Accident Overview
On August 21, 2023, at approximately 1048 central daylight time, a Piper PA-31-350 airplane, registration N3589X, was substantially damaged during an accident near Durant, Oklahoma. The pilot was not injured. The airplane was operating under Title 14 Code of Federal Regulations Part 91 as an aerial observation flight.
In-Flight Engine Failure
The pilot reported hearing and feeling a bang from the right side of the airplane during flight. Observation revealed a hole in the right engine nacelle and an engine fire. The pilot shut down and secured the right engine, which appeared to stop the fire, then diverted to a nearby airport.
Landing and Post-Landing Fire
While on final approach for landing, the engine fire reignited. The pilot landed the airplane, taxied clear of the runway, shut down the left engine, and egressed. The engine fire continued to burn, consuming the right engine and a majority of the fuselage.
Engine Examination Findings
An examination of the right engine revealed that the No. 2 cylinder was displaced from the engine case but remained attached via the injector manifold vent tube and injector lines. All eight of the No. 2 cylinder’s attach bolts were broken off at the case. The connecting rod cap was found lodged in the bottom of the piston. One connecting rod bolt was broken off flush in the connecting rod; the top portion was not located. The other connecting rod bolt remained in the connecting rod cap with the nut also not located. One side of the lower connecting rod flange was bent back toward the piston, capturing the nut and remaining portion of the broken bolt. Neither bearing half was identified. Numerous impact marks were noted on the piston, cylinder, and case.
Maintenance History
A review of maintenance records indicated that the engine was last overhauled on March 20, 2019, and installed on the airplane on October 1, 2020. The airplane had accrued about 900 hours since the overhaul.