NTSB Factual Report

On June 7, 2004, at 1302 mountain daylight time, an amateur-built Betchan KR II, N250KB, was destroyed during a forced landing following a loss of engine power shortly after takeoff from runway 32 (8,701 feet by 150 feet, concrete) at the Rapid City Regional Airport (RAP), Rapid City, South Dakota. The personal flight was operating under 14 CFR Part 91 and was not on a flight plan. Visual meteorological conditions prevailed. The pilot sustained minor injuries. The flight was departing RAP at the time of the accident.

In his written statement, the pilot reported that the takeoff was routine through 300-400 feet above ground level (agl) when the engine lost and then regained power. He notified the RAP control tower and was attempting to return to the airport when the engine lost power again. He reportedly turned to the left in order to avoid some hills in front of the aircraft. He maneuvered the aircraft again to avoid power lines "only to stall-slide into the terrain." The aircraft impacted the side of a small hill less than one-quarter mile west of the airport.

A post-accident examination revealed that the left valve cover and rocker arms had separated from the engine. The valve cover and three of the four rocker arms were present in the vicinity of the engine. The fourth rocker arm was not located. In addition, the left side valve push rods had also separated from the engine and were located in the debris. The valve cover was dented in a manner consistent with impacts to the internal side of the cover. The cylinder heads and valves appeared intact. Continuity of the remaining engine components was verified through crankshaft rotation. The carburetor and gascolator separated during impact. The wooden propeller was shattered, however, the hub remained attached to the propeller flange. Flight control continuity was verified.

NTSB Probable Cause

Failure of the engine rocker arm installation resulting in a loss of engine power. A contributing factor was the power lines.