On June 11, 2015, at 1700 Pacific daylight time, an Eclipse Aviation Corp EA500 jet, N508JA, experienced a collapsed landing gear while taxiing to the active runway for departure at Sacramento Executive Airport (SAC), Sacramento, California. The airline transport pilot, a commercial pilot, and two passengers were not injured. The airplane was operated by Memly Aviation as a 14 Code of Federal Regulations Part 135 business flight. The airplane sustained substantial damage to the left wing. Visual meteorological conditions prevailed for the flight that was preparing to depart at the time of the accident, and an instrument flight rules (IFR) flight plan had been filed. The airplane was destined for San Francisco International Airport (SFO), San Francisco, California.
According to both pilots, the airplane was taxiing to the active runway when they heard a loud bang, and the airplane veered to the left. They contacted the tower asking if they had blown a tire. Tower personnel responded, and reported to the pilots that the airplane was leaking copious amounts of fuel onto the tarmac. The pilots shut down the airplane and evacuated the passengers. Upon further inspection of the airplane, the pilots reported that the left main landing gear trunnion had gone through the left wing.
According to the operator, the left main landing gear trunnion broke near the rear attachment point, which caused the landing gear to penetrate through the entire wing from bottom to top. The portion of the landing gear trunnion that failed, was housed behind a lower wing panel and would not have been visible to the flight crew.
The left main landing gear trunnion, part number M041-07H0101 serial number 0114, was original equipment and had accrued 1,275 hours and 1,492 cycles.
The left main landing gear assembly was shipped to the materials laboratory of the National Transportation Safety Board (NTSB). Visual examination revealed that the landing gear fractured at the trunnion portion of the landing gear. The smaller separated piece showed a fatigue crack that emanated from the inner wall. The crack itself was from a machining mark. The area outside of the fracture face contained rough features consistent with an overstress separation. The deep machining mark was in a portion of the trunnion where the inner wall tapered inward, and was in a transition region where the wall thickness was increasing in thickness. The assembly contained a metal squeeze-out typical of forging/casting parts. The excess metal squeezed-out of the forged/casting products are moved by machining, which renders them a high stress area.
According to the manufacturer, the initiation of the fatigue crack from a step machined inner wall of the trunnion was outside of the design requirements. Eclipse Aerospace, and the landing gear manufacturer, Mecaer Aviation Group, inspected for the presence of the machined steps. The manufacturer indicated that they had a systemic manufacturing defect that potentially effected the entire fleet of EA500 aircraft. Eclipse Aerospace and Mecaer, issued a mandatory Service Bulletin to address the issue. A fleet wide inspection/landing gear trunnion repair/replacement program identified as of May 9, 2016, that 126 airplanes had been inspected, with trunnion repaired or replaced when warranted. All owners of the EA500 airplane have been notified of the issue. The airplane and landing gear manufacturers further addressed inventory landing gear; the trunnions were reworked/repaired/replaced as warranted prior to shipment to Eclipse Aerospace. Mecaer also communicated with the machine shop responsible for the defect and process changes were put in place to prevent the issue for the existing inventory of landing gear.