ERA11LA264

The student pilot entered the left downwind leg of the traffic pattern at the airport. While on the final leg of the traffic pattern, the airplane encountered vertical wind shear and landed hard on the runway. After the impact, the right main landing gear of the airplane collapsed, and the pilot taxied off the right side of the runway, coming to rest perpendicular to the runway. The most recent annual inspection was performed 3 months before the accident, and at that time the airplane had accumulated 13,962.8 hours of total time in service. The airplane was involved in another accident 2 months earlier that involved a hard landing. Thirteen days before the accident, the most recent maintenance was completed on the airplane that involved an inspection of the main landing gear. The airplane was found to be in airworthy condition, was signed off on that date, and at that time had 14,055.3 hours of total time in service. Examination of the inboard torque link lug of the right main landing gear revealed that it failed as a result of progressive fatigue cracking. The lugs are the subject of a Piper service bulletin recommending repetitive 100-hour recurrent inspections for cracking in the lugs. Although the complete loading history of the gear is unknown, it is likely that detectable indications of metal fatigue would have been present for more than 100 flight hours. There was no documentation in the airplane’s maintenance records that indicated that the factory service bulletin had been performed.

On April 22, 2011, about 1625 eastern daylight time (EDT), a Piper PA-28-161, N2838D, had the right main landing gear collapse during landing at Meriden Markham Municipal Airport (MMK), Meriden, Connecticut. The student pilot was uninjured. The airplane sustained substantial damage to the right wing. Visual meteorological conditions prevailed, and no flight plan was filed for the solo personal flight, which was conducted under the provisions of 14 Code of Federal Regulations Part 91. The flight originated from Waterbury-Oxford Airport, Oxford, Connecticut, around 1430. According to the student pilot, he arrived at the airport around 1325, completed the preflight inspection, and found no anomalies with the airplane. He started the engine and completed an engine run-up, then departed the airport without incident. He landed at Danielson Airport (LDZ), Danielson, Connecticut, then taxied back to the runway and departed LDZ for MMK around 1610. At that time, the pilot reported everything was "normal." The student pilot entered the left downwind leg of the traffic pattern at MMK for runway 18. When he turned onto the final leg, he input full flaps and lowered the airspeed to 73 knots. The airplane encountered "vertical wind shear" and landed "hard" on the runway. After the impact, the right main landing gear of the airplane collapsed and the pilot taxied off the right side of the runway, coming to rest perpendicular to the runway. The airplane was examined at the accident scene by a Federal Aviation Administration (FAA) inspector. According to the inspector, the right wing was wrinkled at the wing root aft of the main spar and dented on the forward outboard section of the wing. Examination of the landing gear revealed that the right main landing gear cylinder torque link attachment point was fractured from the right main landing gear assembly. A visual examination of the fracture surface indicated that it was partially discolored. According to the pilot, he held a student pilot certificate issued in May of 2009. His most recent second class medical certificate was issued on May 20, 2009. He reported 139 total hours of flight time, of which, 67 hours were in the same make and model as the accident airplane. According to FAA records, the airplane was manufactured in 1979, and was registered to an individual in 2008. It was a single-engine, fixed tricycle gear, monoplane that was equipped with a Lycoming O-320 series, 180-horsepower engine. The most recent annual inspection was performed on January 13, 2011. At that time, the airplane had 13,962.8 hours of total time in service. The airframe maintenance records indicate that on May 4, 2010, a mechanic "rebuilt the left and right main struts." At that time, the airplane accumulated 13,457.7 total hours in service. According to National Transportation Safety Board records, the accident airplane was involved in an accident (ERA11CA187) on March 12, 2011. The accident occurred on an instructional flight andinvolved a hard landing. According to the airframe maintenance records, the most recent maintenance performed on the airplane occurred on April 9, 2011, which was after the first airplane accident. The engine was removed from the airplane, inspected, and reinstalled. In addition, both the left and right main landing gear struts were inspected for condition and serviced with nitrogen. The airplane was signed off, and at that time, it had 14,055.3 total hours of time in service. An examination of the right main landing gear strut cylinder by the Safety Board Materials Laboratory revealed that the outboard lug fracture was consistent with an overstress separation and there were no indications of a preexisting crack. In contrast, the inboard lug fracture was darkly discolored across the majority of the fracture with a prominent arrest line consistent with a preexisting crack. Fracture markings indicated that the fatigue initiated on the machined outboard surface of the lug at several locations in a small region near the lower edge of the fracture. Cast main landing gear struts on certain Piper PA-28's are the subject of Piper Service Bulletin 1131, dated August 18, 2003. Although it was not mandatory, the service bulletin applied to the accident airplane. The service bulletin recommended a repetitive 100 hour inspection for cracks in the torque link lugs on all cast landing gear strut cylinders. The service bulletin also indicates that a forged strut cylinder was available and if installed, the airplane would be exempt from the periodic inspections. A metallographic cross section through a portion of the fractured cylinder performed by the Safety Board Materials Laboratory confirmed that the accident strut cylinder was cast aluminum. The airframe maintenance records did not include a list of applicable service bulletins. In addition, a review of the maintenance records did not indicate that Piper Service Bulletin 1131, dated August 18, 2003, was performed.