Rrhsch
Active Member
Background:
RV12 with Gamin G3X w/GPS20A and Garmin GMC307 w/autopilot.
Trim was used and functioning prior to this flight. This was the first time I used Autopilot with a flight plan. I successfully used direct to with this autopilot prior to this flight.
While using the Garmin auto pilot on flight plan the autopilot brought me down to pattern altitude. I disengaged autopilot and slowed my RV12 for downwind leg and tried to trim for speed but trim didn?t work. Pushed autopilot disengage again to see if autopilot was still engaged. Still didn't work. Landed plane without the use of trim.
Actions:
1.Checked continuity of fuse-good
2. Checked wires on servo connection. Everything looked good.
3. Used external power source and moved servo in both directions.
4. Moved p trim screw 20 turns CCW and retested trim button.
5. Removed WH-00046 Fuselage harness and externally powered pins 31 and 32 with servo movement in + and - orientation. Replaced cable.
6. Removed switch harness cable. Removed pins 18 and 19 and reconnected harness. Put each pin to ground one at a time. No servo movement.
7. Repeated above with Autopilot on. Same result.
8. Turned Autopilot off and measured voltage to each pin (18 and 19) to ground. Each measured 4.8V each.
Conclusion:
I am able to make the servo function using external power source through the Fuselage harness. Pins 18 or 19 to ground do not cause the servo to move. I believe this simulates the same function as the trim switch. Please correct me if I am wrong. Assuming that this is correct the only part left to make the trim work is the AV-5000A logic box. Everything seems to function to and from the AV-5000A. I believe I have a bad AV-5000A.
Have I missed something?