Piper PA 32R-300 N5605V accident near Hector, Arkansas

Probable cause

An engine failure due to crankshaft fatigue cracking for reasons that could not be determined based on the available evidence.

NTSB analysis

The pilot reported that, during climbout, he noticed that the engine was vibrating. After leveling off the airplane, the vibration worsened, and the engine subsequently experienced a total loss of power. The pilot executed a forced landing onto a road, and the airplane impacted a fence post.

Examination of the engine revealed that the crankshaft was fractured through the No. 8 cheek position between the Nos. 5 and 6 pistons. Fatigue cracking emanated from the connecting rod journal where the No. 5 connecting rod mates. The No. 6 piston cooling nozzle was not found in its position, and its pieces were found in the bottom of the sump; the pieces were more intact than would be expected if they had been ground between the crankshaft and connecting rod for an appreciable amount of time. Also, there was no evidence of a gouge or other mechanical damage on the No. 5 connecting rod journal. Based on this evidence, it is unlikely that the fatigue cracking was initiated by the No. 6 cooling nozzle being lodged against the crankshaft after falling out of position.

About 18 months before the accident, the engine was repaired and overhauled due to a propeller strike. Further, about 4 months before the accident, maintenance personnel performed a top overhaul of the engine, and, about 1 month before the accident, maintenance personnel replaced the No. 2 cylinder. The timing of the failure suggests that an imbalance could have been introduced to the engine during one or both of the maintenance procedures, which could have resulted in the initiation of the fatigue cracking and the subsequent falling out of the No. 6 cooling nozzle; however, the exact cause of the crankshaft fatigue cracking could not be determined.

Text from the NTSB. Open the NTSB docket for CEN14LA030 for the full record.