Incident Overview
On March 21, 2016, at approximately 13:20 Japan Standard Time, a privately owned Cirrus SR22T, registration JA01YK, experienced a fracture of the nose landing gear strut tube upon landing on Runway 34 at Kagoshima Airport. The aircraft came to a stop leaning forward with its nose in contact with the runway. The five occupants—a captain and four passengers—were not injured. The aircraft sustained minor damage and no fire occurred.
Flight History
The flight originated from Nagasaki Airport at 12:46 as a visual flight rules familiarization flight. The captain, seated in the left seat, flew with four passengers toward Kagoshima Airport. Air traffic control communications and radar data indicate that the aircraft coordinated with the Kagoshima Tower, extended its downwind leg to follow a preceding arrival aircraft, and received landing clearance. The captain reported that the approach was normal, with the wind showing a tailwind component of 6 knots and a crosswind component of 3 knots, which were not considered significant. After touchdown on the main landing gear, the captain intended to vacate the runway via taxiway T3 without applying brakes, due to the need to avoid hard braking.
Aircraft Damage and Examination
Examination of the nose landing gear revealed that the strut tube had fractured at the forward toe of the gusset tube weld bead. Fracture surface analysis, conducted at the National Transportation Safety Board laboratory in the United States, identified a fatigue crack that had initiated and progressed prior to the incident. The crack reduced the strength of the strut tube, leading to fracture under the landing load.
Probable Causes
The Japan Transport Safety Board determined that the serious incident occurred because the aircraft could not taxi after the nose landing gear strut tube fractured at landing, causing the aircraft to stop with its nose on the runway. The fracture was probable due to an undetected fatigue crack at the forward toe of the gusset tube weld bead that progressed and significantly reduced the strut tube's strength. The initiation and progression of the fatigue crack were somewhat likely contributed to by repeated occurrences of shimmy during landings. Additionally, the captain's tendency to initiate a left turn at a speed with insufficient deceleration when vacating the runway likely contributed to repeated high tensile stress on the left side of the weld bead, further propagating the crack.