Pilot Debrief

ARROW FALCON EXPORTERS INC OH-58A near Escalon, CA — 2010-02-02

Final reportWPR10LA126
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Date
2010-02-02
Location
Escalon, CA, USA
Aircraft
ARROW FALCON EXPORTERS INC OH-58A
Registration
N9286U
Category
Helicopter
Highest injury
Serious
Fatalities
0
Phase of flight
Initial climb

Probable cause

A loss of engine power during cruise flight due to the fatigue failure of the pneumatic fuel-to-governor control line. Also causal was the inadequate installation of the pneumatic line by maintenance personnel, and the pilot’s decision to continue flight with a known discrepancy.

NTSB narrative

The pilot had reported to his mechanic prior to the accident flight that the helicopter was not producing full power, was vibrating heavily, and that the DC generator caution light had illuminated. He also reported that his work load was heavy, and that he would continue onwards to return the helicopter to its home base. Shortly after takeoff the engine lost power, the pilot performed a forced landing, and the helicopter collided with terrain. Examination of the engine revealed that a stainless steel pneumatic fuel-to-governor control line had failed at its fitting. Witness marks on the line revealed that it had been rubbing against an adjacent oil line. Additionally, the pneumatic line had been bent during installation such that its surface was in contact with the connector ferrule. Analysis of the line's fracture surface revealed indications of high cycle fatigue. The fuel controller was replaced about 26 flight hours prior to the accident; replacement of the controller would have required the removal and installation of the failed line. The engine manufacturer provided installation guidance in multiple publications, and specifically cautioned against improper installations of engine lines. Examination of the DC starter-generator revealed that it had experienced a partial mechanical failure, which was likely the reason the pilot felt a vibration and observed a dc generator caution light. During the investigation the failed line was replaced, and the engine was successfully run in a test cell throughout its power range.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Pilot should not have attempted takeoff with reported maintenance issues.

NTSB coding

Evidence available

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

Docket documents11

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