What was found
(CAN) AFTER TAKEOFF, THE PILOT LOST OIL PRESSURE INDICATION, HOWEVER, THERE WAS NO MASTER CAUTION INDICATION. THE PILOT RETURNED TO BASE WITHOUT INCIDENT. INVESTIGATION REVEALED THAT THE WIRE HARNESS, BETWEEN THE OIL PRESSURE TRANSMITTER AND THE FIREWALL CONNECTOR PLUG WAS CHAFED THROUGH APPROX.12 INCHES FROM THE FIREWALL END, IN THE AREA WHERE THE COOLING DUCT FOR THE STARTER GEN PASSES OVER THE WIRE HARNESS. THE WIRE HARNESS WAS REPLACED AND THE OIL PRESSURE INDICATING SYSTEM FUNCTIONED NORMALLY.