N729CW – BEECH A36 – 2024-03-17 NTSB Accident Report

On March 17, 2024, at 0825 eastern daylight time, a Beech A36 airplane, N729CW, was substantially damaged when it was involved in an accident near Blackshear, Georgia. The private pilot and two passengers were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

The pilot reported a reduction in engine power and an inability to climb as he was ascending through 11,000 ft mean sea level. The pilot observed a loss of oil pressure followed by a rough running engine that eventually seized. The pilot made a forced landing to a rural road and impacted a tree, which resulted in substantial damage to the right wing and engine mounts.

A review of photographs taken by first responders revealed a large amount of residual oil on the inside of the engine cowling. The pilot reported that he checked the oil before departure and added 1 quart of oil to the 11 quarts present, for a total of 12 quarts.

After the accident, the airplane was relocated to a secured facility and the engine and turbocharger were removed from the airframe by salvage personnel and shipped to Continental Aerospace Technologies, Mobile, Alabama, for further examination. The mechanic who removed the turbocharger reported there were no loose fittings or oil leaks observed when the turbocharger was removed. On a subsequent visit to the salvage facility by NTSB personnel, the turbocharger’s oil scavenge line was examined and found clear of debris. There were no leaks or residual oil observed on the belly of the airplane.

The turbocharger was disassembled and inspected. The internal components, including the rotor assembly, bearings, and housing, showed no evidence of damage and were covered in a thick coat of oil and debris. No mechanical deficiencies were observed that would have precluded normal operation.

Examination of the engine revealed a large hole in the top of the crankcase between the No. 3 and No. 4 cylinders. The crankshaft was seized and could not be manually rotated. The oil filler cap was secure to the engine. The oil sump was filled with a large amount of metallic debris including a connecting rod and lifters. The oil scavenger pump and the oil pump were removed and rotated manually. Both pumps were disassembled and no mechanical deficiencies were observed.

Disassembly of the engine revealed multiple failed and heavily damaged connecting rods; indications of overheating consistent with oil starvation were found on the Nos. 2 through 5 connecting rods. The Nos. 4 and 5 connecting rods exhibited the most damage and both released from the crankshaft. The camshaft was also sheared and the No. 4 push rods were bent. All of the oil ports were clear except for the No. 5 connecting rod journal, which was blocked, consistent with having been welded over from heat during the failure sequence. The crankshaft would not rotate due to internal damage of the engine; thus, compression and engine timing could not be established.

The airplane was equipped with a Garmin GEA-24 engine indicating system; however, the unit did not have recording capability and no engine data was recovered from the device.

Review of the engine’s maintenance logs indicated that, at the time of the accident, the total operational time of the engine was 2,748 hours. The engine had undergone a major overhaul 871 operational hours before the accident.