NTSB Identification: SEA08CA184.
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Accident occurred Monday, August 18, 2008 in Moses Lake, WA
Probable Cause Approval Date: 09/26/2008
Aircraft: Wheat Excalibur EX, registration: N2505Q
Injuries: 2 Uninjured.

NTSB investigators used data provided by various entities, including, but not limited to, the Federal Aviation Administration and/or the operator and did not travel in support of this investigation to prepare this aircraft accident report.

The pilot was on a local, personal flight in an experimental airplane. While in cruise flight approximately 600 feet above ground level he heard a loud bang and the airplane entered a right turn. The pilot used aileron to counteract the turn; however, the airplane descended into the reservoir below. Post accident inspection showed that the rivets securing the rudder pedals had sheared in overload and there was no evidence of corrosion. During the impact sequence, the fuselage sustained structural damage. According to the kit supplier, the rudder pedal horns are secured using three rivets per pedal. The kit supplier indicated that the rivets could be put under excessive stress while operating the airplane over gross weight and/or powering the airplane with an engine that produces over 65 horsepower. The engine installed in the airframe produced 85 horsepower. As a result of the accident, the kit supplier suggested that the builders include a rudder pedal security check and if they are loose, replace two of the three rivets with two bolts. All future designs kits produced and shipped will include the bolts.

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

The right rudder pedal attach rivets sheared due to overload.

Full narrative available

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