What was found
(CAN) DURING CLIMB, ENGINE LOW OIL PRESSURE LIGHT CAME ON FOLLOWED BY RED MASTER WARNING LIGHT WITH NO OIL PRESSURE INDICATION. PILOT SHUT DOWN ENGINE AND RETURNED BACK TO ORIGIN UNEVENTFULLY.CUSTOMER REPORTED AIRCRAFT BACK IN SERVICE BEING UNABLE TO DUPLICATE ISSUE ON GROUND. DURING CLIMB, ENGINE LOW OIL PRESSURE LIGHT CAME ON FOLLOWED BY RED MASTER WARNING LIGHT WITH NO OIL PRESSURE INDICATION. PILOT SHUT DOWN ENGINE AND RETURNED BACK TO ORIGIN REPORTED AIRCRAFT BACK IN SERVICE BEING UNABLE TO DUPLICATE ISSUE ON GROUND.