Incident Overview
A pilot reported an engine RPM loss while cruising at 1,800 feet above sea level en route to Everett. Attempts to correct the issue were unsuccessful, and application of carburetor heat further aggravated the RPM loss. Unable to maintain altitude, the pilot maneuvered the aircraft toward a field for a forced landing.
Landing and Damage
During the landing roll, the aircraft impacted a barbed wire fence and subsequently a ditch. The impact forces caused the nose gear assembly to separate from the airframe. No other damage items were specified beyond the nose gear separation.
Post-Crash Examination
A post-crash examination revealed no evidence of malfunction in the airframe, fuel system, or engine. Investigators estimated that at the aircraft's cruise altitude, the ambient air temperature was 19 degrees Celsius and the dew point temperature was 14 degrees Celsius. These conditions are consistent with moderate carburetor icing conditions.
Findings
The pilot's report indicated a degradation of engine RPM, which could not be corrected. The use of carburetor heat worsened the condition. The forced landing resulted in the aircraft striking a fence and ditch, leading to the separation of the nose gear assembly. No mechanical issues were found during the post-crash examination.