Casualties unknown

1987-07-20: Ayres 600S-2D (N4436F) — Farmers Flying Service — Bancroft, WI

Bancroft, WI, US

On July 20, 1987, an Ayres 600S-2D (registration N4436F) operated by Farmers Flying Service was involved in an aviation accident near Bancroft, WI. Investigators recorded the probable cause as: The pilot's failure to maintain directional control during landing, which was related to an axle spacer on the right wheel that was worn beyond limits and prevented the wheel from turning. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 2 related events involving the same aircraft type or operator are linked below.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 1781061362Data APIEditorial standards

Aircraft veered right upon landing and struck a fence post, causing substantial damage. Investigation revealed the right wheel axle spacer was worn beyond limits.

What happened

During the landing phase of flight, the aircraft deviated significantly to the right after touching down. The pilot attempted to correct the trajectory by applying left brake pressure and left rudder input; however, these control inputs failed to arrest the turn. Consequently, the aircraft continued its path off the runway surface and impacted a fence post. This collision resulted in substantial damage to the airframe.

The investigation

A subsequent mechanical examination of the aircraft was conducted to determine the root cause of the loss of directional control. Inspectors focused on the landing gear assembly, specifically the right main wheel. The inspection revealed that the axle spacer located on the right wheel had worn beyond its operational limits. This excessive wear prevented the wheel from rotating freely.

Findings

The investigation determined that the primary factor contributing to the accident was the mechanical failure of the landing gear component. Specifically:

  • The axle spacer on the right wheel was worn beyond limits.
  • This condition prevented the right wheel from turning during the landing roll.
  • The lack of rotation on one side contributed to the uncontrolled veer to the right.

The pilot's application of corrective controls was insufficient to counteract the asymmetric drag caused by the non-rotating wheel. The resulting impact with the fence post led to substantial damage to the aircraft.

Probable cause

The pilot's failure to maintain directional control during landing, which was related to an axle spacer on the right wheel that was worn beyond limits and prevented the wheel from turning.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001213X31425. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.