Not trying to start controversy and I suppose the real story will never be known:
I eves dropped on a conversation Jimmy Leeward was having with someone and there was a "think group" that seems to believe the plane experienced flutter, which caused the fabric to be torn off on a large scale as the structure failed. The NTSB is convinced the fabric tore off first due to faulty application, which caused flutter. Leeward indicated that he and others personally examined the wreckage and their explanation is valid. Flutter and fabric detachment is agreed by both sides, there is disagreement on which came first.
The NTSB reached their conclusion because the complete line of stits/polyfiber products was not used from start to finish. They determined this by locating an ink stamp on the fabric (that is they examined all the fabric in the wreckage until they found a brand marking. Had the ink stamp not been found, the fabric would have been classified as "uncertified polyester" which would have weakened a "didn't follow the manual" argument. (Other sources say only some of the fabric was Stits branded; the rest was generic polyester Steve had lying around). Ray Stits indicated it would have been better had the ink stamped fabric not been found, however, in his testimony to the NTSB he stated the process used would not offer the best adhesion to a plywood surface (partly because that is how the question was asked). Based on the information Steve had when he built the plane, I would not fault him for his choices in covering; polyester fabric and butyrate dope on plywood was an accepted practice then, provided the dope was properly thinned to penetrate the wood. Steve knew what he was doing.
Rewind ~2yrs before the accident, I was looking at the O&O at OSH. The fabric finish on the top of the wings was poorly executed. May have been partly due to age of the covering at that point. The dope was mottled and the fabric had lifted off the wing's plywood covering in several places where one could "drum" on the fabric. Not sure if that was due to products used, bad/expired/wrong type or just poor workmanship. Walking Wittman historian, Jim S. (and that is intended respectfully) indicated Steve was aware of the wing fabric and planned to recover the wings in the near future. However, the plane flew for a long time in that condition (>2yrs) which undermines the NTSB theory that this was a sudden/catastrophic failure event.
There are a couple of attempts to re-create the O&O airplane. The party in GA that purchased the O&O wreckage and drew plans for the airplane has an example under construction. There was another mostly complete airplane (may have flown) but the status is unknown. At some point in the future, there should be O&O replicas flying. While I would hate to see one discover a flutter mode by accident, there would be a certain satisfaction in knowing it exists because the NTSB is not the all knowing wizard as some believe.
