GRUMMAN AMERICAN
FOR TRAINING USE ONLY – SECTION 7
MODEL GA‐7/COUGAR
AIRPLANE & SYSTEMS DESCRIPTIONS
7‐8
Issued: April 10, 1978
ELEVATOR TRIM SYSTEM (Figure 7‐3)
The elevator trim tab is a bonded structure composed of ribs, spars, and skin. The trim tab forms the inboard
portion of the elevator trailing edge, and is connected to the elevator with a piano‐type hinge. A horn assembly
extending from the underside of the trim tab is connected to the control system by an adjustable pushrod
extending through the elevator structure.
As the elevator trim tab control wheel is rotated, its angular displacement is transmitted to a chain and sprocket
located within the right‐hand stabilizer by a drum, cables and idler pulleys. Rotating the sprocket changes the
effective length of the actuator assembly, and positions the trim tab by means of a pushrod in the elevator. Trim
tab level is limited by stops as either end of the trim tab wheel travel. An electric elevator trim system is available
as an optional system.
RUDDER CONTROL SYSTEM (Figure 7‐4)
The rudder is attached to the vertical stabilizer fin rear spar at three points. The rudder is actuated by a horn
bellcrank attached to the bottom of the rudder torque tube. The bellcrank is actuated by cables attached to idler
bellcranks forward of the control column. The idler bellcranks are connected to the rudder pedals by pushrods.
RUDDER TRIM SYSTEM (Figure 7‐5)
The rudder trim tab is a bonded structure composed of ribs, spars, and skin. The trim tab forms the lower portion
of the rudder trailing edge, and is connected to the rudder with a piano‐type hinge. A horn assembly extending
from the left‐hand side of the trim is connected to the control system by an adjustable pushrod extending through
the rudder structure.
As the rudder trim tab control wheel is rotated, its angular displacement is transmitted to a chain and sprocket
located within the vertical stabilizer by a drum, cables, and idler pulleys. Rotating the sprocket changes the
effective length of the actuator assembly, and positions the trim tab by means of a pushrod in the rudder. Trim
tab travel is limited by stops at either end of the trim tab wheel travel.
WING FLAP SYSTEM
The flap system consists of a flap mounted on each wing, a worm gear actuator, reversible DC motor, torque tube,
and mechanical linkage. The electrical motor, located beneath the rear passenger seat, turns a worm drive gear in
the gearbox. The worm gear turns a screw mechanism which moves the push‐pull linkage. The linkage is
connected to a horn on the flap torque tube. A bellcrank at each end of the torque tube transmits the movement
through pushrods to the flaps (see Figure 7‐6). Flap travel is limited beyond 0° and 30° by a pair of cam operated
microswitches. A cam on the torque tube also operates a position indicator transmitter.
Flap operation is controlled through the range of 0° to 30° by means of a three‐position flap switch located on the
instrument panel to the right of the center console. A flap position indicator is located adjacent to the switch. The
flap switch is spring loaded from the down position back to the neutral position. The switch must be held down
until the position indicator shows the desired flap travel; when released, it returns to neutral and flap travel stops.
When the switch is moved to the up position it will hold in position until turned off or the flaps contact the 0° (up)
microswitch.
