Pilot Debrief

MOONEY M20J near Ozark, AR — 2012-05-25

Final reportCEN12LA326
Sign in to save
Date
2012-05-25
Location
Ozark, AR, USA
Airport
7M5
Aircraft
MOONEY M20J
Registration
N2159D
Category
Airplane
Highest injury
Minor
Fatalities
0
Phase of flight
Cruise

Probable cause

The failure of a connecting rod due to oil starvation.

NTSB narrative

The pilot reported that, during cruise flight, he noticed a change in engine sound and that he subsequently scanned the engine gauges, which were all within normal operating parameters. Shortly after, the engine rpm began to drop, the pilot heard a "pop" or "bang," and the propeller stopped rotating. The pilot attempted to glide the airplane to an alternate airport, but the airplane overshot the runway. The pilot then attempted to land on a nearby road, and the left wing of the airplane struck the ground during the maneuver. Oil streaking was observed on the airplane's exterior. Postaccident examination of the engine revealed that no oil was not present in the engine. During disassembly of the engine, the No. 4 connecting rod cap was found fractured, and pieces of the cap were found within the crankcase. Evidence indicated that the No. 4 connecting rod failed due to frictional heating and impact associated with a bearing failure. The Nos. 1 to 3 connecting rods and connecting rod bolts showed varying degrees of heat discoloration, and the evidence of heating in the Nos. 2 and 4 connecting rods indicated that the No. 4 bearing failure was due to lack of oil in the connecting rod bearings. The cause of the oil starvation could not be determined.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Pilot could have conducted a precautionary landing upon noticing engine sound change.

NTSB coding

Evidence available

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

Docket documents13

Related mishaps