SEA95LA225

The CFI stated that he pulled the mixture control to idle cut-off to simulate an engine failure. He then closed the throttle and moved the mixture control to full rich, but could not remember using carburetor heat in the descent. According to the student, the airplane descended for 3 to 4 minutes during the simulated emergency. The instructor then attempted to terminate the situation between 100-500 feet agl. The instructor stated that when he attempted to terminate the situation the engine did not respond to power. The airplane then impacted a canal bank and nosed over into the canal. Temperature and dew point values reported both by the pilot and the weather observation facility at Hailey, approximately 28 miles north-northwest, indicated a potential for serious carburetor icing during descent at the time of the accident according to a carburetor ice hazard chart.

On September 26, 1995, approximately 0945 mountain daylight time, a Cessna TR182, N736LT, received substantial damage when it impacted a canal bank and nosed over into a canal following a loss of engine power near Richfield, Idaho. The two occupants, a student pilot (who was also a co-owner of the airplane) and the certificated flight instructor (CFI) pilot-in-command, were not injured. The flight was a local 14 CFR 91 instructional flight originating from Friedman Memorial Airport, Hailey, Idaho. Visual meteorological conditions prevailed and no flight plan had been filed.

In initial interviews with investigators, the CFI reported that during the instructional profile, he pulled the mixture control to idle cut-off to simulate an engine failure. He then pulled the throttle to idle and moved the mixture control to full rich. He could not remember applying carburetor heat for the descent. His subsequent written report of the accident stated: "During a simulated engine emergency at about 6500 MSL the engine did not respond to power at 500 AGL. Impacted a canal bank at near stall [and] nosed over into the canal, upside down." The CFI also indicated in his written report on the accident that the airplane was equipped with a fuel-injected Lycoming LO-540 engine. The FAA representative to the accident indicated that the engine was in fact a carbureted Lycoming O-540-L3C5D engine. A representative from Cessna's product safety department also indicated to the NTSB investigator that the accident aircraft had been manufactured with an O-540-L3C5D engine.

In a follow-up telephone interview with the student on March 1, 1996, the student stated that he believed the instructor had pulled the carburetor heat out but was not certain of this. He stated that to the best of his recollection, the simulated engine failure situation started at 3,000 to 4,000 feet above ground level and lasted 3 to 4 minutes before the instructor attempted to terminate it at an estimated height of 100 to 150 feet above ground level. The student stated that he did not remember the position of the mixture control at the time recovery from the situation was attempted but was "sure it was in."

The 0945 surface observation at Hailey, approximately 28 nautical miles north-northwest of the accident site, indicated a temperature of 44 degrees F (7 degrees C) and a dewpoint of 34 degrees F (1 degree C). The pilot reported in his written accident report that the temperature at the time of the accident was 60 degrees F (16 degrees C); he did not report a dewpoint value. These temperature and dewpoint values were checked against a carburetor icing hazard chart produced by Transport Canada. Entering the chart with the temperature and dewpoint values of the 0945 Hailey surface observation yielded a plot in an area of the chart annotated "Serious icing - any power". Using the pilot's reported temperature and the dewpoint value of the 0945 Hailey observation yielded a plot in an area of the chart labeled "Serious icing - descent power".