Secondary Flight Controls

CHAPTER NINE

STUDENT GUIDE FOR T-1A AIRCRAFT SYSTEMS

Spoilers

When the spoiler sections on one wing extend, the spoilers on the opposite wing retract into a

recess below the wing surface in a counter motion. The interconnected control wheels manually

control the spoilers.

Rudder

Full travel range of the rudder is 30 left and right from the neutral position. Movement of the

rudder pedals through a cable and pulley arrangement mechanically controls the rudder.

Rudder Pedal Adjustment

Adjustments are made by turning the rudder pedal adjust handwheel on the handwheel bracket

located on the floor forward of each control column.

Rudder Boost

The autopilot system is armed for automatic rudder boost operation when the rudder boost switch

is set to the ARM position. When armed, boost is invoked by excess differential bleed air

pressure between engines (such as engine out condition). The Flight Control Computers (FCCs)

are fed this pressure differential and provide a rudder boost function signal to the rudder servos

whether the autopilot and yaw damper are engaged or not. The amount of torque applied to the

rudder is proportional to the differential bleed air pressure between the engines. Thus, the

greater the thrust asymmetry, the greater the torque applied for rudder deflection. An amber

RUD BST FAIL annunciator, located on the main annunciator panel, illuminates any time the

rudder boost system is turned off or a failure is detected when the system is armed.

904. SECONDARY FLIGHT CONTROLS

The secondary flight controls (flaps, speed brakes, pitch, roll, and yaw trim) are electrically

operated and controlled by switches located on the flight deck.

Pitch Trim (Adjustable Horizontal Stabilizer)

Aircraft pitch trim is accomplished by varying the position of the adjustable horizontal stabilizer.

There are two modes of operation: normal and emergency. Separate motors actuate the

stabilizer, one for each mode of operation. The autopilot uses the emergency pitch trim motor.

Normal Pitch Trim System

Operating time from full up travel to full down travel is approximately 14 seconds. The

maximum stabilizer trim travel is 12 nose up to 1.5 down.

9-2

FLIGHT CONTROL SYSTEMS