[Username Protected]

We need some help. My Phenom 100, serial 53, completed its routine annual maintenance last week. Unfortunately, sometime during the maintenance, the aircraft developed a normal pitch trim failure (PTRIM NML FAIL). The aircraft, over 13 years and 1,500 hours, has never had a pitch trim failure until now. Over the last week, we've done everything possible to isolate the problem, including:

• Swapped Trim Actuator Controllers 1 and 2.
• Replaced LH Trim Actuator
• Swapped GIA 1 and GIA 2
• Ruled out Pilot and Copilot Switches - wiring checks good
• Ruled out Autopilot Disconnect Switches- wiring checks good
• Ruled out CWS switches- wiring checks good
• Rang out wiring from TAC 1 and TAC 2 to Actuator
• Rang out wiring from GIA 1 and GIA 2 to TAC 1 and TAC 2

No success.

In addition to the normal pitch trim hard failure, we are also getting a new CAS message never before seen: PRESN AUTO FAIL. This happens immediately on power-up. Flipping the PRESN MODE switch to Manual and then back to Auto as per the QRH fixes the problem. This seems unlikely to be related to the trim problem, but who knows?

Any suggestions for fixing this stubborn Gremlin would be appreciated. Thanks.

[Username Protected]

(Username Protected), due to the age of the plane and the likelihood the TAC’s have been swapped before, I’d reccommend ordering/replacing the controllers.

[Username Protected]

(Username Protected),

I had an issue that would come and go, but when it appeared it was either on climb through about 190-210 or on descent through 170-180. They replaced everything on the aircraft related to the pitch trim and still it persisted. It ended up being a problem with pins in a circular (38999 style) bulkhead connector. When the airplane would cool off in the climb or warm up in the descent, the connection would be lost briefly creating the error. Once it detects a signal loss, however brief, you can only reset it with a power cycle.

Your issue does not sound like this, although I do have an older aircraft (s/n 29), it still might be a clue. The pattern was elusive. The fact that you have replaced everything, may point to another system related issue similar to mine. After it was all over, the pattern of the failure in climb and descent made sense, but at the time it was not clear as there were a couple of failures that did not fit the pattern.

Good luck!

[Username Protected]

We found the problem causing PTRIM NML FAIL. It was a software configuration issue after the FMS unit had been replaced. The FMS replacement required a partial software reinstall. Somehow, the software install resulted in the GFC configuration on GIA 1 for the pitch trim servo being incorrectly set to NONE while the GIA 2 was correctly set to EMB500 TRIM. Changing the GIA 1 setting to EMB500 TRIM fixed the pitch trim problem.

And why did we replace the FMS unit which had worked perfectly for 13 years? Because the five dollar range knob was broken and Garmin does not allow the knob alone to be replaced -- the entire FMS must be replaced.

[Username Protected]

(Username Protected), Anytime we've had a Garmin part replaced on this aircraft or prior, if the software doesn't get installed exactly in the proper order and every option being correctly indicated, the system throws a fit and spits out CAS messages randomly. I love Garmin products, but their weak link is the quality of the hardware: switches, cables, cannon plugs....

[Username Protected]

And as everyone on this forum seems to find out, any time you reinstall the G1000 software, check to ensure the CMC download tool is also installed, because many service centers forget to install it. (It's not on the maintenance procedure for reinstalling G1000 software.). I've added that to my acceptance checklist - just check to make sure I can do a CMC download successfully.