Event Overview
On September 28, 2017, at about 1648 eastern daylight time, a Cessna 162, registration N552ES, was substantially damaged during a forced landing following a total loss of engine power near Huntsville, Alabama. The flight instructor and student pilot were not injured. The instructional flight was conducted under 14 Code of Federal Regulations Part 91 in visual meteorological conditions without a flight plan. The flight had departed from Huntsville Executive Airport (MDQ), Huntsville, Alabama.
Pilot and Aircraft Information
The flight instructor held airline transport pilot and flight instructor certificates with ratings for airplane single and multiengine land, rotorcraft/helicopter, and glider. His most recent FAA third-class medical certificate was issued on June 23, 2017. He reported 3,463 total hours of flight experience, with 11 hours in the accident airplane make and model.
The two-seat, high-wing airplane was manufactured in 2013 and equipped with a Continental O-200 series, 100-horsepower reciprocating engine. Its most recent 100-hour inspection was completed November 4, 2016.
Flight Sequence
The flight instructor stated that the preflight inspection, engine start, and taxi were normal. While returning to the airport, they began an 80-knot descent from 3,000 feet mean sea level (msl) to traffic pattern altitude. When the student increased engine power to level off around 1,400 ft msl, the engine died instantly. The flight instructor took control and pumped the throttle, resulting in a brief surge of power, but did not restore full power. He performed a forced landing to a field; after touchdown, the airplane impacted trees.
Post-Accident Examination
An FAA inspector examined the airplane after the accident. Substantial damage was found to the left wing and aileron, right wingtip, and fuselage. The airframe fuel strainer, drain bowls, and engine fuel system components were absent of water, debris, or contamination, and contained fluid consistent with 100LL aviation fuel. The inspector attempted an engine start using the airplane's battery and fuel system; the engine started and ran continuously at multiple power settings without interruption. A second engine test run by the NTSB also resulted in immediate start, smooth acceleration, and continuous operation at multiple power settings. No evidence of pre-impact mechanical malfunctions or failures of the engine was noted.
Weather and Carburetor Icing Conditions
At 1635, the weather reported at MDQ, about 2 miles south of the accident site, included wind from 100° at 7 knots, visibility 10 statute miles, clear skies, temperature 28°C, dew point 15°C, and altimeter 29.98 inches of mercury. An FAA carburetor icing probability chart indicated that the temperature and dew point conditions were conducive to the formation of serious icing at glide power. Carburetor heat was not used during the descent. The pilot stated the airplane was equipped with a carburetor heat indicator measuring temperature at the throat of the carburetor; the temperature did not drop below 72°F.
Pilot Operating Handbook Guidance
The Cessna 162 Pilot Operating Handbook (POH) states that the G3000 CARB °F indicator provides advisory information but does not replace the need to monitor engine condition. It further states that during descent, carburetor heat should be used as needed for engine roughness and applied before reducing power to prevent carburetor ice. The carburetor temperature indicator has a tape display range from 20 to 80°F and digital indication from -40°F to 100°F, with a yellow caution range from 5°F to 40°F. A note states that although carburetor ice is more likely at temperatures within the yellow band, it can form outside that range, and if engine roughness or unexplained RPM loss is encountered, full carburetor heat should be immediately applied.
General Carburetor Icing Information
According to the FAA Pilot's Handbook of Aeronautical Knowledge, carburetor ice results from fuel vaporization and decreased air pressure in the venturi, causing a sharp temperature decrease. If water vapor condenses when the carburetor temperature is at or below freezing, ice may form on internal surfaces, restricting fuel/air mixture flow and reducing power. The first indication in a fixed-pitch propeller airplane is usually a decrease in rpm, possibly followed by engine roughness. Carburetor heat preheats air to prevent ice formation and can melt existing ice if accumulation is not too great.