Casualties unknown

2001-07-28: Air Tractor AT-301 (N4361S) — Edmore, ND

Edmore, ND, US

On July 28, 2001, an Air Tractor AT-301 (registration N4361S) was involved in an aviation accident near Edmore, ND. Investigators recorded the probable cause as: The incorrect installation of the wheel assembly bolts by maintenance personnel resulting in the stripped bolt threads and ultimate failure of the wheel, and directional control not possible by the pilot. A factor was the ditch. 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 1781061362Data APIEditorial standards

An airplane impacted a ditch and nosed over during a road takeoff. Investigation revealed right wheel assembly separation with stripped and fractured bolts, and left wheel over-torqued bolts, with one incorrect bolt installed.

Accident Overview

During a takeoff from a road, the airplane impacted a ditch and nosed over.

Wreckage Examination

Post-accident examination revealed that the right outboard wheel half, right tire, and right tire inner tube had separated from the airframe. No other anomalies that could be associated with a pre-impact condition were found.

Three of the right wheel through bolts were recovered from the accident scene. Two of these bolts had stripped threads, and a third was fractured in the threaded portion.

The left wheel was examined and found intact. However, seven of the through bolts that hold the left wheel halves together were found to have been over-torqued. The torque readings on these bolts ranged from 125 to 175 inch-pounds. The specified torque, as printed on the wheel, is 90 inch-pounds. Two of the remaining bolts on the left wheel were stripped. Additionally, one of the through bolts was a coarse thread bolt, whereas the bolts specified for attaching the wheel halves are AN4 fine thread bolts.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20010801X01584. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.