On March 7, 1989, a Stinson 108-2 (registration N150C) was involved in an aviation accident near Custer, SD. Investigators recorded the probable cause as: The pilot's installation of both magnetos without cotter pins on the drive gear retaining nuts, which allowed the nuts to back off, disconnecting the magnetos and allowing one gear to fall into the engine, resulting in engine stoppage. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A private pilot experienced engine failure during climb out after installing magnetos without cotter pins. Attempted landing on a gravel driveway resulted in gear collapse and slide.
Incident Details
A private pilot was performing a flight following the installation of two magnetos. According to a witness and the pilot, the engine quit during climb out. The pilot reported hearing something break inside the engine. Subsequently, the pilot attempted to land on a gravel driveway located south of the runway. Upon impact, the main landing gear collapsed. The airplane came to rest after sliding approximately 150 feet.
Post-Accident Findings
A post-accident inspection revealed that both magnetos had been installed without cotter pins on the drive gear retaining nuts. This omission allowed the nuts to back off during operation, which disconnected the magnetos. Additionally, one of the drive gears fell into the engine, leading to the reported engine stoppage.
Probable cause
The pilot's installation of both magnetos without cotter pins on the drive gear retaining nuts, which allowed the nuts to back off, disconnecting the magnetos and allowing one gear to fall into the engine, resulting in engine stoppage.
What happened in the 7 Mar 1989 Stinson 108-2 accident near Custer, SD?
A private pilot experienced engine failure during climb out after installing magnetos without cotter pins. Attempted landing on a gravel driveway resulted in gear collapse and slide.
What aircraft was involved and where did it happen?
The accident on 7 Mar 1989 involved a Stinson 108-2, registration N150C, at Custer, SD.
What was the probable cause of the accident?
The pilot's installation of both magnetos without cotter pins on the drive gear retaining nuts, which allowed the nuts to back off, disconnecting the magnetos and allowing one gear to fall into the engine, resulting in engine stoppage.
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…