator movement is visually depicted on the
FLIGHT CONTROLS synoptic page.
An elevator trim tab is installed on each elevator. Pitch trim position is displayed
on the FLIGHT CONTROLS synoptic page.
Aircraft pitch is accomplished by movement of the control columns which transmit
motion through conventional mechanical linkage (cables, cranks and pushrods) to
displace the elevator. Hydraulic boost to assist inputs from the control columns is
provided by a dual hydraulic boost actuator. The dual hydraulic actuator contains
two pistons; one piston is powered by the Left Hydraulic System (L SYS), and the
other by the Right Hydraulic System (R SYS). During normal flight conditions, the
elevator actuator is powered simultaneously by L SYS and R SYS at 3000 psi
each. The actuators feature automatic hardover prevention. If a hardover occurs
for over 0.5 second, hydraulic pressure to the actuator will be shut off.
There are two complete sets of elevator controls. Normally, elevator controls are
connected to each other and this duplication is transparent to the flight crew. In
Flight Controls System Components
Figure 2
OPERATING MANUAL
PRODUCTION AIRCRAFT SYSTEMS 2A-27-00
Page 5
May 22/01
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