What was found
CAPTAIN REPORTED THAT OIL PRESS DURING TAKEOFF & CLIMB RAISING TO 70 PSI, FLASHING INDICATION CRUISE "FT 58 PS’S" REDUCING POWER. CAPTAIN REPORTED STRONG VIBRATION IN THE PAX CABIN. RT ENGINE OIL PRESS ADJUSTED IAW MM, TESTED CORRECT & ENGINE VIBRATION CHECK PERFORMED IAW MM. LATER, ACFT RETURNED TO PLATFORM 2 TIMES DUE TO SAME FAILURE. OIL PRESS TRANSMITTER REPLACED AND RT ENGINE OIL PRESS ADJUSTED IAW MM 79-20-03, TESTED CORRECT. DURING OVERNIGHT SERVICE, CSD, OIL GENERATOR & RADIATOR WERE REPLACED IAW MM, RT ENGINE MAIN OIL FILTER & CHIP DETECTORS WERE CHECKED IAW MM. RT ENGINE OIL PRESSURE VALVE REPLACED IAW MM, TESTED CORRECT.