ERA23LA197

The pilot reported that, during a flight in visual conditions, he heard a “boom” from the propeller hub. The propeller immediately began to oscillate and shudder violently, accompanied by severe engine vibration and oil loss. He shut the engine down and executed a forced landing to a field that resulted in structural damage to the airplane. The pilot sustained serious injuries. A teardown examination of the engine after recovery of the wreckage revealed that the No. 1 connecting rod cap separated from the rod during flight, resulting in catastrophic engine damage. Damage to the rod cap bolts and nuts was consistent with the nuts loosening and backing out over time. There was no evidence of heat distress on the affected parts. A review of the aircraft maintenance logbooks revealed that the last overhaul of the engine was performed more than 30 years before the accident. A service instruction issued by the engine manufacturer instructs all engine models to be overhauled within twelve calendar years of the date they first entered service or of the last overhaul.

On April 14, 2023, about 1440 eastern daylight time, a Cessna 177RG, N7542V, was substantially damaged when it was involved in an accident near Crestview, Florida. The pilot was seriously injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that he departed Destin Executive Airport (DTS), Destin, Florida, to practice RNAV and ILS approaches in visual flight rules conditions at the Bob Sikes Airport (CEW), Crestview, Florida. The airplane departed DTS and flew toward CEW without incident; however, shortly after the pilot was cleared for his first practice approach, he heard a “boom” from the propeller hub. The propeller immediately began to shudder violently and oscillate in a semi-oval pattern. The fuselage also began to vibrate intensely, and the pilot observed oil on the propeller hub, which subsequently coated the windshield and impaired visibility. The pilot elected to shut down the engine and identified a field for a forced landing; however, as he approached the field he noticed obstacles and a marsh. He kept the landing gear retracted and landed in an area of cut trees. After touchdown, the airplane slid approximately 100 ft before coming to a stop. An inspector with the Federal Aviation Administration responded to the accident site and examined the wreckage. The engine firewall was buckled, with complete structural failure at the engine mounts. The left, outboard wing section was bent upward, and the vertical stabilizer leading edge and horizontal stabilator were buckled. There was damage to the lower fuselage and the landing gear was completely retracted. Oil was present in the engine; however, the engine was tilted forward in the mount so an accurate quantity could not be established. There was evidence of oil leakage on the right side of the aircraft. The wreckage was recovered to a storage facility where an additional examination was performed. During the engine examination, the propeller was rotated manually through 90° of travel before it stopped and could not be rotated further. The oil suction screen contained about a teaspoon of metallic flakes, and metal particles were present throughout the pleats of the oil filter element. The No. 3 cylinder was removed and the No. 3 connecting rod beam was cut to gain access to the rear portion of the engine interior. Damage to the cylinder skirts of the Nos. 1, 2, and 4 cylinders prevented their removal. The No.1 cylinder barrel was cut and the cylinder removed from the engine. The No.1 connecting rod was found separated from the No.1 crankshaft rod journal and damaged from impact with the internal engine components. The No.1 rod cap was found to be damaged and found inside the engine crankcase. Two portions of the No.1 connecting rod were also found inside the crankcase with rod bolt holes. Both rod bolt threaded ends were found in the crankcase. No rod nuts were observed on the threaded ends. A portion of a threaded rodnut was observed inside the crankcase. Fragments of the No.1 rod bearings were found inside the crankcase. The No.1 crankshaft rod journal did not exhibit scoring or discoloration consistent with overheating. No indications of overheating of the other rod journals or crankshaft journals were observed. A review of the aircraft maintenance logbooks revealed that, as of the last annual inspection on September 16, 2022, the engine had accumulated 1,624.61 hours since its last overhaul. The pilot, who owned the airplane, purchased it on September 10, 2021. That overhaul was completed on February 28, 1993, more than 30 years before the accident. According to Lycoming Service Instruction No. 1009BE, dated April 24, 2020, “all engine models are to be overhauled within twelve (12) calendar years of the date they first entered service or of last overhaul. This calendar year time period TBO is to mitigate engine deterioration that occurs with age, including corrosion of metallic components and degradation of non-metallic components such as gaskets, seals, flexible hoses and fuel pump diaphragms.”