ERA24LA388

The pilot was conducting a local “break-in” flight for the airplane’s recently-installed engine. During the initial climb, the engine’s rpm started to decline, followed by a total loss of engine power. The pilot performed a forced landing to a field and the airplane nosed over during the landing roll, resulting in substantial damage to the airplane’s fuselage, wings, rudder, and vertical stabilizer. A postaccident examination of the airplane revealed that the engine’s crankshaft was not free to rotate. The engine’s front main bearing was discolored and exhibited rotational abrasion at its rear oil passage area and corresponding crankshaft surface. Additionally, insect-related debris, soil/clay/mud, and lubricating oil were obstructing the crankcase oil header and the front main bearing’s aft oil passage. The signatures of lubrication distress observed on the front main bearing were consistent with oil starvation as a result of the obstructions found within the engine’s lubrication system. Review of the engine’s maintenance records showed that crankcase was repaired nearly 12 years before the accident and that the engine was overhauled 2 years later. The engine did not accrue any time in service prior to its installation on the accident airplane about 1 month before the accident (about 10 years after the overhaul). The mechanic who performed the engine overhaul reported that the crankcase was stored in a hangar for several months before he acquired it and that he did not remember cleaning and verifying that the oil passages of the crankcase were unobstructed before assembly. According to the engine manufacturer’s overhaul manual, all oil passages should be cleaned with suitable brushes then flushed thoroughly with clean solvent and compressed air. Based on the available evidence, an insect likely infiltrated the crankcase and made a nest in the oil passages during the more than 2 years it was stored. Maintenance personnel then failed to clean and verify the oil passages were free of obstruction before assembly of the engine, which resulted in a lack of lubrication to the front main bearing and a subsequent total loss of engine power.

On September 20, 2024, about 1543 eastern daylight time, a Cessna 172K airplane, N7037G, was substantially damaged when it was involved in an accident near Spartanburg, South Carolina. The commercial pilot sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 flight test. The pilot reported that the purpose of the flight was to perform a local “break-in” of the airplane’s recently installed engine. There were no engine anomalies noted during the preflight inspection, engine run-up checks, and subsequent takeoff roll. During the airplane’s initial climb at an altitude of about 100 ft, the pilot observed an rpm decline followed by a total loss of engine power. With no remaining runway and unable to return to the airport, the pilot chose to perform a forced landing in a field. During the landing roll, the airplane nosed over and came to rest inverted about 0.3 miles northeast of the runway. The airplane’s fuselage, wings, rudder, and vertical stabilizer sustained substantial damage. The airplane was recovered to a secure facility, and a postaccident examination was conducted. There was no evidence of an oil leak and about 8 quarts of oil were observed in the engine oil sump. Attempts to rotate the crankshaft were unsuccessful. The four cylinders were removed with no anomalies noted to their interiors and residual oil was observed on the valvetrain and internal engine components. The four connecting rods rotated freely on the crankshaft when facilitated by hand. There was no debris observed in the oil pump suction screen or oil filter media. Further disassembly of the engine revealed that the front main bearing was discolored and exhibited rotational abrasion at its rear oil passage area and corresponding crankshaft surface. There were no anomalies noted to the bearing’s front oil passage area or crankshaft surface. The Nos. 2 and 3 main bearings were unremarkable. There were no anomalies noted to the oil pump. An oil passage continuity check revealed an obstruction between the oil header and the front main bearing’s aft oil passage. Additionally, an oil passage was obstructed to the No. 4 cylinder intake cam follower bore. All other oil passages were free of obstruction. The right front crankcase was sectioned, and the obstruction was extracted from the oil passage. The debris recovered from the cam follower bore and front main oil passages was a gritty material and was shipped to the NTSB Materials Laboratory for further examination. The laboratory examination found that the material was consistent with insect-related debris, soil/clay/mud and lubricating oil. A review of the engine’s maintenance records showed that the engine was overhauled on October 12, 2014, at which time it was converted from an O-320-E2A to an O-320-D2G, in accordance with Lycoming Service Instruction 1304J. According to the records, the engine did not accrue any time in service until it was installed on the accident airplaneon September 20, 2024. Among the records was a crankcase repair facility work order and FAA form 8130-3 dated March 30, 2012. Additionally, there was an invoice for engine hardware dated February 07, 2014. According to the Lycoming overhaul manual, all oil passages are to be cleaned with suitable brushes, and after which flushed thoroughly with clean solvent and compressed air. The crankcase repair facility reported that among their repair paperwork was a checklist that included a step to clear oil galleys and holes, and to re-clean before assembly. The mechanic who performed the engine overhaul reported that crankcase was owned by another individual and stored in a hangar for several months before his acquisition of the crankcase and subsequent assembly of the engine. He further stated that he did not remember cleaning and verifying that the oil passages of the crankcase were unobstructed before assembly.