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Casualties unknown

1994-06-20: Hughes 269C (N7404F) — U. S. Dept. OF Agriculture — London, TX

London, TX, US

On June 20, 1994, a Hughes 269C (registration N7404F) operated by U. S. Dept. OF Agriculture was involved in an aviation accident near London, TX. Investigators recorded the probable cause as: THE PARTIAL POWER LOSS DUE TO A STICKING VALVE. FACTORS WERE THE REMAINING WORN LOBES ON THE CAMSHAFT AND THE LACK OF SUITABLE TERRAIN ONTO WHICH A SUCCESSFUL FORCED LANDING COULD BE EXECUTED. 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 coyote eradication flight, the aircraft experienced partial power loss with decreasing RPM and needle split. While maneuvering at low altitude, the main rotor blades struck trees and the aircraft rolled right, impacting the ground. Investigation found worn camshaft lobes and a heat-discolored, sticking exhaust valve.

Background

The accident occurred during a coyote eradication flight. The aircraft was operating at low altitude and airspeed while the pilot maneuvered for the mission.

Accident Sequence

According to the pilot, while maneuvering, he felt a vibration through the airframe. The engine and main rotor RPM began to decrease, and the needles split. He applied full power, but the engine would only develop 2,000 RPM. While the pilot was maneuvering to a clear area, the main rotor blades struck trees. The aircraft then rolled to the right and impacted the ground.

Investigation Findings

Following the accident, the engine was test run in the airframe and found to be running rough. Investigation revealed that the engine camshaft lobes were worn beyond limits. Additionally, the #4 exhaust valve was heat discolored and showed signs of sticking.

Engine failure

More accident analyses

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001206X01521. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.