Piper PA28 N7355W accident near Steele, Missouri

Probable cause

The loss of oil pressure for a reason that could not be determined leading to failure of the engine connecting rod.

NTSB analysis

The pilot stated that during cruise flight, following a low oil pressure indication, the engine started sounding unusual, began shaking violently, and quit. He determined that he would not be able to glide to the nearest airport and executed a forced landing during which, the wing sustained substantial damage.

A post-accident examination revealed that the No. 2 cylinder connecting rod was separated from the crankshaft and there was a large hole in the engine crankcase. Examination of the failed connecting rod components revealed that the connecting rod strap failed due to fatigue fractures in both arms of the strap. Fretting damage on the mating surface between the connecting rod and cap indicated movement at the joint. Additionally, there were circumferential marks on the connecting rod strap and galled bearing material indicating that the bearing had spun within the connecting rod.

Based on the available information the failure of the connecting rod was likely precipitated by the loss of oil pressure, ultimately resulting in the failure of the connecting rod. The reason for the loss of oil pressure could not be determined.

Text from the NTSB. Open the NTSB docket for CEN20LA189 for the full record.