Incident Overview
On April 22, 2019, at approximately 2020 mountain daylight time, a Piper PA-18 (registration N727WW) sustained substantial damage after impacting trees near McCall, Idaho. The private pilot, the sole occupant, was not injured. The aircraft was operating under Title 14 Code of Federal Regulations Part 91 as a personal flight.
Pilot Report
The pilot reported departing around 1900 with 14.5 gallons of fuel on board. While approximately 10 miles east of the intended destination, he initiated a cruise descent for landing at a reduced power setting. Shortly after reducing power, the engine continued running but ceased to respond to throttle inputs. The pilot attempted to troubleshoot the issue but was unable to restore throttle response. As the airplane continued descending, the pilot slowed it as much as possible before impacting trees. The airplane came to rest suspended in a tree about 4 miles from the destination airport.
Post-Accident Examination
During recovery, approximately 1.5 gallons of fuel were drained from the right wing fuel tank, while no fuel was recovered from the left tank. Both fuel tank caps were found securely installed, and the fuel selector was set to the left tank position. The gascolator bowl contained no fuel. The carburetor was disassembled and found free of anomalies or contaminants; about one tablespoon of clear blue liquid consistent with 100 low-lead aviation fuel was drained from the carburetor bowl. The oil filter was cut open and contained no metallic debris. The spark plugs and magnetos showed no anomalies, and borescope examination of the cylinders revealed normal operating signatures.
Atmospheric Conditions
The atmospheric conditions at the time of the accident were conducive to the development of carburetor icing at glide power settings.
Probable Cause
No probable cause was determined by the investigation.