On March 11, 1989, a Grumman G-164A (registration N9874) operated by Hartley Flying Service, Inc. was involved in an aviation accident near Stuttgart, AR. Investigators recorded the probable cause as: The shearing of the supercharger shaft, which resulted in the loss of engine power. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During a crop dusting operation, the pilot lost engine power while lining up for a pass. The aircraft stalled and crashed into terrain after the supercharger shaft sheared.
What happened
The pilot reported that during an agricultural application flight, the engine suddenly lost power as he was preparing to execute his first swath run. As the aircraft began to lose altitude and thrust, it descended to approximately telephone pole height before stalling. The pilot was unable to recover control, and the aircraft collided with the terrain at a steep angle.
The investigation
A post-accident examination of the engine revealed that the supercharger shaft had sheared. This mechanical failure directly resulted in the loss of power during the critical phase of flight. Reports indicated that the aircraft was fully loaded with both fuel and dry fertilizer at the time of the incident.
Findings
The primary factor contributing to the accident was the mechanical failure of the supercharger system. The shearing of the shaft caused an immediate and unrecoverable loss of engine power while the aircraft was low to the ground and heavily loaded.
Probable cause
The shearing of the supercharger shaft, which resulted in the loss of engine power.