Accident Overview
On December 14, 2017, at approximately 0854 eastern standard time, a Piper PA32-300, registration N4326X, sustained substantial damage in an accident near Hinesville, Georgia. The private pilot, who was the sole occupant, received minor injuries. The flight was being conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
Pilot Account
In a statement provided to an Federal Aviation Administration (FAA) inspector, the pilot reported being on final approach to runway 24R at Wright Army Airfield (Fort Stewart)/Midcoast Regional Airport (LHW). During the approach, he felt a shutter, followed by a loud bang. Immediately afterward, the windshield became covered in oil, and the engine experienced a complete loss of power. The pilot informed the air traffic controller that he was unable to land on the runway and that he was "going down." The airplane subsequently impacted trees approximately 2 miles short of the runway.
In the National Transportation Safety Board Pilot/Operator Aircraft Accident/Incident Report (Form 6120.1), the pilot described the event as a catastrophic engine failure wherein "the camshaft broke and blew through engine block."
Engine Examination
An FAA inspector examined the engine and observed a large hole in the crankcase above cylinder No. 4. The crankcase surrounding the hole appeared displaced from the inside outward. Further examination revealed that one connecting rod bolt and the rod cap were missing, and the connecting rod was not attached to the crankshaft. Additionally, approximately 6 inches of the camshaft had separated and was not located.
Component Analysis
The NTSB Office of Research and Engineering examined the remnants of the connecting rod, piston assembly, and pieces of the connecting rod bearing.
Bearings: Both bearing halves were deformed and flattened. One half was intact, while the other had fractured. The fracture surfaces exhibited heavy damage consistent with post-fracture damage. Undamaged portions of the fracture surface showed features consistent with tensile overstress. The fracture surface had a general rough texture with a dull luster, and adjacent areas displayed local plastic deformation in the form of thinning or necking. The mating fracture faces of the fractured bearing half also showed a circular impact imprint consistent with impact from the head of a connecting rod bolt.
Connecting Rod Bolt: The remaining connecting rod bolt had fractured mid-length. The fracture features were generally rough in texture and flat in luster, consistent with fracture from bending overstress.
Piston: The piston was intact, with the connecting rod still affixed via the piston pin. The connecting rod had fractured near the crankshaft side at the rod yoke. No cracks or indications of severe deformation were observed on any portion of the piston. The underside of the piston exhibited multiple impact and gouge marks consistent with repeated batter from adjacent or loose components. The crown, side, and piston pin showed normal wear.
Connecting Rod: All discernible fracture surfaces on the connecting rod exhibited features consistent with overstress fracture.
Due to extensive post-fracture damage to the parts, no indication of pre-existing damage was found.