Garmin G1000 Pilot’s Guide for the Socata TBM 850/900
190-00709-05 Rev. D
546
AUTOMATIC FLIGHT CONTROL SYSTEM
7.8 ABNORMAL OPERATION
SUSPECTED AUTOPILOT MALFUNCTION
NOTE:
Consult the aircraft documentation for the location of circuit breakers as well as specifics that may
supplement or amplify this procedure.
If an autopilot failure or trim failure is suspected to have occurred, perform the following steps:
1)
Firmly grasp the control wheel.
2)
Press and hold the
AP DISC
Switch. The autopilot will disconnect and power is removed from the trim motor.
Power is also removed from all primary servo motors and engaged solenoids. Note the visual and aural alerting
indicating autopilot disconnect.
3)
Retrim the aircraft as needed. Substantial trim adjustment may be needed.
4)
Pull the appropriate circuit breaker(s) to electrically isolate the servo and solenoid components.
5)
Release the
AP DISC
Switch.
OVERPOWERING AUTOPILOT SERVOS
In the context of this discussion, “overpowering” refers to any pressure or force applied to the pitch controls
when the autopilot is engaged. A small amount of pressure or force on the pitch controls can cause the autopilot
automatic trim to run to an out-of-trim condition. Therefore, any application of pressure or force to the
controls should be avoided when the autopilot is engaged.
Overpowering the autopilot during flight will cause the autopilot’s automatic trim to run, resulting in an out-
of-trim condition or cause the trim to hit the stop if the action is prolonged. In this case, larger than anticipated
control forces are required after the autopilot is disengaged.
The following steps should be added to the preflight check:
1)
Check for proper autopilot operation and ensure the autopilot can be overpowered.
2)
Note the forces required to overpower the autopilot servo clutches.
