LAX07LA197

During the takeoff initial climb, the pilot noted a high manifold pressure, and engaged the supercharger pressure override, but the manifold pressure remained the same. The engine began to lose power, and the airplane was no longer able to sustain a climb. The pilot attempted an emergency landing. During the landing sequence, the main gear hit brush and soft dirt, the nose gear dug in, and the airplane nosed over, coming to rest inverted. The airplane was powered by an Eggenfellner EJ-25, which was a water cooled, four cylinder, supercharged, Subaru automobile engine converted for aircraft use. Post accident examination of the engine revealed that a failed waste gate servo motor had prevented the waste gate valve from opening. Prior to the accident, the pilot adjusted the waste gate valve such that it was allowed to go over center and stick, causing failure of the servo motor.

History of flight

On June 29, 2007, at 0525 mountain standard time, an Evenson Roger J Vans RV-9A experimental airplane, N394RS, suffered a loss of engine power and collided with terrain during a forced landing near Tucson, Arizona. The pilot, who was the owner and builder, was operating the airplane under the provisions of 14 CFR Part 91. The private pilot, the sole occupant, sustained minor injuries; the airplane sustained substantial damage. The local area personal flight departed Ryan Field Airport, Tucson, at 0522. Visual meteorological conditions prevailed; no flight plan had been filed.

The pilot reported an uneventful pre-flight run-up; however, shortly after takeoff, the engine began to run rough. He noted a high manifold pressure warning light, and observed the manifold pressure to be 40 inches. He engaged the supercharger pressure override, but the manifold pressure remained the same. The engine began to lose power, and the airplane was no longer able to sustain a climb. Approximately 400 feet agl, the pilot began a gentle left turn, but believing he would not make the airport, elected to land 1 mile east in desert terrain. During the landing sequence, the main gear hit brush and soft dirt, the nose gear dug in, and the airplane nosed over, coming to rest inverted.

Airplane information

The airplane was powered by an Eggenfellner EJ-25, which was a water cooled, four cylinder, supercharged, Subaru automobile engine converted for aircraft use.

The pilot/builder examined the engine after the accident, and found the wastegate valve in the closed position. He stated that he was able to move the valve freely by hand. He tested the electrical wiring to the wastegate servo motor, and found no defects. He then tested the wastegate servo motor, and found that it would not respond to electrical input.

A representative of the engine manufacturer stated that prior to the accident, the pilot adjusted the wastegate valve such that it was allowed to go over center and stick. The over center condition had caused the 2-amp servo motor fuse to blow on two separate occasions. He further stated that the under these overload conditions, the servo motor most likely sustained damage that ultimately caused it to fail.