History of Flight
On September 22, 2012, at 2127 eastern daylight time, a Cessna 182Q, N735FJ, was substantially damaged when it impacted trees and terrain during a forced landing in Fort Thomas, Kentucky. The private pilot and the passenger sustained minor injuries. Night visual meteorological conditions prevailed, and no flight plan was filed for the local flight that originated at Cincinnati Municipal Airport-Lunken Field (LUK), Cincinnati, Ohio. The personal flight was conducted under 14 Code of Federal Regulations Part 91.
According to the pilot, he arrived at LUK about 2000. He described the evening as "a beautiful ¼ moon-lit and starry evening" with winds having calmed to 6-8 knots at 350 degrees. He performed a "complete" exterior and interior preflight inspection, noting 12 quarts of oil and fuel quantities of 25 gallons in the left tank and 27 gallons in the right tank. After start-up and pre-taxi procedures, he confirmed proper operation of both magnetos, prop pitch, and carburetor heat checks at run-up and idle. The airplane took off from runway 3R about 2040.
During climb to 3,000 feet mean sea level, the pilot noticed the carburetor heat gauge was not rising. He tapped the glass and it stayed to the left; he made a mental note to tell his mechanic. He had previously noticed that on mild days the carburetor heat needle barely entered the green, which he attributed to the overhauled engine. After takeoff, he applied carburetor heat for 5-minute intervals when changing tanks every 20 minutes.
The pilot cut the flight short due to light rain shown on his onboard weather display. He requested and received permission to descend from 3,000 to 2,500 feet for an extended right base to runway 3R. He applied full carburetor heat and began descent procedures. About 6 nautical miles from the runway, he felt a "power drop." The engine continued running but the airplane descended faster than anticipated. Applying more throttle gave a slight boost but not enough. He advised the tower of the power loss. As the airplane descended toward wooded hills, he recalled the Hudson River tail-first landing and executed a pronounced flare, with the stall warning activating. The airplane struck the canopy in a belly-first attitude at about 55 knots.
During a postflight interview, the pilot confirmed that the carburetor temperature gauge had been to the far left since the beginning of the flight, indicating severe carburetor icing, but he thought the gauge was faulty.
Meteorological Information
Weather recorded at LUK at 2053 included calm winds, a temperature of 12°C (54°F), and a dew point of -1°C (30°F). The FAA chart "Conditions Favoring Carb Ice Formation" indicated the probability of serious carburetor icing at glide power under those conditions. Temperature and dew point recorded at 2153 were identical.
Pilot Information
The pilot, age 67, held a private pilot certificate with a single-engine land rating. He reported 376 total flight hours, with 116 hours in the make and model. He also owned a Cessna 172.
Aircraft Information
The airplane's Continental O-470-series engine was overhauled and tested on July 25, 2012, and installed at airplane total time 4,735.0 hours. A logbook entry dated August 28, 2012, at 4,736.0 hours noted that the carburetor was removed, repaired, reinstalled, and "run up ok for return to service." The owner of the maintenance facility stated that the carburetor was returned to the manufacturer for overhaul whenever an engine was overhauled. The airplane was equipped with a carburetor temperature gauge with arcs: black from -50°C to -10°C, yellow from -10°C to +10°C, and black from +10°C to +50°C.
According to the Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25A), if air temperature and moisture content are such that carburetor icing is improbable, the engine can operate with the indicator in the yellow range with no adverse effects. If atmospheric conditions are conducive to icing, the indicator must be kept outside the yellow arc by applying carburetor heat.
The Cessna 182Q Pilot Operating Handbook (POH) provides guidance on carburetor heat usage and describes that an unexplained loss in manifold pressure could be caused by carburetor ice or air intake filter ice. For rough engine operation or loss of power due to carburetor icing, the POH recommends applying full throttle and pulling the carburetor heat knob full out until the engine runs smoothly, then removing heat and readjusting throttle.
Wreckage and Impact Information
The responding FAA inspector noted no preexisting mechanical anomalies that would have precluded normal operation. Photographs showed the propeller with no noticeable chordwise scratching and one of two blades bent aft. Another photograph showed the carburetor heat control partially pulled out, the throttle full forward, the propeller pitch full forward, and the mixture pulled out; however, the positions in flight could not be confirmed as the engine had pulled away from the firewall during impact. The NTSB did not take control of the wreckage; it was removed from the woods and later sold. According to the maintenance facility owner, he and engine facility personnel discussed the event but could find no mechanical source of failure given the impact damage.
The pilot provided two photographs and expressed concern that a crimp in the scat tube from the heat manifold to the carburetor may have led to the engine shutdown. However, the pilot did not note any engine anomalies when carburetor heat was applied during cruise flight with higher air flow requirements. He also noted that during the carburetor heat check during engine run-up, the rpm drop was less than he expected from the engine before overhaul.
Research
FAA publications, including the Pilot's Handbook of Aeronautical Knowledge and Special Airworthiness Information Bulletin CE-09-35, address carburetor icing prevention and recognition. The SAIB notes that warning signs include a drop in manifold pressure in constant-speed propeller airplanes and roughness in engine operation. The pilot should respond by applying full carburetor heat immediately. Additional guidance from Advisory Circular FAA-P-8740-24 "Tips on Winter Flying" discusses fuel ice formation and the critical nature of partial throttle (cruise or letdown) for carburetor ice.
Anecdotal research from AOPA Flight Training articles describes scenarios where carburetor ice can form even with heat applied at low power settings, and recommends clearing the engine periodically with power increases.