Casualties unknown

1995-06-21: Air Tractor AT-401 (N4537L) — Hearne, TX

Hearne, TX, US

On June 21, 1995, an Air Tractor AT-401 (registration N4537L) was involved in an aviation accident near Hearne, TX. Investigators recorded the probable cause as: The failure of the number two cylinder, which resulted in a loss of engine power during takeoff climb. 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 agricultural aircraft experienced an in-flight engine failure during takeoff, resulting in a forced landing and loss of control due to restricted visibility from oil on the windshield.

What happened

The incident occurred during the initial climb phase after takeoff from an agricultural airstrip. The pilot reported that the engine suddenly lost power while ascending. At the same time, the pilot's forward vision was significantly impaired because oil had covered the aircraft's windshield, likely due to a leak or breach in the engine system.

Attempting to manage the emergency, the pilot executed a forced landing into an adjacent cotton field. The approach and touchdown were uncontrolled; the aircraft impacted the ground with excessive force. Upon impact, the pilot lost control of the airplane, leading to substantial damage to the airframe and its systems.

The investigation

Following the accident, the operator conducted a post-accident examination of the aircraft's powerplant to determine the root cause of the sudden power loss. The inspection focused on the engine components to identify any mechanical failures that could explain the in-flight shutdown.

The technical review revealed that the loss of engine power was directly caused by a structural failure within the engine block. Specifically, the examination confirmed that the number two cylinder had failed. This mechanical breakdown prevented the engine from generating sufficient thrust to maintain flight during the critical climb phase.

Findings

Several factors contributed to the severity of the accident. The primary mechanical issue was the failure of the number two cylinder, which initiated the chain of events leading to the emergency landing. Additionally, the presence of oil on the windshield created a hazardous visual environment for the pilot during the critical moments of engine failure and subsequent forced landing.

The combination of sudden power loss and restricted visibility made it difficult for the pilot to execute a controlled descent. The result was a hard landing in the cotton field where control was lost upon impact. This sequence highlights the risks associated with mechanical failures in agricultural aviation operations, particularly when compounded by environmental factors like oil leaks affecting cockpit visibility.

Safety message

This incident underscores the importance of regular engine maintenance and inspection to prevent catastrophic component failures such as cylinder fractures. It also highlights the need for effective sealing systems to prevent oil leaks that can obscure pilot vision during critical flight phases.

Probable cause

The failure of the number two cylinder, which resulted in a loss of engine power during takeoff climb.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001207X03715. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.