Mooney M20J N2159D accident near Ozark, Arkansas

Probable cause

The failure of a connecting rod due to oil starvation.

NTSB analysis

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.

Text from the NTSB. Open the NTSB docket for CEN12LA326 for the full record.