S-TEC System 55X, Operating Handbook

Page: 26 / 56

4-16 2nd Ed: May 31, 2002
SYS FIFTY FIVE X POH
4.2.12 Pitch Trim Indicator
If automatic trim has failed or is turned off, a sensor in the System Fifty
Five X Autopilot pitch servo detects out-of-trim elevator loads. When such
forces exceed a preset level and time delay, TRIM will annunciate on the
Programmer / Computer with either the up or down symbol annunciated
to indicate the direction elevator trim is required. In addition, an audible
warning tone will sound 5 for seconds (this is same audible beeping
tone emitted when the autopilot is disconnected but at a slower rate).
The annunciation will be steady for about 5 seconds, then flash until
proper trim conditions have been met. The pilot will be required to
manually trim the aircraft until the trim indicator is extinguished.
NOTE:
If trim is annunciated and the pilot disengages the
autopilot, there will be residual out of trim force at the
control wheel. Be alert if the autopilot is disengaged
while TRIM is annunciated.
4.2.13 Autotrim
With the autotrim functioning normally, the aircraft elevator trim will be
maintained automatically when the Trim Master switch is on and a pitch
mode is activated.
When the elevator trim is in motion, TRIM and the up or down symbol will
annunciate indicating trim in motion and the direction of travel. Should
the trim continue to run in excess of 7 seconds, these annunciations will
flash.
If the trim master switch is OFF or a failure has occurred in the Autotrim,
the system will automatically revert to "Pitch Trim Indicator" mode of
operation.
NOTE:
Using the trim switch on the control wheel while the
pitch axis of the autopilot is engaged, disconnects
the autopilot.
The pilot is also provided with Manual Electric Trim when the autopilot
is disengaged or if only a roll axis mode has been engaged.