Pilot Debrief

MOONEY M20J near Mc Kinnon, TN — 2012-06-28

Final reportERA12LA422
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Date
2012-06-28
Location
Mc Kinnon, TN, USA
Airport
M93
Aircraft
MOONEY M20J
Registration
N174JB
Category
Airplane
Highest injury
Serious
Fatalities
0
Phase of flight
Approach

Probable cause

The separation of the piston connecting rod from the crankshaft due to inadequate installation from a mechanic, resulting in a total loss of engine power.

NTSB narrative

The pilot was conducting a formation flight when the airplane’s engine experienced a loss of power. The pilot and his instructor then conducted a forced landing to a runway and landed long, with the airplane departing the surface and coming to rest in a field. Post accident examination revealed that the number three piston connecting rod cap separated from the piston connecting rod when the hardware came loose and the connecting rod disconnected during flight. Maintenance records showed that the engine had been overhauled several years prior to the accident. It is likely that the mechanic did not properly install the connecting rod bolts and nuts, which resulted in the number three piston connecting rod disconnecting during flight, and subsequent loss of engine power.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
CFI should have aborted the approach earlier due to engine issues.

NTSB coding

Evidence available

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

Docket documents9

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