CEN20LA189

The pilot stated that during cruise flight, following a low oil pressure indication, the engine started sounding unusual, began shaking violently, and quit. He determined that he would not be able to glide to the nearest airport and executed a forced landing during which, the wing sustained substantial damage. A post-accident examination revealed that the No. 2 cylinder connecting rod was separated from the crankshaft and there was a large hole in the engine crankcase. Examination of the failed connecting rod components revealed that the connecting rod strap failed due to fatigue fractures in both arms of the strap. Fretting damage on the mating surface between the connecting rod and cap indicated movement at the joint. Additionally, there were circumferential marks on the connecting rod strap and galled bearing material indicating that the bearing had spun within the connecting rod. Based on the available information the failure of the connecting rod was likely precipitated by the loss of oil pressure, ultimately resulting in the failure of the connecting rod. The reason for the loss of oil pressure could not be determined.

On May 22, 2020, about 1415 central daylight time, a Piper PA-28-180, N7355W, was substantially damaged when it was involved in an accident near Steele, Missouri. The pilot and passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot said that while in cruise flight at 3,000 ft mean sea level (msl), he noticed that the oil pressure gauge read zero. Believing that the gauge was faulty, he started a turn to return to the departure airport to have it checked. During the turn, he noticed that the oil pressure came back to normal, but a short time later it went back to zero. Subsequently the engine started sounding unusual, began shaking violently, oil blew onto the windscreen. and the engine quit. When he determined that he would not be able to glide to the nearest airport, he executed a forced landing to a cotton field. The airplane sustained substantial damage to the left wing during the forced landing. Figure 1. Photograph of the airplane at the accident site. During a post-accident examination, oil was present on the exterior of the airplane but no evidence of a preimpact oil leak was discovered. The examination revealed that the No. 2 cylinder connecting rod was separated from the crankshaft and there was a large hole in the engine crankcase. Examination of the failed connecting rod components revealed that the connecting rod strap failed due to fatigue fractures in both arms of the strap. Fretting damage on the mating surface between the connecting rod cap and strap indicated movement at the joint. Additionally, there were circumferential marks on the connecting rod strap and galled bearing material indicating that the bearing had spun within the connecting rod. Figure 2. Photograph of the airplane’s engine showing the broken connecting rod and damage to the engine case. Review of the engine maintenance records indicated that the most recent engine overhaul was completed on September 11, 1998. The most recent annual inspection was completed on May 5, 2020, and the engine had accumulated 1063.77 hours since overhaul as of that date. Lycoming Service Instruction 1009BE, dated April 24, 2020, listed an operating hour time between overhaul of 2,000 hours for the O-360-A3A, however, the service instruction further stated: “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.”