HAMILTON, MT, USA
N71654
CESSNA 182M
AFTER ABOUT 15 MIN OF FLIGHT, THE PILOT DESCENDED FROM HIS CRUISE ALTITUDE OF 6,000 FT MSL TO 4,600 FT MSL PRIOR TO ENTERING THE TRAFFIC PATTERN. HE EXECUTED A 360 FOR SPACING, ENTERED DOWNWIND, AND PERFORMED HIS PRE-LANDING CHECKLIST. ACCORDING TO THE PILOT, HE DID NOT APPLY CARBURETOR HEAT UNTIL HE WAS ESTABLISHED ON FINAL AND HAD SELECTED FULL FLAPS, REDUCED POWER TO 15 IN MP, AND ADVANCED THE PROPELLER FULL FORWARD. WHEN THE CARBURETOR HEAT WAS SUPPLIED, THE ENGINE EXPERIENCED A 'SEVERE/SIGNIFICANT' POWER LOSS. THE AIRPLANE TOUCHED DOWN HARD IN SOFT TERRAIN SHORT OF THE RUNWAY AND FLIPPED OVER. THE OWNERS MANUAL 'LET-DOWN' CHECKLIST CALLS FOR CARBURETOR HEAT TO BE APPLIED 'IF ICING CONDITIONS EXIST.' IN THE EXISTING WEATHER CONDITIONS, SEVERE CARBURETOR ICING COULD OCCUR AT GLIDE POWER.
On April 7, 1993, at approximately 1915 mountain daylight time (MDT), a Cessna 182M, N71654, flipped over during an attempted emergency landing about 200 feet short of the runway at Ravalli County Airport, Hamilton, Montana. The FAA certificated private pilot, who was the sole occupant of the aircraft, received minor injuries, and the aircraft sustained substantial damage. The personal pleasure flight, which had departed Missoula, Montana, approximately 15 minutes earlier, was operating in visual meteorological conditions at the time of the accident. The pilot had not filed a flight plan, and there was no report of an ELT activation. The pilot stated that he descended from his cruise altitude of 6,000 feet to 4,600 feet Mean Sea Level (MSL), prior to entering the pattern. He then executed a 360 degree turn for spacing, entered the downwind, and performed his pre landing checklist. He made a power reduction, flap position change, and RPM adjustment prior to turning final. According to the pilot, he did not apply carburetor heat until after he was established on final approach and had selected full flaps, reduced the power to 15 inches of manifold pressure, and advanced the propeller to full froward. Then, when carburetor heat was applied, the engine experienced a "severe"/"significant" power loss. The pilot then advanced the throttle to the full forward position in an attempt to correct the loss of power. When this did not work, the pilot pulled the power to full idle, and then advanced the throttle one half inch forward. The pilot said that with the throttle at that position, he turned the ignition switch to the "off" position, then to the "on" position, and finally to "both." These actions did not restore power, and therefore the pilot elected to attempt a forced landing short of the runway. He said that during the attempted forced landing, his airspeed got low, the aircraft descended very steeply, and then touched down hard on the soft terrain. After the hard touchdown, the aircraft flipped over, coming to rest in the inverted position. In a telephone conversation after the accident, the pilot was advised that the "Let-Down" checklist, from the Owner's Manual for the year in which this aircraft was manufactured, calls for carburetor heat to be applied "if icing conditions exist." He was also advised that according to the FAA/DOT Carburetor Icing Probability Chart, he was flying in conditions where carburetor icing may occur at both glide and cruise power, and where "severe icing" may occur at glide power. The pilot responded to this information by saying, he had not been made familiar with any charts that showed conditions under which carburetor icing may occur, and he had made the decision to delay application of carburetor heat until established on final, based upon the fact that he had not observed any visible moisture in the air. After the accident, the aircraft was checked by an FAA Airworthiness Inspector, and no evidence of pre impact malfunction or discrepancies was found. The engine was then run at various power settings, and no loss of power was experienced.
THE PILOT'S IMPROPER USE OF CARBURETOR HEAT. A FACTOR WHICH CONTRIBUTED TO THE ACCIDENT WAS THE CARBURETOR ICING CONDITIONS.
Source: NTSB Aviation Accident Database
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