Primary finding
Probable cause
A total loss of engine power due to the separation of a tooth from the starter-generator drive gear, which resulted in failure of the engine oil pump and subsequent oil starvation.
Investigator assessment
Analysis narrative
During cruise flight, the pilot noted a fluctuation in the engine oil pressure followed by the illumination of the red warning light indicating low oil pressure. He performed a precautionary landing, and at 10 feet above ground level, the engine lost total power. The helicopter subsequently landed hard on uneven terrain and rolled onto its left side. Postaccident examination of the engine revealed that a gear tooth on the starter-generator drive gear had separated. The separated tooth jammed the accessory gear drive train, which resulted in the failure of the engine oil pump and subsequent catastrophic engine failure due to oil starvation. The reason for the failure of the gear tooth could not be determined.
Source record
Factual narrative
On September 1, 2011, about 1840 Pacific daylight time, an Arrow Falcon Exporters, Inc., UH-1H helicopter, N205PJ, sustained substantial damage when it rolled over during an emergency landing following a total loss of engine power near Stockton, California. The commercial pilot, the sole occupant, received minor injuries. P.J. Helicopters, Red Bluff, California, was operating the helicopter under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed for the cross-country repositioning flight, which had originated from Tracy, California, about 10 minutes before the accident. A company visual flight rules flight plan was on file and had been activated. The pilot stated that, while in cruise flight, he noted a fluctuation in the engine oil pressure followed by the illumination of the red warning light indicating low oil pressure. As he was performing a precautionary landing, about 10 feet above ground level, the engine had a total loss of power. The helicopter subsequently landed hard on uneven terrain, and rolled onto its left side. Postaccident teardown examination of the engine, which was conducted under the supervision of a Federal Aviation Administration inspector, revealed that a gear tooth on the starter-generator drive gear had separated. The separated tooth jammed the accessory gear drivetrain, which resulted in the failure of the engine oil pump and led to catastrophic engine failure due to oil starvation. The reason for the failure of the gear tooth was not determined.