NTSB Identification: ERA09LA105
14 CFR Part 91: General Aviation
Accident occurred Monday, December 22, 2008 in Bow, NH
Probable Cause Approval Date: 12/20/2010
Aircraft: BELL 407, registration: N407GB
Injuries: 1 Serious.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
Two days before the accident, the helicopter landed at an airport due to en route snow. On the day of the accident, company personnel spent about 5 hours cleaning and deicing it. The pilot subsequently conducted multiple ground and air taxi runs before departing toward his home heliport. About 45 minutes into the flight, when the helicopter was about 900 feet over tree-covered terrain, the engine lost power. The pilot then performed an approximately 180-degree autorotation to a curved street. The helicopter landed hard and sustained substantial damage to the fuselage. Prior to the loss of engine power, the pilot did not observe any caution or warning lights, and the FADEC (Full Authority Digital Engine Control) remained in the automatic mode. The pilot also noted no unusual noises or yawing of the helicopter prior to the loss of engine power. A subsequent download of the helicopter's incident recorder revealed "Engine Flameout," "Nr Droop," and "Ng Exceedance Low" faults. It also indicated that when the flameout detection occurred, "Fuel Enable" and "Auto Relight" functions became active. Subsequent examinations of the airframe, including the fuel supply system, revealed no anomalies that would have resulted in a flameout. The electronic control unit was downloaded, with no faults noted. The electronic control unit and the hydro mechanical unit were examined with no anomalies noted. The engine was mounted in a test cell and successfully run with no discrepancies noted. During a later engine test run, the fuel was intentionally shut off through a solenoid, and except for rotor rpm, the incident recorder indicated the same faults as noted in the accident sequence, confirming that the loss of engine power likely occurred due to an interruption of fuel flow for undetermined reasons.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: An interruption of fuel flow for undetermined reasons, which resulted in an engine flameout. Full narrative available
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