Accident Overview
On May 23, 2012, at approximately 1340 Pacific daylight time, a Cessna 150L (registration N11428) experienced a partial loss of engine power while maneuvering in the local area near Tulare, California. The student pilot, who was also the registered owner, was operating the airplane under Part 91 of the Federal Aviation Regulations. The student pilot and one passenger were not injured. The airplane sustained substantial damage. The flight had departed from Mefford Field Airport in Tulare about 1300. Visual meteorological conditions prevailed, and no flight plan was filed.
Flight Details
According to the student pilot, after departure he was maneuvering the airplane at an altitude of about 1,300 feet above ground level when the engine began to sputter. He configured the airplane for a forced landing in an alfalfa field below. During the landing rollout, the airplane encountered a water-filled ditch. The airplane nosed over inverted, resulting in damage to the tail section.
Aircraft Information
A review of the airplane’s logbooks revealed that it had undergone an annual inspection on October 12, 2011, at a total time of 3,238 hours. The student pilot reported that he had prior problems with the carburetor and thought that may have contributed to the sputtering engine. Following the accident, the airplane was sold to the student pilot’s past certified flight instructor (CFI). The CFI reported that he inspected the fuel tanks and found them clear and free of debris. The engine had no evidence of catastrophic mechanical malfunction or failure. The CFI removed the carburetor and did not find any anomalies that would have precluded normal operation.
Weather Conditions
A routine aviation weather report (METAR) generated by an Automated Surface Observation System (ASOS) at Visalia Municipal Airport, located about 10 nautical miles southwest of the accident site, indicated that about 5 minutes prior to the accident the wind was variable from 320 to 020 degrees at 11 knots with gusts to 17 knots. The temperature was 79 degrees Fahrenheit, the dew point was 48 degrees Fahrenheit, and the altimeter setting was 29.89 inches of mercury.
Carburetor Ice Information
The FAA published Special Airworthiness Information Bulletin (SAIB) CE-09-35 in June 2009 regarding carburetor ice prevention. The SAIB noted that carburetor icing does not just occur in freezing conditions; it can occur at temperatures well above freezing when there is visible moisture or high humidity. Vaporization of fuel combined with the expansion of air as it flows through the carburetor (the venturi effect) causes sudden cooling, and a significant amount of ice can build up within a fraction of a second. The SAIB contained a graph illustrating the probability of carburetor icing for various temperatures, dew points, and relative humidity conditions. According to the SAIB, a pilot encountering the ambient conditions reported by the Visalia METAR could expect serious carburetor icing while at glide power.