What was found
MACH TRIM FAIL LIGHT ON RECALL, VERY CHRONIC. AFTER TROUBLESHOOTING & PARTS REPLACEMENT, REVIEW OF BITE DATA REVEALED INTERMITTENT MOMENTARY LOSS OF POWER TO MACH TRIM SYS. CIRCUIT BREAKER C1064, B-MACH TRIM DC, REPLACED & TEST FLT PERFORMED. INTERMITTENT NATURE OF FAILURE DUE TO IMPROPER SEQUENCING OF RESET OF CB & OTHERS, BY MX AFTER LONG LAY-OVERS, RESULTED IN FAILURE OF FCC TO POWER-UP IN TIME FOR MACH TRIM TEST. WHEN CREW PERFORMED MASTER CAUTION RECALL, MACH TRIM LIGHT ILLUMINATED INDICATING A SINGLE CHANNEL FAULT. AIRCRAFT HAS ACCUMULATED 71 FLT HRS WITHOUT A REOCCURENCE SINCE BREAKER REPLACED.