What was found
LT AND RT MAGNETOS EXPERIENCING REPEATED INTERNAL TIMING DRIFT DURING SHORT PERIODS OF OPERATION. ACFT ARE ON A 50 HOUR PHASE INSPECTION CYCLE. PILOTS REPORT DIFFICULTY STARTING ACFT, INSP RESULTS DETERMINE THAT MAGNETOS ARE CAUSE. REMOVAL OF MAGNETOS, DISASSEMBLY AND INSP REVEAL THAT THE INTERNAL TIMING HAS DRIFTED TO THE EARLY SIDE OF THE E-GAP POSITION, INSPECTION OF THE CAM SHOWS NO WEAR, POINTS BREAKER ASSY SECURE, LITTLE OR NO PITTING ON THE CONTACTS. INITIALLY, CONTACTS WERE REPLACED, THEN 50 HOURS LATER HARD TO START. MAGS REMOVED, INTERNAL TIMING 6 DEGREES EARLY. INTERNAL TIMING RESET, CONTACTS NOT REPLACED. MAGS REINSTALLED AND TIMED TO ENGINE 20 DEG BTDC AS REQUIRED. 50 HOURS LATER HARD TO START, INTERNAL TIMING FOUR DEGREES EARLY, INTERNAL TIMING RESET, CONTACTS NOT REPLACED. THIS PROBLEM NOT SPECIFIC TO THIS LOCALE.