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Casualties unknown

Cessna aircraft nosed over after engine failure at 3500 feet (N5276U)

San Angelo, TX, US

On January 6, 1983, a Cessna 172RG (registration N5276U) operated by John M. Hetland was involved in an aviation accident near San Angelo, TX. Investigators recorded the probable cause as: A failed valve that penetrated the rocker box cover on a cylinder, resulting in engine power loss. 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 2026-06-20Data APIEditorial standards

An aircraft lost power at 3500 feet MSL, forcing the pilot to land in a field with gear down. The plane nosed over upon impact due to a failed valve.

What happened

The aircraft was operating at an altitude of 3500 feet MSL when the engine began to lose power. Recognizing the mechanical issue, the pilot attempted to return toward the departure airport. However, the engine subsequently lost all power completely. With no option for a powered approach, the pilot decided to execute an emergency landing in a plowed field. The landing gear was left down during the descent and touchdown.

The investigation

Following the accident, investigators examined the aircraft's mechanical components to determine the root cause of the failure. A detailed inspection revealed that a valve had failed. This failed component had penetrated the rocker box cover on one of the engine cylinders, leading to the loss of power.

Probable cause

A failed valve that penetrated the rocker box cover on a cylinder, resulting in engine power loss.
Engine failure

Frequently asked questions

What happened in the 6 Jan 1983 Cessna 172RG accident near San Angelo, TX?

An aircraft lost power at 3500 feet MSL, forcing the pilot to land in a field with gear down. The plane nosed over upon impact due to a failed valve.

What aircraft was involved and where did it happen?

The accident on 6 Jan 1983 involved a Cessna 172RG, registration N5276U, operated by John M. Hetland, at San Angelo, TX.

What was the probable cause of the accident?

A failed valve that penetrated the rocker box cover on a cylinder, resulting in engine power loss.

More accident analyses

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001214X41996. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.