Pilot Debrief

HILLER UH-12E near Los Banos, CA — 2010-02-02

Final reportWPR10LA127
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Date
2010-02-02
Location
Los Banos, CA, USA
Aircraft
HILLER UH-12E
Registration
N36MV
Category
Helicopter
Highest injury
None
Fatalities
0
Phase of flight
Approach

Probable cause

A partial loss of engine power due to a failure of the throttle interconnect hardware, which resulted in a hard landing.

NTSB narrative

The pilot of the helicopter had just completed an aerial application flight and was returning to land. As he approached the landing area, he began to apply power, but the engine did not respond. He continued to twist the throttle, but it felt loose with no resistance and the engine speed did not change. He aborted the landing approach and performed a run-on landing in a field; during the approach the engine speed began to decrease and the helicopter landed hard, causing substantial damage to the tail boom and lower fuselage. Postaccident examination revealed that the throttle control attach fitting located in the aft section of the collective control had become separated. The nuts and bolts attaching the fitting were not located. The lack of witness marks on the throttle fitting indicates that either the attachment bolt failed or rapidly unscrewed from its associated nut. The disconnection resulted in a loss of engine control and subsequent partial loss of engine power. The last annual inspection occurred 11 months and 250 flight hours prior to the accident.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Pilot could have performed a controlled landing earlier after engine failure.

NTSB coding

Evidence available

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

Docket documents6

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