Accident Summary
On October 7, 2021, at approximately 0654 mountain daylight time, a Piper PA-24, registration N5585P, sustained substantial damage during an accident near Northern Colorado Regional Airport (FNL) in Fort Collins, Colorado. The flight was operated as a personal flight under Title 14 Code of Federal Regulations Part 91. The pilot reported minor injuries and the passenger was not injured.
Flight Sequence
During takeoff from Runway 15, the pilot reported that the airplane was unable to climb normally and that an engine overspeed occurred, reaching about 2,900 rpm. The pilot reduced throttle, observed a loss of airspeed, and heard a loud bang from near the engine. A forced landing was executed on a road, during which the airplane struck a pole, substantially damaging the left wing.
Automatic dependent surveillance-broadcast (ADS-B) data showed that the airplane began taxiing at about 0645 and the takeoff roll commenced around 0652. The aircraft accelerated to 62 knots groundspeed about 1,800 feet past the runway threshold and lifted off at 71 knots groundspeed approximately 3,200 feet past the threshold, which was 5,300 feet from the departure end of the 8,500-foot runway.
During the initial climb, about 3,500 feet from the departure end, the airplane decelerated to 60 knots groundspeed and continued flying at 50-60 knots groundspeed at low altitude. Approximately 2,800 feet beyond the departure end, the airplane touched down on a paved road at 59 knots groundspeed. Initial propeller strike marks on the road were spaced 1.17 feet apart, corresponding to an engine speed of about 2,554 rpm at touchdown.
Examination and Performance
Postaccident examination found no evidence of mechanical anomalies or malfunctions. The propeller governor was bench tested and met manufacturer specifications.
The pilot reported that the airplane's takeoff weight was approximately 300 pounds below the maximum gross weight. Manufacturer performance data indicated a takeoff ground roll of about 1,900 feet at maximum gross weight with no wind.
Pilot Actions and Atmospheric Conditions
During the engine runup before takeoff, the pilot reported pulling the carburetor heat lever out "for a few seconds" and that the engine ran "a little rough" during that period. A review of the icing probability chart from FAA Special Airworthiness Information Bulletin CE-09-35 indicated that the atmospheric conditions at the time of the accident were "conducive to serious icing at cruise power."
The pilot recalled setting the mixture lever "about a finger" width toward the lean position for takeoff.
After the accident, the pilot stated that he should have aborted the takeoff due to the airplane's slower-than-normal acceleration.