19970320003339A

Aircraft wings came apart while aircraft making a pass over airport. (.4) the pilot (plt) departed cookson, OK, in a homebuilt aircraft (acft) for an approximate 30 minute flight to stilwell, OK. Witnesses at stilwell said he made a low pass on a northerly heading (about 50 ft off the ground) at a high rate of speed. One witness estimated the acft was traveling faster than 200 mph, when he saw the acft's right wing skin separate from the acft. The right wing then came off. The acft was observed to roll several times & travel about 1100 ft before it impacted the ground. Postimpact examination of the wreckage revealed a fracture in the wing spar about 18 inches in from the right wing tip. There was a discoloration in the fracture, which had the appearance of a varnish like substance. An FAA inspector reported that 'there were different color glue joints in the wing construction indicating that there were different kinds of glue used.' Also, the failure mode differed; the dark glue joints failed in the wooden structure, where as, the other glue joints failed in the bond. Some of the wing joints that had failed had discoloration between the rib & the wooden skin. The inspector suggested that 'either improper clamping during construction, prevarnishing of the contact surfaces, or bond separation followed by moisture weathering could have caused this.' The plt had purchased the homebuilt acft on 10/1/96. It had been originally certificated for flight on 10/27/72. On 2/11/73, it had been damaged during a takeoff mishap, & 'new wing construction' had been performed. (-23) aircraft was flying north bound parallel to the runway at the cherokee nation airport in stilwell, OR, when the r/h wing began to break apart, then separate from the aircraft causing loss of control. Aircraft impacted the ground approximately 290 feet east of the runway. Debris from the r/h wing was discovered approximately 850 feet south of the impact point.