What was found
MACH TRIM FAIL LIGHT ILLUMINATES WITH MASTER CAUTION RECALL AND EXTINGUISHES WHEN MASTER CAUTION IS RESET. ACFT GROUNDED. PERFORMED FIM 22-11 TASK 801, FAULT HISTORY SHOWED FCC-A MACH TRIM 28 VDC FAULT LAST FLIGHT. CURRENT STATUS TEST FAILS MACH TRIM ON A CHANNEL, PASSED ON B CHANNEL. REMOVED MAINTENANCE PROCEDURES, TWO CIRCUIT BREAKERS RESET, COLLARS REMOVED. ACFT CONFIGURATION RETURNED TO NORMAL. PERFORMED FIM 22-11 TASK 801, CURRENT STATUS, MACH TRIM BITES 13.33 AND 60.33. TESTS OPS NORMAL NUMEROUS TIMES. NO HISTORY LAST 90 DAYS PLUS.