Since the pressure of airflow that normally opposes movement of
control surfaces is absent during preflight check, it is possible to get
a hard over control surface deflection if an autopilot command is
allowed to remain active for any appreciable length of time. Move
turn knob and pitch thumbwheel only enough to check operation,
then return them to the center position.
4. Select HDG mode - Check.
5. Horizontal situation indicator (HSI) heading marker under lubber line -
6. Engage autopilot and check controls stiff and AIL HI TORQUE, HDG, and
AP ENG are illuminated - Check.
7. Move HSI heading marker 100 left and right and verify that FD and
control wheels respond in the appropriate direction - Check.
8. Press AP/YD disengage switch and verify that autopilot disengages and
that flight controls are free -Check.
9. Engage autopilot - Check.
10. Command 50 trim UP with AP pitch wheel and verify that manual trim
wheel moves nose UP and AP trim light indicates UP trim - Check.
11. Press pitch trim switch nose down and verify that autopilot disengages
and AUTOPILOT TRIM FAIL and MASTER WARNING lights illuminate -