Engine Failure and Ditching
Approximately 45 miles from landing, the left engine's revolutions per minute (RPM) began to fluctuate. When the aircraft was about 15 miles from landing, the engine lost power completely. The pilot reported that the aircraft could not maintain altitude. Unable to reach the runway, he ditched the aircraft in Hilo Bay, approximately one-quarter mile from shore and 1.5 miles from the airport.
Post-Recovery Examination
After the aircraft was retrieved, the airframe and left engine were examined. The accessory gear drive shaft was found to have failed in torsional overload. Inside the accessory gear case, an area of gouging and abrasion was located directly in front of the starter gear. The left magneto, fuel pump, and propeller governor were driven by the accessory drive gear.
Deep impressions were noted on approximately 70% of the gear teeth, with material displacement and gouging evident. There was evidence that the collector drive floating gear may have moved forward and contacted the engine case. Additionally, there was evidence of mechanical interference within the accessory drive gear system.
Weight at Time of Accident
The aircraft's gross weight at the time of the accident was about 9,108 pounds.