NTSB Identification: ERA12LA422
14 CFR Part 91: General Aviation
Accident occurred Thursday, June 28, 2012 in Mc Kinnon, TN
Probable Cause Approval Date: 09/30/2013
Aircraft: MOONEY M20J, registration: N174JB
Injuries: 1 Serious,1 Minor.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

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.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

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.

Full narrative available

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