What was found
DURING CLIMB THROUGH FL310, THE LEFT ENGINE OIL PRESSURE DROPPING STEADILY, FOLLOWED BY A LOW OIL PRESSURE LIGHT AND MASTER WARNING. THE ENGINE WAS SHUT DOWN AND AN UNEVENTFULL LANDING WAS MADE. UPON INSPECTION, OIL APPEARED TO BE LEAKING FROM THE ENGINE DIPSTICK TUBE. THIS COULD NOT BE CONFIRMED THROUGH ENGINE GROUND RUN DUE TO LOSS OF OIL AND THE POTENTIAL FOR FURTHER DAMAGE TO THE ENGINE. THE DIPSTICK O-RING HAD BEEN PREVIOUSLY REPLACED DURING A ROUTINE ENGINE INSPECTION AND THE O-RNG APPEARS TOO SMALL FOR THE O-RING GROVE. O-RING EFFECTIVITY CODES LISTED IN THE ENGINE IPC ARE ALL THE SAME, THEY DON'T DIFFERENTIATE BETWEEN THE DIFFERENT DIPSTICKS SHOWN, ADDING CONSIDERABLE CONFUSION TO THE SELECTION PROCESS.