NTSB Factual Report

On June 25, 1993, at approximately 0930 mountain daylight time, an Osprey GP-4, N85Z, experimental homebuilt aircraft, had an airframe in flight failure while in cruise flight approximately 15 miles northeast of Canon City, Colorado. The commercial certificated pilot, who was the builder, received fatal injuries and the aircraft was destroyed. Visual meteorological conditions prevailed for this local personal flight which departed Canon City at 0915. No flight plan was filed.

Examination of the accident site provided information on wreckage distribution and a wreckage distribution diagram is attached. The scatter pattern was oriented on a base course of 270 degrees and the canopy was the first item in the wreckage distribution pattern. Approximately 400 yards beyond the canopy, the tail section was found and 200 yards further along the elevator control rods and the pilot's headset were found. The main wreckage was located approximately 1400 yards from the canopy.

Detailed examination of the canopy provided information that the canopy latch was separated from the canopy and the retention screws had pulled out of the mounting structure. The cross brace located in the rear of the canopy was fractured and indentation marks on the canopy edge were present.

The vertical and horizontal stabilizer were separated from each other and the left horizontal stabilizer had indentations which matched the damage found on the canopy edge. The stabilizers pulled free from the empennage in a rearward direction and the wood structure provided evidence of longitudinal overload.

The fuselage, wings, and engine impacted into cedar trees which varied in height from 8 to 12 feet. The wooden structure disintegrated upon impacted into several sections, and the engine remained attached to the mounts.

The propeller remained attached to the engine. One blade was bent rearward eight inches inboard from the tip. The other blade contained an 'S' curve along its span and incurred leading edge gouging and chordwise scratches.

Detailed aircraft specifications were obtained from the designer and discussions were held with him as regards various canopy design and structural elements. Review of this material provided information that the canopy latch was of the trunk type and did not match the required design specifications. In addition, it was found that the canopy hold down faring was constructed from a light fiberglass material vice the .050 aluminum material in the design specifications. Review of available information provided information that these specifications are required due to the canopy lift co-efficient at 200 mph which is approximately 50 psi. Details of GP-4 design and construction are attached.

NTSB Probable Cause

FAILURE BY THE PILOT/BUILDER TO FOLLOW CONSTRUCTION SPECIFICATIONS AND THE USE OF IMPROPER MATERIALS DURING CONSTRUCTION OF THE AIRCRAFT.