On September 3, 1995, a Cessna 175 (registration N9425B) was involved in an aviation accident near Staples, MN. Investigators recorded the probable cause as: the pilot's delay in the application of carburetor heat, which resulted in carburetor ice, loss of engine power, and a subsequent forced landing in a swampy area. The carburetor icing (weather) condition was a related factor. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During a flight over a swamp, an airplane experienced an engine power loss. The pilot applied carburetor heat and heard an audible indication. The forced landing resulted in the airplane nosing over in two feet of water; the carburetor separated from the engine. No mechanical anomaly was found, but conditions were conducive for carburetor icing.
Incident Overview
A pilot reported that while flying an airplane approximately 1,000 feet above a swamp, the engine lost power. In response, the pilot applied carburetor heat after noticing an audible indication of the power loss. The subsequent forced landing in the swamp resulted in the airplane nosing over in water that was two feet deep.
Post-Occurrence Examination
During the occurrence, the carburetor separated from the engine. However, examination revealed no preaccident or mechanical anomaly that would have prevented the production of power. The ambient temperature was 83 degrees Fahrenheit, and the dew point was 66 degrees Fahrenheit.
Atmospheric Conditions
According to icing probability charts, the atmospheric conditions at the time were conducive for carburetor icing. The combination of temperature and dew point fell within parameters that increase the likelihood of carburetor ice formation.