CHI97LA081

The dual student stated that they were holding in instrument meteorological conditions at 4,000 feet mean sea level (msl) when Minneapolis air route traffic control center (ARTCC) cleared them for the approach. ' We were told overfly the airport at 4,000 feet on the localizer back course and then intercept the ILS. As I left the holding pattern, the engine shook violently for 2 to 3 seconds, followed by complete engine failure. I established a glide and declared an emergency with ARTCC.' The pilots attempted to restart the engine. The airplane broke out of the clouds at approximately 500 feet above the ground and over a forest. The dual student said, 'I looked for the least dense area and headed for that site. We began encountering the trees just as I was attempting to stall the plane. We came to rest in a wooded, swampy area.' Examination of the wreckage revealed no anomalies. According to Department of Transportation/FAA/CT-82/44 Publication: Light Aircraft Piston Engine Carburetor Ice Detector/Warning Device Sensitivity/Effectiveness, June 1982, Carburetor Icing Probability Chart; the temperature (21 degrees Fahrenheit) and dew point (16 degrees Fahrenheit) at the time the airplane lost power places the probability for carburetor icing in the 'icing - glide and cruise power' area of the chart.

On March 7, 1997, at 1740 central standard time (cst), a Piper PA-28-181, N8259M, operated by a commercial pilot, sustained substantial damage when during holding, the airplane's engine lost power. The airplane subsequently impacted the terrain in a wooded area, 7 miles east of Mosinee, Wisconsin. Instrument meteorological conditions (IMC) prevailed at the time of the accident. The instructional flight was being conducted under 14 CFR Part 91. An IFR flight plan was on file. The instructor pilot and dual student reported no injuries. The local flight originated in Green Bay, Wisconsin, at 1620 cst.

In his written statement, the dual student in the left seat of the airplane said that they were given instructions by air traffic control (ATC) to hold at the "Witen" intersection at 4,000 feet mean sea level (msl). "We were in IMC during the holding pattern. We were cleared for the approach at approximately 1735 (cst). We were told overfly the airport at 4,000 feet on the localizer back course and then intercept the ILS. As I left the holding pattern, the engine shook violently for 2 to 3 seconds, followed by complete engine failure. I established a glide and declared an emergency with Minneapolis air route traffic control center." The pilots attempted to restart the engine. The airplane broke out of the clouds at approximately 500 feet above ground level (agl). The pilots found themselves over a forest. The dual student said, "I looked for the least dense area and headed for that site. We began encountering the trees just as I was attempting to stall the plane. We came to rest in a wooded, swampy area."

The instructor pilot stated that as they were leaving the holding pattern, "the power went from 2200 rpm to 900 rpm." He said that they established best glide speed and "pulled carburetor heat and switched tanks." He also said that the engine mixture was "leaned 50 degrees rich of peak EGT."

The Federal Aviation Administration (FAA) inspector who examined the wreckage at the accident site found the airplane resting upright in a wooded swamp. The leading edges of both wings were crushed aft and bent inward. The leading edge of the right wing was also torn open. The engine remained attached to the mounts. The engine mounts were bent 10 degrees right. Both propeller blades were bent aft. The fuselage remained intact. It showed minor dents and wrinkles. The outboard 18 inches of the right horizontal stabilizer was broken off. Both stabilizers were bent upward approximately 20 degrees at the roots. Flight control continuity was confirmed. Examination of the engine at the accident site revealed no anomalies. Examination of the airplane's engine controls and other systems revealed no anomalies.

According to Department of Transportation/FAA/CT-82/44 Publication: Light Aircraft Piston Engine Carburetor Ice Detector/Warning Device Sensitivity/Effectiveness, June 1982, Carburetor Icing Probability Chart; the temperature (21 degrees Fahrenheit) and dew point (16 degrees Fahrenheit) at the time the airplane lost power places the probability for carburetor icing in the "icing - glide and cruise power" area of the chart.