N525BB

On May 3, 1997, about 1900 Alaska daylight time, a wheel equipped homebuilt, experimental Hammer, Avid Flyer airplane, N525BB, crashed during the initial takeoff climb from the Chitina Airport, Chitina, Alaska. The airplane was being operated as a visual flight rules (VFR) cross-country personal flight to McCarthy, Alaska, when the accident occurred. The airplane, operated by the pilot, sustained substantial damage. The certificated private pilot, the sole occupant, was not injured. Visual meteorological conditions prevailed.

On May 4, 1997, at 1222, the pilot reported in a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), that he just departed runway 13 at Chitina and climbed to about 250 feet above the ground. The engine, a Rotax 618, suddenly quit. The pilot made a 180 degree turn to return to the runway. The pilot performed an emergency landing short of the runway into low brush. The airplane received damage to the fuselage and wingtips.

On November 20, 1997, the pilot reported the engine was last overhauled 5 hours before the accident at a facility in Birchwood, Alaska. During the overhaul, one of the engine's two pistons was replaced with an oversize piston. The piston cylinder was also bored oversize. The second engine piston was not replaced, and remained standard size.

After the accident, the pilot sent the engine to an overhaul facility in San Leandro, California. The examination revealed the oversize engine piston was found seized in the cylinder. Measurement of the oversize piston revealed it was the same size as the cylinder bore, both measuring 2.998 inches.