Aviation Accident Summaries

Aviation Accident Summary ANC06LA043

Iliamna, AK, USA

Aircraft #1

N36291

Taylorcraft BC12-65

Analysis

The certificated private pilot reported that while in cruise flight over an area of snow-covered terrain, he noted a rough running engine and a slight reduction in engine rpm. The application of carburetor heat and engine emergency procedures did not remedy the engine roughness, which was followed by a rapid loss of engine power, and subsequent loss of altitude. The pilot said that he was unable to restore adequate engine power to maintain level flight, and he selected a snow-covered plateau as a forced landing site, which required a downwind approach due to terrain features. Just before touch down on the soft, snow-covered terrain, he said the left wing stalled and struck the ground, causing the airplane to cartwheel to the left. The airplane sustained structural damage to the left wing and fuselage. In the pilot's written report to the NTSB, he stated that weather conditions at the time of the accident were, in part: Visibility, 2 miles; clouds and sky condition, 2,000 feet broken; wind, 090 degrees at 20 knots, gusting to 35 knots; temperature, 20 degrees F, with light snow showers and blowing snow. In the section of the form that inquires about mechanical malfunction/failure, he wrote: "Carb Icing."

Factual Information

On April 3, 2006, about 1000 Alaska daylight time, a wheel-equipped Taylorcraft BC12-65 airplane, N36291, sustained substantial damage during a forced landing following a loss of engine power, about 16 miles northwest of Iliamna, Alaska. The airplane was being operated as a visual flight rules (VFR) cross-country personal flight under Title 14, CFR Part 91, when the accident occurred. The solo private certificated pilot sustained minor injuries. Visual meteorological conditions prevailed, and no flight plan was filed. The flight originated about 0930, from a remote off-airport site about 40 miles southwest of Iliamna, and was en route to Iliamna when the accident occurred. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on April 4, the pilot related that during the flight to Iliamna, weather conditions consisted of ceilings between 600 and 800 feet, along with winds of 25 knots and blowing snow. As the flight progressed towards Iliamna, he noted a rough running engine and a slight reduction in engine rpm. He said that the application of carburetor heat and engine emergency procedures did not remedy the engine roughness, which was followed by a rapid loss of engine power, and subsequent loss of altitude. The pilot said that he was unable to restore adequate engine power to maintain level flight, and he selected a snow-covered plateau as a forced landing site. He said that terrain features around the forced landing site required a downwind approach. Just before touch down on the soft, snow-covered terrain, he said the left wing stalled and struck the ground, causing the airplane to cartwheel to the left. The airplane sustained structural damage to the left wing and fuselage. In the pilot's written report that was submitted along with the NTSB Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2), dated April 25, he reported that weather conditions at the time of the accident were, in part: Visibility, 2 miles; clouds and sky condition, 2,000 feet broken; wind, 090 degrees at 20 knots, gusting to 35 knots; temperature, 20 degrees F, with light snow showers and blowing snow. In the section of the form that inquires about and mechanical malfunction/failure, he wrote: "Carb Icing."

Probable Cause and Findings

The pilot's delayed use of carburetor heat, which resulted in a loss of engine power during cruise, and an in-flight collision with snow-covered terrain. Factors associated with the accident were an unfavorable wind, and the pilot's inadvertent stall of the airplane during the emergency descent.

 

Source: NTSB Aviation Accident Database

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