NTSB Identification: LAX02FA188.
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Accident occurred Saturday, June 08, 2002 in Chandler, AZ
Probable Cause Approval Date: 09/13/2005
Aircraft: Fisher Celebrity, registration: N8205H
Injuries: 2 Fatal.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
During cruise flight, both of the left wings of the amateur built experimental biplane separated in flight. The airplane fuselage was a metal frame, and the empennage and wings were fabric covered wood. The pilot had contacted a friend, who was also constructing a Celebrity, a few weeks before the accident concerning loose fabric on the airplane's wings. The friend told the pilot not to fly the airplane until the loose fabric issue had been addressed. According to the friend, the pilot washed the airplane, let it dry in the sun, and noted that the loose fabric tightened up. The pilot believed that the loose fabric issue had been resolved. Various wing components were examined and compared with the building instructions and plan drawings. The examination revealed fracture features indicating that the wings failed in a positive overload event. No evidence of preexisting cracks or deteriorated wood was found. However, the comparison with the design revealed that the construction of the spars did not comply with their design drawings. In particular, the spars did not contain stiffener blocks adjacent to the upper and lower caps, and the filler blocks ended abruptly in a vertical line instead of tapering to the upper and lower caps. The filler blocks were thinner than specified in the plans and occupied 50 percent of the space between the spar caps instead of all the void. The filler blocks were also shorter than plan specification and did not taper according to the plan. Both of these conditions would reduce the load carrying capacity of the wing, especially in compression. The failure location was primarily at the outboard end of the filler blocks. No material defects were found during the examination.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: failure of the wing spars and the in-flight separation of the aircraft wing due to the builder's inadequate manufacture of this experimental aircraft. Also causal was the current owner/pilot's continued flight with known mechanical discrepancies.
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