WPR11LA370

During the landing roll on the grass airstrip, the nose of the airplane began to drop, and the pilot confirmed that he was not applying excessive brake pressure. The nose continued to descend, then the airplane dropped back onto the tailwheel and onto its left wing. Examination revealed that the left main landing gear aft strut failed, and signatures consistent with a preexisting crack in the aft landing gear strut at the axle knuckle were observed. The area of failure was obscured by fabric covering material, thereby limiting the pilot’s ability to observe the crack during a preflight check.

HISTORY OF FLIGHT On July 23, 2011, about 2040 mountain daylight time, a Piper J5A, N38AW, experienced a left main landing gear collapse during the landing roll near Biddle, Montana. The pilot was operating the airplane under the provisions of Title 14 Code of Federal Regulations Part 91. The private pilot and passenger were not injured. The airplane sustained substantial damage to the left side of the fuselage during the accident sequence. The local flight departed from a private airstrip near Biddle about 2000. Visual meteorological conditions prevailed, and no flight plan had been filed. The pilot reported a normal takeoff and flight, with a subsequent uneventful landing on the grass airstrip. During the landing roll, the nose of the airplane began to drop, and the pilot confirmed that he was not applying excessive brake pressure. The nose continued to descend, and the airplane then dropped back onto the tailwheel, and then onto its left wing. Subsequent examination revealed that both of the upper landing gear struts had separated at the axle knuckle. Black dust and residue was present around the fracture surface of the aft strut. Examination of the corresponding right landing gear struts revealed that the area of failure was obscured by fabric covering material.