NTSB Identification: LAX07LA197.
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Accident occurred Friday, June 29, 2007 in Tucson, AZ
Probable Cause Approval Date: 03/31/2008
Aircraft: Evenson Roger J VANS RV-9A, registration: N394RS
Injuries: 1 Minor.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

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.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

the loss of engine power during takeoff-initial climb, which resulted from the owner/builder's improper adjustment of the supercharger waste gate valve, that resulted in the failure of the waste gate servo motor.

Full narrative available

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