What was found
INVESTIGATED IN-FLIGHT "AP PITCH TRIM FAIL" ANNUNCIATOR INDICATION. VERIFIED AUTOPILOT NOSE UP PITCH TRIM FUNCTION INOPERATIVE. SWAPPED NR 1 AND NR 2 FCC-4007 CARDS FOR TROUBLESHOOTING, NO FAULTS INDICATED. AUTOPILOT NOSE-UP TRIM CONTROLLED BY NR 2 FCC-4007 CARD. IAW MX CONTROL, ACFT HAD PRIOR OCCURENCE OF LOSS OF AUTOPILOT NOSE-UP PITCH TRIM CONTROL. SUBJECTED SUSPECTED NR 2 FCC-4007 COMPUTER TO ENVIRONMENTAL COLD CHAMBER CONDITIONS, NO FAULTS INDICATED. REPLACED NR 2 FCC-4007 COMPUTER WITH AN O/H FCC-4007 COMPUTER, NO FAULTS INDICATED, AUTOPILOT PITCH TRIM FUNCTIONS NORMAL. RECOMMEND FLIGHT CONTROL COMPUTER MFR INVESTIGATE SUSPECTED FCC-4007 COMPUTER AT INCOMING INSPECTION TO DETERMINE SOURCE OF FAILURE INDICATIONS.