N704QJCessna 150M · 1976

On November 13, 2019, at 0015 mountain standard time, a Cessna 150 airplane, N704QJ, was substantially damaged when it was involved in an accident near Marana, Arizona. The private pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

The pilot reported that he recently purchased the airplane, and the accident flight was a familiarization flight. After taking off he conducted some maneuvers before he proceeded to another airport to perform a touch-and-go landing. About 6 miles away from the airport, he reduced the power setting to about 1,900 rpm and started the descent to land; about 1 mile from the airport, he reduced power to 1,500 rpm, and then idle on final approach. He stated that he applied carburetor heat about halfway to reduce its effect on engine performance. During takeoff, the airplane started to shake, and about 1,500 ft above the ground, the engine lost total power. He performed a forced landing to a field; during which the nose landing gear collapsed.

Examination of the engine by a Federal Aviation Administration (FAA) maintenance inspector revealed that the handle for the fuel strainer drain was extended about 1/2 inch. In addition, fuel streaking was found on the belly of the airplane extending from the drain port on the bottom of the cowling. The handle was manipulated by hand and operated normally. Engine compression and internal continuity was confirmed when the propeller was rotated by hand.

A representative from Textron Aviation reported that, when the carburetor heat control is pulled only halfway out, it will produce half the heat than when fully extended.

Weather about the time of the accident indicated a temperature of 14°C and a dewpoint of 0°C. According to FAA Special Airworthiness Information Bulletin (SAIB) CE 09-35, Carburetor Icing Prevention, this temperature/dew point was conducive to the development of icing at glide power settings.

SAIB CE-09-35 stated that:

…pilots should be aware that carburetor icing doesn't just occur in freezing conditions, it can occur at temperatures well above freezing temperatures when there is visible moisture or high humidity. Icing can occur in the carburetor at temperatures above freezing because vaporization of fuel, combined with the expansion of air as it flows through the carburetor, (Venturi Effect) causes sudden cooling, sometimes by a significant amount within a fraction of a second. Carburetor ice can be detected by a drop in rpm in fixed pitch propeller airplanes and a drop in manifold pressure in constant speed propeller airplanes. In both types, usually there will be a roughness in engine operation.