ASN Wikibase Occurrence # 285005
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Narrative:According to the pilots, the helicopter was at an altitude between 400 and 500 feet above ground level and at an airspeed between 75 and 80 knots when the engine lost power. The instructor-pilot took control of the helicopter, jettisoned the external load, and autorotated to a nearby corn field. He said that the engine "didn't sound like it was running and the engine out was activated." The helicopter touched down and slid 6 to 8 feet when one of the skids dug into the earth. The helicopter turned to the left about 45 degrees and rolled over on its right side. It was later found that the power turbine governor (PTG) spring had fractured in fatigue. The fracture originated from a drawing mark and was the result of deficiencies in the manufacturing process. The PTG spring "provides force opposing those exerted by rotating flyweights on the position of the governor lever. Failure of the spring would result in a false pneumatic signal to the fuel control and a corresponding reduction in fuel flow. The effect of the false pneumatic signal would be a pronounced reduction in fuel flow. At the reduced fuel flow, the engine could not sustain flight, and the symptoms of the reduced fuel flow might easily be interpreted by the pilot as an engine failure."
|Owner/operator:||Aerial Solutions Incorporated|
|Fatalities:||Fatalities: 0 / Occupants: 2|
|Aircraft damage:|| Substantial|
|Location:||Whiteville, North Carolina -
United States of America
|Departure airport:||Whiteville-Columbus County Municipal Airport, NC (KCPC)|
|Destination airport:||Whiteville-Columbus County Municipal Airport, NC (KCPC)|
|Investigating agency: ||NTSB|
|Confidence Rating:|| Accident investigation report completed and information captured|
Probable Cause: A partial loss of engine power due to fatigue fracture of the power turbine governor spring, causing a false pneumatic signal to the fuel control and a corresponding reduction in fuel flow.
| || |
|Investigating agency: ||NTSB |
|Status: ||Investigation completed|
|Duration: ||2 years |
|Download report: || Final report|
||ASN Update Bot
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