Accident Details
On April 22, 2011, at approximately 1625 eastern daylight time, a Piper PA-28-161, registration N2838D, experienced a collapse of the right main landing gear during landing at Meriden Markham Municipal Airport (MMK) in Meriden, Connecticut. The student pilot, who was the sole occupant, was uninjured. The aircraft 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 14 Code of Federal Regulations Part 91. The flight originated from Waterbury-Oxford Airport in 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, completed an engine run-up, and departed without incident. He landed at Danielson Airport (LDZ) in 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 collapsed, and the pilot taxied off the right side of the runway, coming to rest perpendicular to the runway.
Aircraft Information
The airplane was a Piper PA-28-161, manufactured in 1979, and was registered to an individual in 2008. It was a single-engine, fixed tricycle gear monoplane equipped with a Lycoming O-320 series, 180-horsepower engine. The most recent annual inspection was performed on January 13, 2011, at which time the airplane had 13,962.8 total hours in service.
Pilot Information
The pilot held a student pilot certificate issued in May 2009 and a second class medical certificate 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.
Maintenance History
The airframe maintenance records indicated that on May 4, 2010, a mechanic "rebuilt the left and right main struts" at 13,457.7 total hours. The airplane was involved in a prior accident (ERA11CA187) on March 12, 2011, during an instructional flight, which involved a hard landing. The most recent maintenance occurred on April 9, 2011, after the first accident. The engine was removed, inspected, and reinstalled. Additionally, both the left and right main landing gear struts were inspected for condition and serviced with nitrogen. The airplane was signed off with 14,055.3 total hours.
Examination Findings
An examination by a Federal Aviation Administration (FAA) inspector revealed that the right wing was wrinkled at the wing root aft of the main spar and dented on the forward outboard section. The right main landing gear cylinder torque link attachment point was fractured from the assembly, with a partially discolored fracture surface.
Further examination by the National Transportation Safety Board (NTSB) Materials Laboratory determined that the outboard lug fracture was consistent with an overstress separation and showed no indications of a preexisting crack. In contrast, the inboard lug fracture was darkly discolored across most of the fracture, with a prominent arrest line consistent with a preexisting crack. Fracture markings indicated fatigue initiated on the machined outboard surface at several locations near the lower edge.
Piper Service Bulletin 1131, dated August 18, 2003, applied to the accident airplane. Although not mandatory, it recommended a repetitive 100-hour inspection for cracks in the torque link lugs on all cast landing gear strut cylinders. The service bulletin also noted that a forged strut cylinder was available; if installed, the airplane would be exempt from the periodic inspections. A metallographic cross section confirmed that the accident strut cylinder was cast aluminum. The airframe maintenance records did not include a list of applicable service bulletins, nor did they indicate that Piper Service Bulletin 1131 had been performed.