Casualties unknown

2005-02-04: Air Tractor AT-401 (N4530L) — Calexico, CA

Calexico, CA, US

On February 4, 2005, an Air Tractor AT-401 (registration N4530L) was involved in an aviation accident near Calexico, CA. Investigators recorded the probable cause as: a loss of directional control due to a jammed rudder pedal, which prevented the pilot from exercising full rudder control authority. 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

During a crosswind landing, the pilot's right rudder pedal jammed due to the adjustment pin catching on a groove in the hopper, leading to a loss of control and runway excursion.

Accident Sequence

The airplane veered off the runway during landing, collided with a berm, and came to rest in a ditch following a loss of control. While flaring, the pilot encountered a left crosswind and applied right rudder to compensate, but the pedal would not move. After the accident, the pilot realized he was still depressing the right rudder pedal. He observed that the rudder pedal adjusting pin was caught on the aft edge of the hopper. When he relaxed pressure on the pedal, it moved to the left and became free of the hopper.

Post-Accident Examination

A Federal Aviation Administration (FAA) inspector conducted a post-accident examination. The inspector found a groove that the adjusting pin had carved into the side wall of the hopper over time. The groove began at a radius in the hopper wall where the wall turned 90 degrees from a cross-cockpit orientation to a longitudinal direction. When the inspector depressed the rudder pedal, the adjusting pin contacted the groove throughout its travel. Despite this contact, there was no restriction of movement of the rudder pedal. Additionally, a gouge dimensionally identical in shape and size to the pin was observed in the hopper just to the right of where the adjusting pin contacted the groove. No groove or gouge was found on the left side of the hopper.

Findings

The accident resulted from the rudder pedal adjusting pin becoming caught on the aft edge of the hopper during the landing flare. The pre-existing groove in the hopper wall, created by repeated contact with the pin, allowed the pin to become lodged, preventing the pilot from inputting right rudder as needed to counteract the crosswind. The absence of any restriction during the post-accident test indicates that the binding occurred only under specific conditions of pedal position and pressure.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20050215X00191. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.