ANCHORAGE, AK, USA
N7755H
PIPER PA-12
THE PILOT DEPARTED FROM THE PRIVATE AIRSTRIP AFTER A SUCCESSFUL ENGINE RUN-UP. DURING THE CLIMB, AT ABOUT 700 FEET ABOVE THE GROUND, THE ENGINE LOST PARTIAL POWER. THE PILOT ATTEMPTED A FORCED LANDING BUT MISJUDGED HIS APPROACH AND THE AIRPLANE STALLED AS HE OVERSHOT THE FAR END OF THE RUNWAY. THE AIRPLANE IMPACTED TERRAIN AND WAS SUBSTANTIALLY DAMAGED. THE ACCIDENT FLIGHT WAS THE AIRPLANE'S FIRST FLIGHT AFTER THE ENGINE HAD BEEN REBUILT. A DETAILED EXAMINATION OF THE ENGINE AND FUEL SYSTEM DID NOT REVEAL EVIDENCE OF MALFUNCTION. ACCORDING FAA CARBURETOR ICING PROBABILITY CHARTS, THE PREVAILING WEATHER CONDITIONS AT THE TIME OF THE ACCIDENT COULD PRODUCE 'SERIOUS' CARBURETOR ICING AT CRUISE POWER. THE PILOT STATED THAT HE APPLIED CARBURETOR HEAT AT THE TIME OF THE LOSS OF POWER, WITH NO EFFECT.
On July 21, 1995, about 1555 Alaska daylight time, N7755H, a Piper PA-12, collided with terrain during a forced landing in Anchorage and was substantially damaged. The forced landing was precipitated by a partial loss of engine power while the airplane was maneuvering. The private pilot received minor injuries and the sole passenger received serious injuries. Visual meteorological conditions prevailed and no flight plan had been filed. The personal flight was conducted under 14 CFR 91. The pilot stated that the accident flight was the first flight since the engine was rebuilt. After a preflight inspection and successful engine run-up, the airplane departed from a private airstrip and maneuvered about 700 feet above the airstrip. The pilot reported that the "engine lost power," but did not stop. The pilot immediately descended and maneuvered to approach the airstrip and land to the north. He overshot the landing strip and purposely stalled the airplane in an effort to avoid colliding with obstructions. The airplane impacted terrain about 200 feet beyond the end of the runway and was substantially damaged. An examination of the engine and fuel system did not reveal evidence of any mechanical deficiencies. The reported temperature and dew point near the time and place of the accident were 59 degrees F and 57 degrees F respectively. According to the Carburetor Icing Probability Chart published by the FAA (attached), the prevailing weather conditions could produce "serious icing at cruise power" in light aircraft piston engines. The pilot stated that he had applied full carburetor heat immediately upon sensing the power loss, with no effect noted. He said the airplane could not maintain altitude, but the engine continued to run.
THE PILOT'S IMPROPER USE OF CARBURETOR HEAT WHICH LED TO CARBURETOR ICING AND A PARTIAL LOSS OF ENGINE POWER. FACTORS CONTRIBUTING TO THE ACCIDENT ARE PREVAILING CARBURETOR ICING CONDITIONS, AND THE PILOT'S FAILURE TO PROPERLY JUDGE THE AIRPLANE'S DISTANCE AND SPEED DURING THE FORCED LANDING.
Source: NTSB Aviation Accident Database
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