Power loss leads to rough autorotation

 - May 6, 2008, 12:03 PM

ENSTROM F-28C, NEAR MEDICINE BOW, WYO., JUNE 10, 2002–N5694Z, operated by Falcon Helicopter and piloted by a commercial-rated pilot, was substantially damaged during a hard landing at 9:45 a.m. near Medicine Bow. The pilot sustained serious injuries, and the passenger received only minor injuries. The weather was reported to be VMC for the flight, which originated in Laramie, Wyo., at 7:30 a.m. on a pipeline-patrol mission.

At the time of the accident, the pilot said he was marking the positions of two pipeline valves using GPS. He said they missed the second valve and turned around to go back and mark the location. After marking the location, the pilot said he then turned around again to go back to his original course following the pipeline.

As he was completing the turn and pulling power, he experienced an engine power drop off. The pilot said he was about 100 ft agl when he experienced the problem. He immediately reported that he was executing an autorotation, which resulted in the rotorcraft crashing into the ground. The helicopter came to rest upright in an open field.

A preliminary examination of the helicopter showed that the left skid was broken upward and the bottom of the fuselage was crushed upward. The tailboom was separated aft of the baggage compartment. The forward windscreen and chin windows were broken out.

The trailing edges of two of the three main rotor blades were bent downward, wrinkled, torn and twisted. The tail-rotor gearbox was found resting on the ground in front of the helicopter. The tail-rotor blades were bent outward, and the engine was retained for further examination.