Casualties unknown

Loss of Engine Power During Swath Run Due to Maintenance Error (N9957J)

Austin, MN, US

On July 6, 1998, a Cessna T188C (registration N9957J) was involved in an aviation accident near Austin, MN. Investigators recorded the probable cause as: Failure to properly secure the throttle control due to a missing cotter pin after maintenance. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 2026-06-10Data APIEditorial standards

A light aircraft experienced a sudden loss of engine power during an agricultural swath run. The pilot was forced to land in unsuitable terrain after the throttle control had been improperly secured by a mechanic earlier that day.

What happened

The incident occurred while the aircraft was conducting an agricultural swath run. During this phase of operation, the engine suffered a sudden and complete loss of power. At an altitude of approximately 80 feet above the ground, the pilot attempted to initiate a forced landing but was unable to avoid unsuitable terrain.

The investigation

Post-accident inspection revealed that a cotter pin had been left out of the throttle control assembly. This omission occurred during maintenance performed earlier on the same day as the accident. A mechanic involved in the service stated that he had disassembled the component but failed to safety it properly before reassembly.

Findings

The primary contributing factor was the failure to install a critical retaining pin during routine maintenance. This mechanical oversight directly led to the throttle control becoming unsecured, resulting in the loss of engine power during critical flight operations.

Probable cause

Failure to properly secure the throttle control due to a missing cotter pin after maintenance.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001211X10494. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.