ANC93LA125

While hovering with just the toes of the skids against the approximate 45 degree side of the mountain, a load thump was heard and felt by the pilot and passenger and the helicopter settled backwards with the tail coming to rest on the ground. The pilot said he experienced a partial loss of engine power and could not maintain the hover. The engine later operated normally on a test stand. The cause of the power loss was not determined.

History of flight

On July 23, 1993, at 2045 Alaska daylight time, a skid equipped Hughes 369D helicopter, N3115Y, operated by Soloy Helicopters, Inc. of Wasilla, Alaska, experienced a hard forced landing following a partial loss of engine power while hovering over steep terrain approximately 28 miles east of Cordova, Alaska. The airline transport pilot, one passenger, and one person on the ground beside the helicopter were not injured. The helicopter sustained substantial damage. The unscheduled domestic passenger/cargo flight, operating under 14 CFR Part 135, departed its base camp located about 15 miles to the southwest at 2030. Visual meteorological conditions existed, and a company VFR flight plan was filed.

During a telephone conversation shortly after the accident the pilot stated the following, in part: "I was hovering with only the toes of the helicopter skids on the approximate 45 degree slope. The wind was calm, and the elevation was 700 feet above sea level. I was planning to land to pickup 2 passengers and some equipment to take to another location. One passenger had got in and fastened his seat belt, and the second person was handing cargo to the him and preparing to get in. I heard and felt a loud thump and the helicopter slowly settled backward to the ground. I kept increasing collective but the engine had lost power to where I could not maintain the hover. When the helicopter settled backward on the mountainside, the tail rotor blades hit the ground, the lower vertical stabilizer went into the ground, and the tail rotor driveshaft sheared. The engine was still running at about 70 percent N1. I shut the engine down and we got out very carefully. This was a newly cut landing area, and I had not landed there previously."

The passenger stated that he heard and felt a loud thump just before the helicopter settled backwards. However, the person on the ground, about 4 feet from the helicopter, said he did not hear any unusual noise.

Tests and research

Shortly after the accident, the engine was removed from N3115Y and taken to the Soloy Helicopters maintenance facility in Wasilla, Alaska. On August 3, 1993, a thorough examination was made of the engine under the supervision of FAA Inspector Richard L. Mason, FSDO (Flight Standards District Office), Anchorage, Alaska. A pneumatic systems check was performed during which a loose "B" nut was found on the governor. It was not determined if this nut had been loosened during the engines removal from the helicopter.

The engine was taken to its manufacturer, Allison Gas Power Turbines, 2355 South Tibbs, Indianapolis, IN 46241-3644, for further examination and tests. An Allison official, Mr. Jeff Edwards, stated that the engine the Flight Standards District Office in Indianapolis.

On September 15, 1993, the engines fuel pump was tested and found to be operational at NAC, 7200 Lockheed, Oakland, CA 94621. (Work Order # RAOOOO 1540).

On September 17, 1993, the engines governor and fuel control were tested, and no anomalies found, at Allied Signal, Inc., 117 East Providencia Avenue, Burbank, CA 91502. (Work Order #s 23007506 and 23056935)

Additional information

Approximately 30 minutes before the accident, N3115Y had refueled at the company's base camp. No problems were found with the fuel or refueling system. No fuel or system problems were reported by any of the several other flightcrews using fuel from the same source.

Following the accident, Soloy Helicopters President Chris Soloy stated that the results were negative from the pilot's post accident toxicological tests.