Pilot Debrief

ROBINSON HELICOPTER COMPANY R44 II near Valley Center, CA — 2009-09-20

Final reportWPR09LA460
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Date
2009-09-20
Location
Valley Center, CA, USA
Airport
RNM
Aircraft
ROBINSON HELICOPTER COMPANY R44 II
Registration
N4174P
Category
Helicopter
Highest injury
Serious
Fatalities
0
Phase of flight
Approach

Probable cause

The failure of the engine’s camshaft due to fatigue of unknown origin.

NTSB narrative

The pilot was performing a pinnacle landing on a large boulder. As he approached the landing zone at an altitude of between 50 and 75 feet above ground level he heard a popping sound followed by a complete loss of engine power. He performed an autorotation, during which the helicopter sustained substantial damage to the fuselage and tail boom. during the hard landing. The helicopter was manufactured about 11 months prior to the accident, had accumulated about 130 total flight hours, and was equipped with its original engine. Examination of the engine revealed that the camshaft had separated into two sections at the forward relief radius of the number six exhaust cam lobe. The fracture surfaces were damaged by the continued rotation of the engine just after the failure; however, the remaining surfaces exhibited features consistent with fatigue. The origin of the fatigue could not be determined. No other anomalies were noted with the engine or airframe. According to the engine manufacturer, the camshaft supplier had produced 4,870 camshafts of the accident type. All of these camshafts have since been installed in similar engines. A search of the Federal Aviation Administration (FAA) Service Difficulty Report (SDR) database revealed no evidence of a similar camshaft separation. Additionally, the engine manufacturer reported no prior instances of any camshaft which had failed in such a manner.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Pilot could have chosen a different landing zone or aborted the landing attempt.

NTSB coding

Evidence available

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

Docket documents11

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