The airplane nosed over during a forced landing following a partial loss of engine power in the takeoff initial climb. Just prior to the accident flight, the pilot adjusted the mixture control at the carburetor because previous test flights indicated that the mixture was running too rich. He contacted the carburetor manufacturer and was advised to adjust the setting no greater than one turn. The pilot adjusted the setting one complete turn. Following an operational ground test at 2,700 rpm (full power is 3,600 rpm), he departed and climbed the airplane to 300 feet. The engine did not develop full power and he attempted to correct the problem by leaning the mixture. The condition worsened so he landed the airplane in a field. The airplane was going through its Phase I flight test and the airframe and engine had accumulated approximately 6 hours. The pilot did not report any mechanical failures with the airplane or engine.

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

Index for Apr2005 | Index of months