Hughes Helicopters Inc 369E N427WC accident near The Dalles, Oregon

Probable cause

The loss of engine power due to fuel starvation, which resulted from the fuel tank supply pickup becoming unported while the helicopter was pulling power lines.

NTSB analysis

The operator reported that the helicopter was in an 80-ft hover and had begun lifting and dragging the ends of winch lines used to pull power cables across sloping terrain when the engine lost power. The pilot jettisoned the external load as the helicopter began to descend rapidly. The helicopter's tail boom contacted the ground first and was then cut by the main rotor system, the skids separated from the fuselage, and the helicopter then came to rest on its right side. Several witnesses reported that the engine was still running on the ground after the impact.

Postaccident examination and operational testing of the engine revealed no anomalies that would have precluded normal operation. During previous investigations of similar accidents, it was determined that the fuel tank supply pickup can become unported with a fuel load of less than 151 lbs when pitch-and-roll attitudes approach 20 degrees; the operator reported that about 117 lbs of fuel was recovered from the helicopter. It is likely that the fuel tank supply pickup unported while the helicopter was maneuvering, which led to fuel starvation and the subsequent loss of engine power.

Text from the NTSB. Open the NTSB docket for WPR12LA328 for the full record.