Pilot Debrief

GLASAIR SH2 near Passadumkeag, ME — 2018-07-11

Final reportERA18LA190
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Date
2018-07-11
Location
Passadumkeag, ME, USA
Aircraft
GLASAIR SH2
Registration
N352GL
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Climb

Probable cause

A total loss of engine power due to a fatigue fracture of the crankshaft.

NTSB narrative

While in cruise flight, the experimental, amateur-built airplane's engine started to run "rough" and lost partial power. The pilot checked the engine gauges, noted no irregularities, and unsuccessfully attempted to restore engine power by turning the fuel boost pump on. Within about 30 seconds of the initial power loss, the engine lost total power and the propeller stopped. The pilot performed a forced landing to a bog and the airplane came to rest inverted, resulting in substantial damage to the empennage. Disassembly and examination of the engine revealed that the crankshaft had fractured at the No. 4 cylinder journal. Further examination of the fracture surface revealed fatigue striations consistent with fatigue crack propagation. These striations were finely spaced and exhibited changing or erratic thicknesses on different areas of the fracture surface, consistent with propagation through high-cycle fatigue. The reason for the crack initiation could not be determined. According to the engine maintenance log, the engine experienced a propeller strike during a landing incident about 5 years and 368 flight hours before the accident. The pilot elected not to have the propeller strike or sudden stoppage inspection performed, since it was not mandatory for non-certificated engines.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Performing a prop strike inspection after the previous incident could have prevented failure.

NTSB coding

Evidence available

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

Docket documents7

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