Oakdale Airport
Aircraft Accident/Incident Report

Oakdale, California 95361
Wednesday, February 8, 2006 15:15 PST

While entering the traffic pattern on the 45-degree entry, witnesses observed the amateur built airplane enter into a spin and impact the ground in a nose down attitude. One witness reported that the airplane was about 800 feet above the ground when he saw the wings "visibly vibrate." He saw the left wing collapse and fold rearward against the fuselage prior to the airplane entering into a spin. He further reported that he did not see anything depart the airplane. Other witnesses in the surrounding area, along with the first witness, reported that the engine sounded very loud, as if it were being revved up. They also reported that after the airplane had completed one full revolution to the right, the right wing collapsed and folded up against the fuselage. The Federal Aviation Administration (FAA) airworthiness inspector that responded to the site noted that the wings remained attached to the center section carry-through spar via their respective main spar bolts. The tail section remained attached to the empennage, with the rudder folded over the horizontal stabilizer. The entire airplane came to rest upright at the accident site. The cockpit area was thermally destroyed. The wing root areas sustained extensive thermal damage, as well as the entire tail section. The Safety Board IIC along with parties to the investigation inspected the airframe and engine at a later date following recovery of the wreckage. The airframe inspection revealed that the wings remained attached at their respective wing root attachment to center carry-through spar. Both wings' sustained severe thermal damage as a result of the post impact fire. The leading edge wing skins for both wings had separated from the wing spars and ribs about 6 feet from the wing tip inboard; the rivet holes were elongated and ovaled. Investigators noted that both wings and the associated main spars showed deformation about the longitudinal, lateral, and vertical axes of the wing with multiple "S" bends and twists in the main spars. The main wing aft attach points remained secured to the fuselage in the normal manner. The tail section remained attached to the fuselage, with damage consistent with impact forces. The engine inspection revealed no discrepancies that would have precluded normal operation. The degree of thermal destruction precluded a definitive determination of the sequence of failures within the wing structures.

the structural failure of the wings for undetermined reasons.