Pilot Debrief

STINSON 108 near Batesburg, SC — 2022-07-23

Final reportERA22LA333
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Date
2022-07-23
Location
Batesburg, SC, USA
Aircraft
STINSON 108
Registration
N6020M
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Cruise

Probable cause

The fatigue failure of the crankshaft gear, resulting in a total loss of engine power.

NTSB narrative

Shortly after takeoff the engine sustained a total loss of engine power caused by fatigue failure of the crankshaft gear, necessitating the pilot to perform an off-airport forced landing that resulted in substantial damage. The fatigue fracture initiated from multiple origins at a corner of a keyway cut in the gear. The crankshaft gear underwent magnaflux inspection and was approved for return to service associated with an engine overhaul nearly 8 years and 247 hours earlier. While there was no evidence of plating at the fatigue initiation site, it could not be determined from the available evidence whether the fatigue existed in the part at the last inspection or how fast the fatigue crack was growing.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Proper maintenance checks could have identified the crankshaft gear issue.

NTSB coding

Evidence available

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

Docket documents8

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