CEN24LA155 · Piper PA-32-301

The pilot was conducting a cross-country flight when the engine rpm slightly decreased. He attempted to troubleshoot but the engine surged before it lost all power. The pilot then prepared for a forced landing to a field. During the landing roll, the airplane impacted trees at the edge of a down-sloping, wet field. The airplane came to rest upright and sustained substantial damage to the stabilator, fuselage, and both wings. Postaccident examination of the engine revealed that the engine crankshaft had fractured in two locations due to fatigue. The fatigue crack initiation sites were located near rotational wear bands. The inner diameter surfaces and edge faces of two sets of the main bearing journals exhibited severe gouging, cracking, and material spalling, consistent with rotational abrasive wear. Based on the damage, the degraded bearings likely prevented sufficient lubrication, leading to excessive heating and scoring that helped initiate fatigue cracking of the crankshaft. The engine was most recently overhauled about 28 years and 2,439 flight hours before the accident. The manufacturer’s recommended time between overhaul (TBO) interval was 2,000 flight hours or 12 years, whichever occurred first. Although not required for Part 91 operations, following the manufacturer’s recommended overhaul procedures likely would have prevented the bearing failure and subsequent loss of engine power.

Verbatim NTSB analysis and probable cause from the NTSB dataset