On March 28, 1991, a Piper PA-24-250 (registration N6044P) operated by Nichols Brothers Boatbuilders was involved in an aviation accident near Chehalis, WA. Investigators recorded the probable cause as: Improper seating of the crankshaft gear during major overhaul due to non-compliance with a service bulletin, resulting in fatigue failure of the crankshaft dowel. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During a cross-country flight, an engine lost power. During the emergency descent, the airplane collided with a building. Post-crash inspection revealed improper seating of the crankshaft gear during overhaul, leading to fatigue failure of the crankshaft dowel. Non-compliance with a service bulletin was identified.
Incident Overview
During a cross-country flight, the engine experienced a loss of power. While executing an emergency descent following the power loss, the airplane collided with a building.
Post-Crash Inspection Findings
A post-crash examination of the engine revealed that the crankshaft gear had not been seated properly during a major overhaul. This improper seating resulted in the fatigue failure of the crankshaft dowel.
Service Bulletin Non-Compliance
Further investigation into the engine overhaul history indicated that a service bulletin was not complied with. The bulletin called for the installation of a crankshaft gear manufactured with three scallops, each measuring three-quarter inch in radius. These scallops are designed to allow for inspection of the gear and crankshaft assembly.
Probable cause
Improper seating of the crankshaft gear during major overhaul due to non-compliance with a service bulletin, resulting in fatigue failure of the crankshaft dowel.
A SkyWalk Join't 3 paraglider crashed into the ground near Las Vizcachas, Chile, on September 1, 2024. The pilot and passenger sustained serious spinal…
PARAPENTE (ULTRALIVIANO NO MOTORIZADO)·2024-09-01DGAC Chile
A Cessna 172N struck electrical cables while on final approach to land at Aucó Aerodrome in Chile. The pilot was uninjured, but the aircraft sustained damage…
A Bombardier DHC-8-402 suffered a tail strike during landing at Puerto Williams on September 9, 2024. All 76 occupants were unharmed, but the aircraft…
A MYD JS-MD 3 glider veered off the runway and struck a wall at Vitacura Aerodrome on January 6, 2025. The pilot was uninjured, but the aircraft sustained…
A recreational paraglider flight in Puchuncaví, Chile, ended with the pilot sustaining serious injuries after a rapid descent and impact with a hillside on…
PARAPENTE (ULTRALIVIANO NO MOTORIZADO)·2025-03-29DGAC Chile
A Tecnam P2006T landed on its belly at an aerodrome in Poland after the crew failed to confirm landing gear deployment. The incident resulted in no injuries…