Accident Overview
On May 26, 2020, at approximately 1430 eastern daylight time, a Piper PA-24-250 (registration N5948P) was substantially damaged during a forced landing near South Boston, Virginia. The private pilot, the sole occupant, was not injured. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
Preflight and Departure
The pilot reported performing a preflight inspection that included checking each wing fuel tank sump drain and the gascolator, finding no contaminants. He also inspected flexible hoses in the engine compartment for condition and security, looked for fuel stains, and checked the P-leads. During the engine run-up before departure, magneto drops were about 25 rpm or less from each magneto.
Loss of Engine Power
After takeoff, the pilot proceeded toward William M Tuck Airport (W78) in South Boston. While on a close-in downwind leg for runway 19 at an altitude of 1,200 ft mean sea level, the engine experienced a sudden total loss of power. The pilot activated the auxiliary fuel pump, moved the fuel selector from the left tank (the takeoff tank) to the right tank, and set the mixture control to full rich, but engine power was not restored.
Forced Landing
The pilot turned toward the approach end of runway 19 with the flaps and landing gear retracted, maintaining 80 mph. The airplane impacted an obstruction light, touched down in tall, thick grass on airport property, and slid an unknown distance before coming to rest upright. The aircraft was subsequently recovered to W78 for engine examination.
Engine Examination
An FAA inspector examined the engine after recovery. Hand rotation of the crankshaft did not rotate the magnetos or produce valve train action at the No. 1 cylinder. When the accessory case was removed, rotation of the crankshaft did not cause the crankshaft gear to rotate. The crankshaft gear attachment bolt, marked with “2247” on its head, was found unsecured and loose. The bolt, fractured remnants of the lockplate, and the crankshaft gear were removed. The alignment dowel pin was sheared. The intact portion of the accident lockplate was similar in profile to an un-bent exemplar lockplate. The left and right magneto driven gears, crankshaft gear, and crankshaft gear attachment bolt were undamaged. It could not be determined if Loctite anti-seize compound was present on the lower threads of the bolt.
The crankshaft gear drives two idler gears in the accessory gearbox, which in turn drive the camshaft, engine-driven fuel pump, vacuum pump, and magneto drive couplings.
Maintenance History
Engine maintenance records showed that the engine was overhauled by an airframe and powerplant (A&P) mechanic in 2011 and had accrued about 253 hours since overhaul at the time of the accident. The maintenance record entry for the overhaul did not specify installation of a new crankshaft gear attachment bolt or lockplate, nor the final torque value for that bolt as required by Lycoming Service Bulletin 475C, dated January 30, 2003.
According to the FAA inspector, the A&P mechanic who performed the overhaul was deceased; therefore, it could not be determined what procedures were used to install the crankshaft gear or whether a new crankshaft gear attachment bolt or lockplate was installed.