NTSB Identification: DEN99LA062.
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Accident occurred Thursday, April 01, 1999 in PAYSON, UT
Probable Cause Approval Date: 05/08/2001
Aircraft: Sly RV-6A, registration: N80287
Injuries: 2 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
After being airborne for 15 minutes, the aircraft's engine began to lose power. The pilot initiated an emergency landing along a county road but switched to another road to avoid power lines. Upon touchdown, the aircraft departed the side of the road and struck a fence post. The engine was examined and test run, and no discrepancies were observed. The pilot stated that 'other pilots at the scene agreed the conditions could cause carburetor icing.' According to the FAA inspector present at the accident scene, 'the conditions were a classic setup for carburetor icing.' The Van's Aircraft construction and operating manual states that one method of building the carburetor heat system is to 'run a 2-inch air hose from a heat muff and position it to feed into the alternative air inlet of the carb[uretor] air box,' which is the method by which the pilot constructed the airplane. According to the inspector, the 2-inch hose is not large enough to adequately supply enough heat to the carburetor to sufficiently melt the ice. The aircraft was issued an airworthiness certificate by the FAA on August 24, 1995.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The development of carburetor ice resulting in a loss of engine power, and the inadequate carburetor heat shroud. Factors were the carburetor icing weather conditions, the kit manufacturer's inadequate carburetor heat shroud design, the FAA's inadequate certification of the aircraft, the snow covered, unsuitable terrain on which to perform a forced landing, and the fence post. Full narrative available
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