What was found
(CAN) AT SPRING RUN UP, ENG SOUNDS LIKE TWIN ENG ACFT WITH PROPS OUT OF SYNC. CAM RING EXHAUST TRACK WEAR SUSPECTED AS IS A KNOWN PROBLEM WITH THIS INDICATION. CAM INSPECTED & WEAR FOUND ON 3 OF 4 CAM LOBES OF EXHAUST TRACK. CAM PN 11768 & 9 EXTRACK ROLLERS PN 599 REPLACED WITH SERVICEABLE UNITS. ENG GND RUNS COMPLIED WITH OIL SCREENS, FOUND CLEAR & LEAK CHECKS CARRIED OUT. ENG & ACFT RETURNED TO SERVICE.