FLIGHT CONTROLS - DESCRIPTION AND OPERATION

1. General

A. The primary flight controls are the ailerons, elevators, and rudder (Figure 1). These hydraulicallypowered control surfaces provide flight control in roll, pitch, and yaw. The auxiliary flight controls are
the trailing edge flaps, leading edge flaps and slats, the spoilers, and an adjustable horizontal
stabilizer.
B. Lateral (roll) trim is provided by repositioning the aileron null detent to deflect the ailerons.
Longitudinal (pitch) trim is provided by positioning the adjustable horizontal stabilizer. Directional
(yaw) trim is provided by repositioning rudder neutral to deflect the rudder.

2. Roll Control System

A. The roll (lateral) control surfaces consist of the two ailerons and the four flight spoilers. These surfaces are controlled by rotation of the captain's and first officer's control wheels (Figure 2). With hydraulic power on, the control wheel forces are provided by an artifical feel mechanism as all these surfaces are fully hydraulic powered. Control signals from the pilots' control wheels are transmitted through the aileron control system to the control valves on the two aileron power control units (Figure 3). These power control units are supplied with hydraulic power, one from system A and the other from system B. Aileron hydraulic supplies are controlled by the flight controls shutoff valve in each flight controls hydraulic modular package (Figure 4 and Figure 5). Switches for these valves are on the pilots' overhead panel. The aileron power control units are interchangeable with the elevator power control units and are located in the left wheel well. The aileron power control units drive a bus cable system connected to the ailerons by quadrants and pushrods. Balance tabs and balance panels aerodynamically reduce the forces required for aileron movement. In the event of hydraulic failure, motion of the pilots' control wheels mechanically positions the ailerons. B. Lateral (roll) trim is accomplished by the aileron trim control switches (Figure 2) located on the control stand. An electrical actuator in the left wheel well repositions the artificial feel and centering mechanism null detent. This shift of aileron control system null detent provides trim correction by positioning the ailerons. C. Flight spoilers and ground spoilers are located on the upper surface of the wing. Two flight spoilers are outboard of each nacelle. Two ground spoilers are outboard of the flight spoilers, and one ground spoiler is inboard of each nacelle. The flight spoilers are hydraulically actuated in response to inputs from the aileron control system. The flight spoilers raise on the wing with up aileron and remain faired on the wing with down aileron. Flight spoiler motion is in proportion to aileron movement. One spoiler actuator hydraulically positions each flight spoiler panel. Hydraulic system A provides power for spoilers 3 and 6. D. Hydraulic system B provides power for spoilers 2 and 7. The flight spoilers may be deactivated by the spoiler shutoff valves in the flight controls hydraulic modular packages (Figure 4). These valves are controlled by spoiler system A and B switches on the pilots' overhead panel (Figure 5). All flight spoilers may also be used as speed brakes by aft movement of the speed brake control lever (Figure 2). The speed brake control lever actuates the spoiler control system to cause all the flight spoiler panels to raise in unison. The flight spoilers will still respond to aileron inputs when being used as speed brakes. With speed brakes on and the airplane on the ground, hydraulic system A will power the ground spoilers 0, 1, 4, 5, 8, and 9 to full up position.