What was found
(CAN) DURING MEDEVAC MISSION MASTER CAUTION LIGHT AND XMSN PRESSURE LIGHT ILLUMINATED. THE PRESSURE GAUGE WAS DROPPING RAPIDLY. PRESSURE THEN DROPPED TO ZERO. FLIGHT CREW MADE A PAN PAN CALL TO NEAREST ATC AND EXECUTED EMERGENCY LANDING WITHOUT FURTHER INCIDENT. UPON INSP BY MX IT HAS BEEN DETERMINED THAT LOSS OF TRANSMISSION OIL WAS DUE TO SEPARATION OF OIL JET FROM THE LOWER HSG OF MAIN TRANSMISSION . THE OIL JET WAS HELD BY A RETAINING RING IN A SLEEVE INSERTED INTO THE LWR HSG (SLEEVE INSERT) - THE SLEEVE SEPARATED FROM THE HSG. MGB COWLING PREVENTED THE OIL JET FROM ACTUALLY BREAKING FREE FROM THE MGB. MGB TSO=419.4 HRS, OIL JET PN 76351-09105.