I wanted to share the solution in case it helps someone else troubleshoot a similar issue.
Aircraft
Symptoms
Root Cause
The problem was not the trim servo or the Garmin system.
The culprit was the 6-pin plastic connector at the Ray Allen trim servo in the tailcone. The female terminals inside the connector had lost their spring tension and had enlarged over time. Although the connector looked perfectly normal externally, the loose female contacts created intermittent electrical connections. Engine vibration would occasionally cause the circuit to open, disabling both the trim motor and the trim position feedback.
Fix
I replaced the original 6-pin plastic connector with a locking metal D-sub (DB9-style) connector using new crimp contacts.
The locking screws eliminate the possibility of connector movement, and the new contacts provide a much more reliable electrical connection.
Lesson Learned
If your RV-12 electric trim operates intermittently, especially if the trim position indicator also freezes or stops updating, inspect the Ray Allen trim servo connector in the tailcone before replacing the trim servo or troubleshooting the Garmin avionics.
The connector may appear perfectly normal from the outside while the female terminals inside have lost enough contact tension to cause intermittent failures.
Hopefully this saves someone else a lot of troubleshooting time.
Regards,
Amit
Aircraft
- 2021 RV-12iS (ELSA)
- Garmin G3X Touch
- 217 hours total time
- Ray Allen Trim servo
Symptoms
- Electric pitch trim would randomly stop working in flight.
- The trim position indicator on the G3X would also stop moving (but blinked in place) whenever the trim stopped working.
- Initially it appeared to be related to higher RPM or vibration, making it difficult to diagnose.
- The trim would later begin working again without any obvious reason.
- Garmin configuration tests and the trim servo itself appeared to be normal on ground.
Root Cause
The problem was not the trim servo or the Garmin system.
The culprit was the 6-pin plastic connector at the Ray Allen trim servo in the tailcone. The female terminals inside the connector had lost their spring tension and had enlarged over time. Although the connector looked perfectly normal externally, the loose female contacts created intermittent electrical connections. Engine vibration would occasionally cause the circuit to open, disabling both the trim motor and the trim position feedback.
Fix
I replaced the original 6-pin plastic connector with a locking metal D-sub (DB9-style) connector using new crimp contacts.
The locking screws eliminate the possibility of connector movement, and the new contacts provide a much more reliable electrical connection.
Lesson Learned
If your RV-12 electric trim operates intermittently, especially if the trim position indicator also freezes or stops updating, inspect the Ray Allen trim servo connector in the tailcone before replacing the trim servo or troubleshooting the Garmin avionics.
The connector may appear perfectly normal from the outside while the female terminals inside have lost enough contact tension to cause intermittent failures.
Hopefully this saves someone else a lot of troubleshooting time.
Regards,
Amit
