Accident Overview
While on radar vectors for an Instrument Landing System (ILS) approach in instrument meteorological conditions (IMC), the pilot experienced a total loss of engine power. The aircraft subsequently descended through clouds and fog, ultimately colliding with trees in an orchard.
Pilot Report
The pilot reported that the low voltage annunciator light illuminated, followed by a drop in oil pressure to zero and engine seizure.
Engine Examination
Post-accident examination of the engine revealed damage consistent with oil starvation. The bearings and connecting rods had failed due to lack of lubrication. The oil pump drive gear was found separated from its shaft and loose within the accessory gear case.
Metallurgical Findings
A metallurgical examination of the oil pump drive gear identified rough machining marks located around the fillet radius between the longitudinal shaft and the web portions of the gear.
Conclusion
The investigation determined the engine failure was caused by oil starvation resulting from the separation of the oil pump drive gear from its shaft.