Accident Overview
On August 11, 2014, at approximately 1130 Pacific daylight time, a Hughes 269C helicopter, registration N7432F, collided with terrain near Darrington, Washington, following a partial loss of engine power. The airline transport pilot sustained no injuries, and the helicopter incurred substantial damage. The flight was operated by Snohomish Flying Service (SFS) under 14 Code of Federal Regulations Part 91 as a local personal flight. The helicopter had departed Snohomish, Washington, around 0815. Visual meteorological conditions prevailed, and no flight plan was filed.
Flight Narrative
The pilot reported that during the flight, while descending from 5,000 feet, he increased collective pitch as the helicopter approached 4,000 feet. The engine began to slow down, and the pilot was unable to restore the engine rpm to a normal range. The helicopter continued descending until the pilot initiated an autorotation. During the descent, the helicopter struck a tree approximately 30 feet high and subsequently came to rest in a small stream. The pilot stated that he did not believe the engine had completely stopped, but it was not producing sufficient power to sustain flight.
Examination Findings
On August 12, 2014, the helicopter was recovered by SFS and examined by Federal Aviation Administration inspectors with assistance from SFS personnel. The examination revealed that the throttle mount bracket was hanging by the throttle cable linkage and was not secured to the servo mount studs as intended. This condition would prevent the loss of throttle movement for acceleration. The operator stated that the engine had been installed in the helicopter just 10 flight hours prior to the accident.