N4762B

On December 30, 1995, at 1100 Alaska standard time, a wheel equipped Cessna 180 airplane, N4762B, registered to and operated by the pilot, lost engine power and crashed into trees after takeoff from an unimproved takeoff area on the Cosna River located 40 miles southeast of Tanana, Alaska. The personal flight, operating under 14 CFR Part 91, was departing the Cosna River and the destination was Fairbanks, Alaska. No flight plan was filed and visual meteorological conditions prevailed. The commercial certificated pilot, the sole occupant, was not injured and the airplane received substantial damage.

According to the pilot's statement attached to the NTSB Form 6120.1/2, he had to taxi the airplane a distance of 1,500 feet uphill to reach the takeoff area. He taxied with the carburetor heat applied. He said that during his taxi a lot of fine snow and ice crystals were blown up and remained suspended over the takeoff area. After performing an engine runup, he started his takeoff. The airplane reached an altitude of approximately 15 feet when the engine began to produce only partial engine power. The pilot stated he applied carburetor heat again and some power was restored. He had to lower the airplane's nose to maintain flying speed and the airplane crashed into trees.

During an interview between the pilot and a FAA Flight Standards Inspector, the pilot stated that he thought the air intake screen had become clogged with snow and ice during his taxi to the takeoff area.

Subsequent examination of the engine and airplane showed no mechanical defect of the engine or associated airplane systems.

According to information provided in the Cessna 180 owner's manual, under section 3 titled: Operating Details, "The carburetor heat knob should be pushed full in (cold, off) during all ground operations unless heat is absolutely necessary for smooth engine operation. When the knob is pulled out to the heat position, air entering the engine is not filtered." There is no information in the owner's manual concerning the effect of snow and ice on the intake/induction screen during taxi and takeoff.

A review of information on winter flying and winter operations, provided by the FAA, showed no discussion concerning taxiing through blowing snow, suspended snow, or ice crystal, and the effect on induction intake screen icing.