Pilot Debrief

REIMUS Sonex FR1 near Paso Robles, CA — 2009-03-25

Final reportWPR09LA166
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Date
2009-03-25
Location
Paso Robles, CA, USA
Airport
PRB
Aircraft
REIMUS Sonex FR1
Registration
N1006N
Category
Airplane
Highest injury
Serious
Fatalities
0
Phase of flight
Climb

Probable cause

A total loss of engine power during cruise flight due to the pilot/builder’s failure to follow the engine manufacturer’s maintenance instructions and apply the correct torque to the rocker arm nuts during maintenance.

NTSB narrative

During cruise flight the engine of the experimental amateur-built airplane began to run rough and then lose all power. The pilot/builder then performed a forced landing in a vineyard. During the landing sequence, the airplane struck a trellis and sustained substantial damage to the firewall and right wing. Postaccident examination of the engine revealed that the valve clearance for three of the cylinder head rocker arms was beyond adjustment tolerances; additionally, one of the pushrods was loose within the cylinder head and did not make contact with its associated rocker arm. The pilot performed maintenance about 24 flight hours prior to the accident flight which included adjusting the rocker arm valve clearance. The pilot noted in the engine logbook that the valves were gapped at the manufacturer’s recommended setting. The pilot was not aware of the engine manufacturer's requirement to apply a specific torque to the valve rocker adjustment nuts during adjustment, and as such, did not tighten the nuts to the recommended torque level.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Pilot could have performed maintenance per manufacturer's torque recommendations.

NTSB coding

Evidence available

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

Docket documents8

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