NTSB Identification: LAX01FA253.
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Accident occurred Friday, July 20, 2001 in Palm Springs, CA
Probable Cause Approval Date: 07/31/2006
Aircraft: McDougall VERI EZE, registration: N25063
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.

The airplane collided with a wind turbine following an in-flight separation of the majority of the right canard and all of the right elevator. The accident occurred in an area that commonly had turbulent conditions. The airplane fragmented; the right canard and elevator were not in the main debris field, and were found about 1/2 mile from the main wreckage. The canard and elevator damage was not symmetrical. The left side remained intact and attached to the fuselage while the right side separated near the fuselage attachment points. All that remained of the right canard was the top skin, which had scattered patches of paint missing. The owner and the pilot built the airplane together. They acquired pieces for the airplane from different sources, and assembled the airplane. The owner did not recall who actually built the elevator. They obtained advice and technical suggestions from various builders of the model at their home field. They did not contact the kit manufacturer during construction. The kit manufacturer maintained close contact with builders through newsletters and a company website. They designed an improvement to the elevator, which incorporated a wider chord. They recommended that owners make the change if they had not flown their airplane. The manufacturer provided a full size diagram so that builders could physically place their piece on top of the drawing to insure that their manufactured piece conformed to the drawing. The accident elevator did not conform to the kit manufacturer's instructions. In a newsletter to builders, the manufacturer informed them that the airplanes would be difficult or even dangerous to fly if the elevators did not have the correct cross section. The kit manufacturer repeatedly stressed the importance of the correct shape, weight, and balance of the elevators in their newsletters. On two occasions, once in 1979 and again in 1988, they noted that builders had installed balance weights in improper locations. In one case the builder experienced flutter, and investigation determined that he added weight to balance a reconstructed elevator. Instead of dividing the added weight between inboard and outboard mass balance points, he placed them all on the inboard point. The manufacturer noted that this was incorrect, and that the balance weights should not all be installed inboard. They stated that any variance of weight, stiffness, or shape from recommended design specifications should be considered dangerous, and builders should discard elevators that did not conform. The accident airplane had a large number of balance weights, and all of them were at the inboard mass balance point.

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

the failure of the builder to balance the elevators per the kit manufacturer's instructions resulting in flutter and in-flight separation of the right elevator.

Full narrative available

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