Engine power loss and crash of N9496D on dirt strip

Casualties unknown • Winston, NM, US

An aircraft crashed on rocky terrain following an engine power loss shortly after takeoff from a high-altitude dirt runway.

What happened

The pilot took off from Runway 30, which is a high-altitude dirt strip featuring a 3.8% uphill gradient. During the takeoff roll, the pilot leaned the mixture. Winds at the time were from the north-northwest at approximately 14 knots.

While the aircraft was between 200 and 300 feet above ground level, the engine began to lose power. As the pilot attempted to avoid trees, the aircraft settled and crashed into rocky terrain. A fire subsequently consumed the N9496D.

The investigation

An examination of the Marvel-Schebler MA4-SPA carburetor revealed several mechanical issues. The unit contained a deteriorated composite float, and part of the float toe was missing. Additionally, the needle valve was stuck, and both the valve and seat were covered with a soft, sticky substance. The investigation also found that the inlet filter screen was almost entirely blocked by foreign debris. It was noted that an STC had been issued for N9496D allowing for the use of automobile fuel.

Probable cause

The engine lost power due to a stuck needle valve and a blocked inlet filter screen caused by foreign debris and a deteriorated carburetor float.

Frequently asked questions

What happened in the 1989-09-12 Piper PA-18A-150 accident near Winston, NM?

An aircraft crashed on rocky terrain following an engine power loss shortly after takeoff from a high-altitude dirt runway.

What aircraft was involved and where did it happen?

The accident on 1989-09-12 involved a Piper PA-18A-150, registration N9496D, at Winston, NM.

What was the probable cause of the accident?

The engine lost power due to a stuck needle valve and a blocked inlet filter screen caused by foreign debris and a deteriorated carburetor float.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001213X29352. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.

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