Accident Summary
On October 23, 2022, at about 1700 eastern daylight time, a Piper PA28-235, registration N8580N, sustained substantial damage during a forced landing near the Spartanburg Downtown Memorial Airport (SPA) in Spartanburg, South Carolina. The private pilot and three passengers were not injured. The flight was conducted under 14 CFR Part 91 as a personal flight.
The pilot reported a routine preflight, run-up, and takeoff. During initial climb at approximately 600 ft above ground level, a loud noise was heard, the engine rpm dropped to zero, and power was completely lost. The pilot established best glide speed and performed a forced landing onto a city street. On final approach, the airplane struck powerlines but touched down without further incident. After landing, the pilot exited and used a fire extinguisher on smoke coming from the engine area. The powerline strike caused substantial damage to the rudder.
Examination Findings
Examination of the engine revealed no visible impact damage, but sooting and thermal damage were present on the engine, cowling, and accessories. One propeller blade tip had black marks and evidence of melting and erosion, consistent with arc damage.
Valvetrain continuity was established with the camshaft, but crankshaft continuity was not observed. The accessory section was removed, revealing the crankshaft gear partially separated from the crankshaft. The crankshaft gear bolt was partially backed out, with a few stripped threads; the safety clip remained attached. The crankshaft alignment dowel pin had sheared.
The right magneto produced spark on all leads when rotated. The left magneto had a fractured casing, was partially rotated, and had a bent drive shaft; its idler gear was missing teeth.
Metallurgical examination of the left magneto, idler gears, and crankshaft gear components was conducted. The left magneto's internal components showed rotational damage but rotated freely after disassembly. Fracture surfaces on the left magneto gear tooth and left idler gear were consistent with overstress separation. The crankshaft drive gear bolt was bent near the threads, with flattened threads and a smeared end face. The dowel pin fracture was consistent with shear overstress separation.
Maintenance History
The most recent annual inspection was on February 15, 2022, with 34 hours flown since. Maintenance records from January 2, 2021, noted compliance with Airworthiness Directive (AD) 2004-10-14 for propeller strikes as part of a 100-hour inspection. The mechanic who performed it reported no awareness of a propeller strike and stated it was his normal practice to record AD compliance without performing work on the crankshaft gear bolt.
A July 6, 2015 annual inspection also noted AD 2004-10-14 compliance but did not specify inspection or replacement of crankshaft gear components. The left and right magnetos were replaced on December 17, 2015.
The engine was last overhauled on May 2, 2003, about 1,569 hours before the accident. Mandatory Service Bulletin (SB) 475C, issued in January 2003, addressed crankshaft gear modification and assembly procedures and applied to the accident engine. The overhaul endorsement stated all applicable service bulletins were complied, but SB 475C was not specifically referenced. The pilot, who owned the airplane since 2015, reported no knowledge of any prior propeller strikes.
SB 475C stated that damage to the crankshaft gear, counterbored recess, or gear alignment dowels results from improper assembly or reuse of worn parts, and that failure of these components could cause complete engine stoppage.