What was found
APPROXIMATELY 5 MINUTES AFTER TAKEOFF, LT ENGINE OIL PRESSURE INDICATION DECREASED TO ZERO, THEN BELOW ZERO WITHIN 2 MINUTES. SINCE OIL TEMP WAS STILL INCREASING AFTER DEPARTURE, NO RELIABLE MEANS OF DETERMINING ENGINE OIL CONDITION WAS AVAILABLE. ENGINE WAS SHUT DOWN IN-FLIGHT TO PRECLUDE POSSIBLE DAMAGE. DIAGNOSIS OF 3 IN 1 INSTRUMENT REVEALED THE OIL PRESSURE NEEDLE WAS LOOSE ON SHAFT.