Accident Details
On September 14, 2023, about 1300 central daylight time, a Cessna 182P airplane, registration N8443M, sustained substantial damage in an accident near Prospect, Tennessee. The private pilot and one passenger received minor injuries. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal cross-country trip from Tuscaloosa National Airport (TCL), Alabama, to Lebanon Municipal Airport (M54), Tennessee.
About one hour into the flight, while cruising at 3,500 feet mean sea level, the pilot reported a sudden severe engine vibration and loss of power. He reduced throttle to attenuate the vibration. Uncertain whether the airplane could clear a large forested area ahead, he chose to land in a soybean field. After touchdown, the nose landing gear struck a ditch and separated, causing the airplane to nose over and come to rest inverted. The pilot called 911 and was met by first responders.
Examination Findings
Federal Aviation Administration inspectors examined the wreckage at the scene. The airplane was found inverted in the soybean field with no evidence of fire. Substantial damage was noted to the fuselage and empennage.
After recovery, the engine was inspected while still mounted on the airframe. The rocker covers were removed to examine cylinder heads and valve action. Cylinders Nos. 1 through 5 appeared normal with correct valve action. When the No. 6 cylinder rocker cover was opened, pieces of the exhaust valve rocker boss, rocker, washers, and rocker shaft were found loose inside. The exhaust valve was closed. The rocker boss exhibited two fractures.
The loose parts from the No. 6 cylinder were sent to the National Transportation Safety Board Materials Laboratory. One rocker boss fragment showed features consistent with fatigue, initiating at multiple sites along the bore surface that had been in contact with the arm. The other fragment failed due to overstress, with features consistent with rapid fracture of an aluminum casting.
Maintenance History
A review of the engine logbook indicated that the engine cylinders were removed, overhauled, and reinstalled on May 18, 2020, at a total aircraft time of 2,609.8 hours. At the time of the accident, the airplane had accumulated approximately 154 hours since the cylinder overhaul.