Pilot Debrief

BELL 407 near Bow, NH — 2008-12-22

Final reportERA09LA105
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Date
2008-12-22
Location
Bow, NH, USA
Aircraft
BELL 407
Registration
N407GB
Category
Helicopter
Highest injury
Serious
Fatalities
0
Phase of flight
Climb

Probable cause

An interruption of fuel flow for undetermined reasons, which resulted in an engine flameout.

NTSB narrative

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.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Pilot could have chosen to delay departure until weather improved.

NTSB coding

Evidence available

  • Photos
  • 13 docket documents
View NTSB final reportView NTSB docket

Docket documents13

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