Narrative:

During passenger boarding in ZZZ, we got a pitch trim fail caution light, autotrim fail on both pfd's (primary flight display), full nose up pitch indication, and no trim available. Air carrier maintenance control said there was a service letter that called for pulling the pitch trim circuit breaker, resetting, and then running the trim full deflection on both directions. This failed to restore any of the symptoms, so we were unable to move the trim. He then said to power the aircraft down, and this did clear the faults. He asked if I was comfortable with that, and I said no, that we had cleared the fault, but done nothing to fix the problem. It would probably happen again, and quite possibly in the air next time. He asked if I would be happier if they got a mechanic out to check the fault codes, and I said yes. He called back 10 mins later to say no mechanic was available, but that the manufacturer representative had said just to run it. We did this for just a few mins and the problem did not reoccur. He then had me sign off the discrepancy per a service letter. We then flew to ZZZ1 uneventfully. On the ZZZ1-ZZZ2 flight, we once again got the pitch trim fail caution, autotrim fail messages on both pfd's, full nose up trim indication, and complete loss of pitch trim control. We ran the checklist and landed uneventfully. The failure occurred descending through about 3000 ft, clean, about 230 KTS and while the trim button was not being used. The autoplt was on at the time of the failure. Callback conversation with reporter revealed the following information: the reporter stated maintenance did not release any details on the pitch trim fix. The reporter said on arrival, the airplane was removed from service and the crew was put on another airplane and dispatched.

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Original NASA ASRS Text

Title: A DHC8-400 HAD COMPLETE LOSS OF PITCH TRIM CTL ON GND. CLRED WITH SVC LETTER ACTION. SECOND LEG IN AIR AT 3000 FT, LOST PITCH CTL AGAIN. CAUSE UNKNOWN.

Narrative: DURING PAX BOARDING IN ZZZ, WE GOT A PITCH TRIM FAIL CAUTION LIGHT, AUTOTRIM FAIL ON BOTH PFD'S (PRIMARY FLT DISPLAY), FULL NOSE UP PITCH INDICATION, AND NO TRIM AVAILABLE. ACR MAINT CTL SAID THERE WAS A SVC LETTER THAT CALLED FOR PULLING THE PITCH TRIM CIRCUIT BREAKER, RESETTING, AND THEN RUNNING THE TRIM FULL DEFLECTION ON BOTH DIRECTIONS. THIS FAILED TO RESTORE ANY OF THE SYMPTOMS, SO WE WERE UNABLE TO MOVE THE TRIM. HE THEN SAID TO PWR THE ACFT DOWN, AND THIS DID CLR THE FAULTS. HE ASKED IF I WAS COMFORTABLE WITH THAT, AND I SAID NO, THAT WE HAD CLRED THE FAULT, BUT DONE NOTHING TO FIX THE PROB. IT WOULD PROBABLY HAPPEN AGAIN, AND QUITE POSSIBLY IN THE AIR NEXT TIME. HE ASKED IF I WOULD BE HAPPIER IF THEY GOT A MECH OUT TO CHK THE FAULT CODES, AND I SAID YES. HE CALLED BACK 10 MINS LATER TO SAY NO MECH WAS AVAILABLE, BUT THAT THE MANUFACTURER REPRESENTATIVE HAD SAID JUST TO RUN IT. WE DID THIS FOR JUST A FEW MINS AND THE PROB DID NOT REOCCUR. HE THEN HAD ME SIGN OFF THE DISCREPANCY PER A SVC LETTER. WE THEN FLEW TO ZZZ1 UNEVENTFULLY. ON THE ZZZ1-ZZZ2 FLT, WE ONCE AGAIN GOT THE PITCH TRIM FAIL CAUTION, AUTOTRIM FAIL MESSAGES ON BOTH PFD'S, FULL NOSE UP TRIM INDICATION, AND COMPLETE LOSS OF PITCH TRIM CTL. WE RAN THE CHKLIST AND LANDED UNEVENTFULLY. THE FAILURE OCCURRED DSNDING THROUGH ABOUT 3000 FT, CLEAN, ABOUT 230 KTS AND WHILE THE TRIM BUTTON WAS NOT BEING USED. THE AUTOPLT WAS ON AT THE TIME OF THE FAILURE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED MAINT DID NOT RELEASE ANY DETAILS ON THE PITCH TRIM FIX. THE RPTR SAID ON ARR, THE AIRPLANE WAS REMOVED FROM SVC AND THE CREW WAS PUT ON ANOTHER AIRPLANE AND DISPATCHED.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.