Trio Avionics Pro Pilot - Manual (Page 78)

Trio Pro Pilot Manual 3.8
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Engage the servo by pressing the appropriate H NAV or V NAV switch. You should hear the solenoid
operate inside the servo housing and the servo crank arm should become firmly held in place by the gear
train. Then push the control stick hard enough to override the servo. Using an 11/16 “ or 17mm open
end wrench set the override force to a value that will give good control authority, but not so strong as to
be difficult to override with the control stick.
WARNING
When setting servo force override adjustment on the pitch servo, be aware of the consequence of a pitch
servo disconnect in a moderate to extreme out-of-trim condition. Newer, light aircraft designs can be
extremely pitch sensitive. A servo disconnect while in an out of trim condition could result in an abrupt
change in pitch attitude and in extreme cases it is possible to cause structural damage. In order to
mitigate this risk it is recommended that the clutch be set at a very low force level initially. Flight testing
should then be conducted to determine an appropriate adjustment point for your particular aircraft at the
operational airspeeds. A recommended adjustment scenario is as follows:
1.
Prior to flight, using a spring scale on the control stick, set the clutch force so that a stick
pressure of about 2 lbs results in a clutch slip. On some aircraft it may be necessary to balance the
elevator so that there is no initial load force on the servo. To do this, place the elevator in a flight neutral
position and engage the servo in the ALTITUDE HOLD mode.
2.
Perform a low speed flight test. During this test the aircraft should be placed in a neutral pitch
trim condition and then the servo engaged in the ALTITUDE HOLD mode. While in the ALTITUDE
HOLD mode, the aircraft should be slightly mis-trimmed. While in this condition the autopilot display
should be observed for a CLUTCH SLIP message. If no CLUTCH SLIP message appears after 15
seconds, the pilot should disconnect the servo while maintaining manual pitch control during the release.
3. If
the CLUTCH SLIP message does not appear and the pitch excursion is excessive on release,
then the clutch force should be reduced and the test re-run until the CLUTCH SLIP message occurs at a
point where the aircraft excursion at release is not excessive.
4.
The objective of this test is to have a CLUTCH SLIP message occur at a servo force override
level that will not cause an excessive pitch excursion when the servo is released. Once this setting is
obtained at the low flight speed, testing should be accomplished at progressively higher flight speeds to
ensure a release at any operational airspeed will not result in a significant pitch excursion when the servo
is disconnected with an out-of-trim condition.
Adjustment of Servo Rotation Direction
After installation wiring is complete the system servo direction check must be accomplished. This is a
“one time" setting that must be accomplished while the aircraft is on the ground. Once done, it should
never have to be changed unless you replace a control head, or perform a “default reset” that returns all
settings to the factory defaults.
NOTE: This is a CRITICAL setting and MUST be verified before flight. If the command direction
to the servo motor is not correct the aircraft will be forced into a divergent maneuver when the
system is engaged.
 The
V NAV servo is self centering due to the ability to provide its angular position back to the
control electronics.
 The
H NAV servo will be centered manually in the steps below to facilitate the automatic roll
trim error compensation.
Setting the proper rotation direction of the H NAV and V NAV servos is detailed in the
CONFIGURATION SETTINGS menu, previously described in Chapter 11.