Pilot Debrief

BELL 47D1 near Ahwahnee, CA — 2011-09-27

Final reportWPR11LA469
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Date
2011-09-27
Location
Ahwahnee, CA, USA
Aircraft
BELL 47D1
Registration
N9158R
Category
Helicopter
Highest injury
Serious
Fatalities
0
Phase of flight
Descent

Probable cause

The pilot’s failure to maintain adequate main rotor rpm during the landing approach, which resulted in a loss of control.

NTSB narrative

The pilot and mechanic were on a local area flight to warm the oil before changing the oil lines. As they returned, the pilot slowed the helicopter and initiated a gradual descent to the landing site. The main rotor rpm decreased. As they continued the descent, the clearance from the trees surrounding the landing area was minimal. The pilot attempted to avoid the trees as he tried to regain main rotor rpm. The helicopter impacted a tree and descended nose down into the terrain. According to the mechanic and pilot, they encountered no mechanical anomalies during the flight.

Analysis

Primary failure mode
Loss of control
First missed decision gate
Pilot could have chosen a different landing area to avoid trees.

NTSB coding

Evidence available

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

Docket documents5

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