Raytheon Aircraft Company A36 N464TJ accident near Lopez Island, Washington

Probable cause

A loss of engine power during cruise flight due to oil starvation. The oil starvation event was due to the failure of maintenance personnel to tighten the aft mounting nuts for the newly installed propeller governor and the pilot’s failure to secure the oil filler cap during the preflight inspection.

NTSB analysis

The pilot reported that during cruise flight, the propeller rpm continued increasing despite his numerous attempts to reduce the propeller rpm. As the pilot reduced power, he heard a loud bang followed by a "significant trail of white smoke pouring over the wind screen" and a loss of engine power. The pilot initiated a forced landing to a nearby road that appeared to have no vehicle traffic. The pilot stated that he extended his approach to landing due to a vehicle turning onto the road. During the landing roll, the left wing struck a street sign and subsequently struck "two or three large wooden fence posts that were hidden in the bramble of blackberry bushes” that resulted in structural damage to the empennage and the left and right wings. Examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed that the oil filler cap was unsecured to the oil filler neck. Oil residue was observed along the left side of the airframe and engine cowling. Further examination of the engine revealed that the two aft nuts securing the propeller governor to the crankcase mounting pad were loose. Oil residue was observed within the surrounding area of the propeller governor. About 1 quart of oil was observed within the oil sump. Review of maintenance logbooks revealed that the engine was recently disassembled and inspected due to a propeller strike. Following the propeller strike inspection, the propeller governor was reinstalled. The pilot reported that the accident flight was the first flight following the propeller strike inspection and that he verified the oil level was adequate during his preflight inspection.

Text from the NTSB. Open the NTSB docket for WPR09LA197 for the full record.