What happened
During preflight operations, the pilot performed engine start and completed magneto and carburetor heat checks. After taxiing approximately 1,500 feet, the pilot waited at idle while several other aircraft landed and departed. The pilot configured the aircraft with takeoff flaps and takeoff trim prior to departure.
During the takeoff roll, the pilot noted that the airplane was not accelerating normally, though this was attributed to high summer temperatures. At approximately 1,000 feet down the runway, the aircraft briefly broke ground before settling back onto the surface. The aircraft became airborne again after another 100 feet of roll. As the pilot continued the takeoff, the sensation of abnormal acceleration persisted, leading the pilot to push the yoke forward and retract the flaps. The aircraft subsequently drifted off the left side of the runway, struck a parked airplane, and continued up an embankment before coming to rest partially on a road. The pilot reported that the engine was not running at the moment the aircraft impacted the parked plane.
The investigation
A post-accident examination of the aircraft revealed no mechanical discrepancies that could have contributed to the accident. Testing of the fuel showed it was clear, blue in color, and free of debris. However, a review of carburetor icing probability charts indicated that ambient conditions at the time of the event were consistent with moderate icing at cruise power or serious icing at glide power. A maintenance technician noted that the engine design is susceptible to carburetor icing on the ground due to the specific position of the air intake manifold. During a ground run-up performed after the accident, the carburetor box was found to be cold to the touch.
Findings
- The aircraft experienced abnormal acceleration during the takeoff roll.
- There were no injuries reported.
- Ambient conditions were conducive to moderate or serious carburetor icing.