On August 18, 2006, approximately 1905 Pacific daylight time, a Piper PA-24-250, N6249P, sustained substantial damage following the collapse of its main and nose landing gear during the landing roll at the Auburn Municipal Airport (S50), Auburn, Washington. The private pilot and his two passengers were not injured. Visual meteorological conditions prevailed for the personal flight, which was conducted in accordance with 14 CFR Part 91, and an instrument flight rules (IFR) flight plan was filed. The flight departed the Astoria Regional Airport (AST), Astoria, Oregon, about 1800, with its destination being S50. According to the Pilot/Operator Aircraft Accident/Incident Report (NTSB Form 6120.1), the pilot reported that after taking off from AST and following normal procedures to retract the landing gear, the gear did not retract. The pilot stated that he cycled the gear switch to the down position and that indications revealed the landing gear was down and locked. The pilot reported that he then elected to continue on his instrument flight rules (IFR) flight plan and proceed to S50, his destination airport. The pilot further reported that after he was cleared for the visual approach [to Runway 34] he closed his IFR flight plan and made a soft landing. The pilot stated that after the airplane touched down and rolled on its main wheels for about 50 to 75 feet, "...everything seemed normal." The pilot further stated that after the nose wheel touched the surface he could hear all three [landing] gear pop back up into the retracted position. The pilot reported, "...the prop started hitting the ground and then the fuselage settled and began sliding on the pavement. The only parts of the plane that touched the runway, other than the wheels, were the prop and the middle section of the belly." Two Federal Aviation Administration (FAA) aviation safety inspectors, who traveled to the accident site, reported that the firewall had sustained substantial damage. The inspectors also reported that there was damage to the fuselage skin on the underside of the airplane. A post-accident examination of the airplane revealed that the landing gear retraction motor had separated from its rear bulkhead attachment. An examination of the gear retraction motor attachment by an NTSB Materials Laboratory Senior Metallurgist, using an optical stereomicroscope, revealed that all rivets were fractured in the contact surface plane and had deformation and smeared features consistent with overstress fracture in shear. It could not be determined when the overstress event occurred.