N552ESCessna Aircraft 162 · 2013

On September 28, 2017, about 1648 eastern daylight time, a Cessna 162, 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 the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed for the local flight that departed Huntsville Executive Airport (MDQ), Huntsville, Alabama.The flight instructor stated the preflight inspection, engine start, and taxi were normal. While returning to the airport they began an 80-knot descent from 3,000 ft 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 of the airplane and pumped the throttle which resulted in a brief surge of power, but did not restore full power to the engine. He performed a forced landing to a field, and after touchdown the airplane impacted trees.

The two-seat, high-wing airplane was manufactured in 2013 and was equipped with a Continental O-200 series, 100-horsepower reciprocating engine. Its most recent 100-hour inspection was completed November 4, 2016.

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 Federal Aviation Administration (FAA) third-class medical certificate was issued on June 23, 2017. He reported 3,463 total hours of flight experience, of which 11 were in the accident airplane make and model.

Examination of the airplane after the accident by an FAA inspector revealed substantial damage 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 on the airframe utilizing the airplane's own battery and fuel system. The engine started and ran continuously at multiple power settings without interruption. A second engine test run was performed by the NTSB. The engine started immediately, accelerated smoothly, and ran continuously at multiple power settings without interruption. No evidence of any pre-impact mechanical malfunctions or failures of the engine was noted.

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 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, which measured the temperature at the throat of the carburetor. He stated the temperature did not drop below 72° F.

The Cessna 162 Pilot Operating Handbook (POH) states, "The G3000 CARB °F indicator provides advisory information but does not replace the need to monitor engine condition and adjust carburetor heat or mixture as needed for safe engine performance." The POH further states that during descent, "Carburetor heat should be used as needed for engine roughness and applied before reducing power to prevent carburetor ice from forming during low power descent."

The carburetor temperature indicator "tape display range is from 20 to 80°F and the digital indication range is from -40°F to 100°F. A yellow caution range is depicted from 5°F to 40°F." A note states, "Although carburetor ice is more likely to form at temperatures within the yellow band range, it can form at temperatures outside the yellow caution range. If engine roughness or unexplained RPM loss is encountered, full carburetor heat should be immediately applied."

According to the FAA Pilot's Handbook of Aeronautical Knowledge, carburetor ice occurs due to the effect of fuel vaporization and the decrease in air pressure in the carburetor's venturi, which can cause a sharp temperature decrease in the carburetor. If water vapor in the air condenses when the carburetor temperature is at or below freezing, ice may form on the internal surfaces of the carburetor, including the throttle valve. This then restricts the flow of the fuel/air mixture and reduces engine power. Generally, the first indication of carburetor icing in an airplane with a fixed-pitch propeller is a decrease in engine rpm, which may be followed by engine roughness. Under certain conditions, carburetor ice can build unnoticed until power is added.

The handbook further described that carburetor heat is an anti-icing system that preheats the air before it reaches the carburetor, and is intended to keep the fuel/air mixture above the freezing temperature to prevent the formation of carburetor ice. Carburetor heat can be used to melt ice that has already formed in the carburetor if the accumulation is not too great, but using carburetor heat as a preventative measure is the better option.