Amateur-built Pitts S-1 N347MM accident near St. Petersburg, Florida

Probable cause

The pilot's failure to maintain adequate airspeed following a partial loss of engine power, which resulted in an aerodynamic stall. Contributing to the accident was improper maintenance practices during the construction of the airplane, which resulted in contaminants being accidently introduced into the fuel system.

NTSB analysis

The pilot/owner, who was also the builder of the airplane, was attempting to conduct its first flight. He taxied to the runway and encountered some engine roughness during the magneto check, but the roughness was successfully eliminated after he conducted a "lean burn-out" and a second magneto check. The pilot contacted the air traffic control tower for permission to remain in the traffic pattern and was cleared for takeoff. He taxied into position on the runway, applied full power, and was satisfied with what he "saw, heard, and felt." Since this was the initial flight of the airplane, the pilot planned to hold the airplane in ground effect after liftoff, in order to accelerate to an airspeed above the prescribed normal climbout speed. The airplane had climbed to approximately 20 feet above ground level when a partial power loss occurred. The pilot decided to abort the takeoff, but the airplane stalled and rolled "very hard" to the right. It descended, struck the runway inverted, and slid inverted to a stop. The pilot sustained minor injuries. Subsequent to the accident, the engine fuel distribution system failed a flow bench test. Examination of the system's components revealed that the fuel servo was contaminated with fragments of material similar to the fuel line material and that the screens on some of the fuel injector nozzles were partially occluded by paint. The servo contamination was a result of the pilot's self-developed shortcut for fabricating the fuel lines, and the paint was inadvertently deposited on the injector screens when the pilot painted the engine.

Text from the NTSB. Open the NTSB docket for NYC08LA213 for the full record.