CEN21LA031

During a night training flight, the flight instructor and student pilot experienced a total loss of engine power and executed a forced landing onto rough terrain, which damaged the airplane’s right-wing spar. Postaccident examination of the airplane revealed a nearly empty oil reservoir and oil residue on the underside of the fuselage and elevator, with significant thermal damage to the engine. The examination also found a disconnected oil line fitting. No material or structural anomalies were noted with the oil line or fitting. The engine had been recently overhauled, and the two mechanics who performed the overhaul stated it was very possible that they did not properly torque the oil line fitting. Following the accident, the overhaul facility implemented a requirement to torque seal applicable components to help ensure compliance with torque specifications.

On October 20, 2020, about 2020 central daylight time, a Piper PA-28-140 airplane, N5932U, was substantially damaged when it was involved in an accident near Buda, Texas. The flight instructor and student pilot were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 flight. The flight instructor stated that while in cruise flight during the night training flight, the engine started to lose rpm, vibrate, and subsequently lost all power. During the descent, the flight instructor and student coordinated to select the closest runway and attempted to land at a private airport. After noticing the airplane was not able to the glide to the runway, the flight instructor conducted a forced landing onto rough terrain, which damaged the right-wing spar. A postaccident examination revealed significant thermal damage to the engine, a nearly empty oil reservoir, and a disconnected oil line fitting to the oil pressure indicator. Oil residue was trailing on the underside of the fuselage and the bottom of the elevator surface. Examination of the oil line fitting revealed no material or structural anomalies with the oil line or fitting. The accident was the airplane’s second flight following an engine overhaul due to a propeller strike. The two mechanics who conducted the overhaul stated that since both were involved and no procedure was in place to “verify all lines” were torqued properly, it was very possible the oil line fitting may have been missed. Following the accident, the overhaul facility implemented a requirement to torque seal applicable components during an overhaul to ensure compliance with torque specifications. This best practice is described in NTSB Safety Alert SA-056, “Take Time to Torque” (available at https://www.ntsb.gov/Advocacy/safety-alerts/Documents/SA-056.pdf) as well as in a maintenance article highlighting the importance of proper torque protocols that was published in the July 2018 FAA Safety Brief (located in the docket for this investigation).