Flight Control System Operation Electrical
TTP
|
B1-----
|
ATA27A
|
Cessna
172
|
B2-L3
|
Flap-
control system has an electric motor and
transmission assembly, drive pulleys, push-pull rods, cables, and a follow-up
control. Power from the motor and the transmission assembly goes to the flaps
by a system of drive pulleys, cables, and push-pull rods.
Electrical power to
the motor is controlled by two MSW mounted on a floating arm assembly,
a cam lever, and a follow-up control. As the flap control lever moves to the
necessary flap setting, the attached cam activates one of the microswitches, and that activates the flap motor.
As the flaps move to the necessary position, the floating arm is turned by the
follow-up control until the active microswitch clears the cam. The circuit breaks
and the motor stops.
To move the flap in the opposite direction, the control
lever is moved in the opposite direction. This causes the cam to activate the
second microswitch, which changes the direction of the flap motor. The
follow-up control moves the cam until it is clear of the second switch, which
stops the flap motor. Limit switches at the flap actuator assembly control flap
travel as the flaps get to the full UP or DOWN position.
Flap follow up and
indicating system consists of a sheathed cable assembly, pointers and micro switches.
One end of the cable is attached to the flap operating switch operating arm.
The other end is clamped to the flap direct cable, above the headliner in the
rear cabin area. Motion of the flap cable is transmitted through the follow up
control to the pointer, attached to the switch mounting arm.
Pointer moves
along a scale as the flaps are extended or retracted. When the motion of the
switch mounting arm with the attached operating switches positions the
"active" operating switch to clear the cam on flap lever, flap
motor circuit is broken and flaps stop at selected position.
Trim system - elevator trim tab on the right elevator is
controlled by a trim wheel in the pedestal. Movement to operate the tab goes from
the trim control wheel with chains, cables, and an actuator. A mechanical pointer
adjacent to the trim wheel shows the tab position. A nose up setting on the
trim wheel gives a tab down position.
PTP
Cessna
172
|
B1
|
LOC
|
FOT
|
SGH
|
R/I
|
MEL
|
|
B2
|
LOC
|
FOT
|
R/I
|
TS
|
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