Accident Details
On January 19, 2012, at approximately 1455 central standard time, a Cessna 172I, registration N35571, was substantially damaged during a forced landing near Springfield, Tennessee. The certificated commercial pilot was not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight conducted under 14 CFR Part 91. The flight originated from Vermilion Regional Airport (DNV) in Danville, Illinois, around 1215, and was destined for John C. Tune Airport (JWN) in Nashville, Tennessee.
Pilot Actions
According to the pilot's written statement, he departed from Wittman Regional Airport (OSH) in Oshkosh, Wisconsin, and stopped at DNV to refuel. After departure, he climbed to 3,500 feet to remain below a low ceiling of clouds. Several miles north of Springfield, Tennessee, he listened to the JWN automated weather observation and began a cruise descent. About 10 nautical miles north of JWN, while descending through 2,100 feet, he configured the airplane for landing. He reduced engine power to about 1,500 rpm and set the fuel mixture to full rich but did not activate the carburetor heat. The engine then "suddenly acted as though it were starved for fuel." With rising terrain ahead and only about 800 feet above ground, the pilot pumped the throttle, searched for a suitable forced landing area, and activated the emergency locator transmitter. He approached an intended landing field from the east but was high and fast, so he flew north and circled back to set up for a landing to the southwest. He landed on the downward slope of the field at an airspeed around 60 knots. During the rollout, the nose landing gear struck a ditch and the airplane nosed over.
Post-Accident Examination
A Federal Aviation Administration (FAA) inspector examined the wreckage and reported substantial damage to the nose landing gear and firewall. Upon arrival about 1.5 hours after the accident, a strong odor of aviation gasoline was present. First responders recovered about 5 gallons of fuel that had drained from the airplane. A local airframe and powerplant mechanic, who removed the wings for recovery, reported that each wing contained an "ample" quantity of fuel and noted normal function of the gascolator with fuel present. Under NTSB supervision, about 2 ounces of fuel were drained from the carburetor drain plug. An alternate fuel source was plumbed to the right wing root, the right fuel tank was selected, and fuel flowed to the gascolator and carburetor. The engine started immediately and was operated at various power settings between idle and 2,500 rpm for about 5 minutes with no anomalies noted.
Weather Conditions
The weather reported at Nashville International Airport (BNA), about 21 nautical miles southeast of the accident site, at 1453 included winds from 200 degrees at 10 knots, 10 statute miles visibility, few clouds at 15,000 feet, scattered clouds at 25,000 feet, temperature 10 degrees Celsius, dewpoint minus 4 degrees Celsius, and an altimeter setting of 29.97 inches of mercury.
Carburetor Icing Information
According to FAA Special Airworthiness Information Bulletin (SAIB) CE-09-35, dated June 30, 2009, carburetor icing can occur at temperatures above freezing in the presence of visible moisture or high humidity. Vaporization of fuel and expansion of air through the carburetor cause sudden cooling. Applying the surface temperature and dewpoint to the SAIB's probability diagram indicated that "Icing (glide and cruise power)" conditions prevailed at the time of the accident. The SAIB recommended that pilots use carburetor heat on approach and descent when operating at low power settings or in conditions where carburetor icing is probable.