NTSB Identification: CHI06LA072.
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Accident occurred Tuesday, January 24, 2006 in Jackson, MI
Probable Cause Approval Date: 03/26/2007
Aircraft: Piper PA-32-260, registration: N3946W
Injuries: 1 Serious.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The airplane was substantially damaged when it struck trees and terrain during a forced landing following a loss of engine power. The pilot reported that he obtained a weather update and that the weather consisted of light snow, and forecast icing conditions below 10,000 feet. He also stated that the "potential icing conditions did not suggest the flight could not be safely conducted." About 20 minutes into the flight, while at cruise power and approximately 7,000 feet, the airplane began to lose manifold pressure and the engine began to sputter. He was " losing power, losing airspeed and losing altitude." The pilot applied full carburetor heat but the loss of engine power persisted. He subsequently executed a forced landing in a wooded area and he could not find a clearing during the forced landing attempt. During subsequent examination of the airplane, the right magneto would not produce spark. Disassembly revealed that the contact point would open and close when the magneto was rotated. The spark plugs were black and sooty. The air filter element was found to be wet and water could be wrung from it. Water was also in the filter housing. The carburetor heat control was found in the off position. A Federal Aviation Administration Advisory Circular (AC) stated that impact ice forms when moisture-laden air at temperatures below freezing strikes and freezes on parts of the airplane. The AC further stated that pilots should be particularly alert for such icing when flying in snow, sleet, rain, or clouds and that it is usually preferable to use carburetor heat or alternate air as an ice prevention means, rather than as a deicer, because fast forming ice which is not immediately recognized by the pilot may significantly lower the amount of heat available from the carburetor heating system. The weather conditions at the airport nearest the accident site included light snow, freezing fog, a temperature of -1 degree Celsius, and a dew point of -3 degrees Celsius.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: the blocked induction air filter due to ice accumulation which resulted in a loss of engine power. The pilot's improper weather evaluation, trees, snow, fog, and icing conditions were factors. Full narrative available
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