Primary finding
Probable cause
A loose stand-off clamp which resulted in a throttle assembly malfunction, and the inability of the engine to produce full power during the attempted takeoff.
Investigator assessment
Analysis narrative
On the day of the accident, the pilot decided to take his airplane on a flight around the traffic pattern at his home airport to practice a few takeoffs and landings. After pulling the airplane out of the hangar where he kept it, he performed a preflight inspection. He then performed an engine runup, then back taxied on the runway for takeoff. Once he was in position for takeoff, he advanced the throttle until it was full open, and at 65 mph and about 2/3rds of the way down the runway, he rotated. He immediately realized that the engine was not producing full power, and attempted to advance the throttle further, but he realized that the throttle seemed as though it was not advancing completely. He then nosed the airplane down to attempt to stay in ground effect and gain some airspeed. A lake was at the departure end of the runway, and he was already approaching the trees on the opposite bank. He then picked a spot between trees, turned the fuel off, and pulled the aircraft into a full stall prior to impact. Postaccident examination of the airplane revealed that the fuselage and wings were substantially damaged. Further examination also revealed that the throttle cable would resist efforts to fully open the throttle and would only move the throttle arm on the carburetor about 1/2 an inch, and when the throttle was fully open, the entire throttle cable would move through the firewall and bulge. After disconnecting the cable from the carburetor, the cable was found to be still under load, until a loose stand-off clamp that connected the throttle cable to the firewall was repositioned, which then allowed the throttle to function properly through its full range of motion.