Pilot Debrief

ROBINSON HELICOPTER R44 near Hochatown, OK — 2023-10-01

Final reportCEN24LA004
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Date
2023-10-01
Location
Hochatown, OK, USA
Aircraft
ROBINSON HELICOPTER R44
Registration
N379SH
Category
Helicopter
Highest injury
None
Fatalities
0
Phase of flight
Initial climb

Probable cause

A total loss of engine power during a practice autorotation due to the improper engine idle setting and rigging of the carburetor heat control which resulted in a hard landing.

NTSB narrative

The pilot reported that he was conducting a practice autorotation during a proficiency flight about 400 ft above ground level (agl). As he reduced the engine speed to idle, the engine lost total power. The pilot entered an autorotation and completed a forced landing to a field. The helicopter landed hard and the tailboom was severed by the main rotor blades. Examination of the engine revealed that the idle speed was set below 50 percent, which was below the manufacturer’s recommendation of 60 to 65 percent. Additionally, the carburetor heat control cable was rigged improperly, and therefore, was jammed in the full heat position. The combination of these factors would have likely made the engine more susceptible to losing power, especially with an abrupt power reduction initiated by the pilot during the simulated autorotation. After reviewing the available maintenance records, it is possible the engine idle speed was improperly set, and the carburetor heat control was improperly rigged when the engine was overhauled and installed in the helicopter; however, investigators were unable to establish exactly when the misrigging took place or why it was not noticed during subsequent maintenance.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Pilot could have checked carburetor heat control before simulating engine power loss.

NTSB coding

Evidence available

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

Docket documents8

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