What happened
On March 21, 2016, a privately owned Cirrus SR22T, registration JA01YK, was conducting a familiarization flight from Nagasaki Airport to Kagoshima Airport. The flight included the captain and four passengers. Upon landing on runway 34 at Kagoshima Airport, the aircraft's nose landing gear strut assembly fractured. This structural failure caused the nose of the aircraft to drop and make contact with the runway, preventing the aircraft from taxiing further. The aircraft came to a stop on the runway, sustaining minor damage to the engine cowling and propeller blades, but no injuries were reported among the five occupants.
The investigation
The Japan Transport Safety Board (JTSB) conducted an investigation involving airframe examinations and on-site inspections. Detailed fracture surface analysis of the nose landing gear strut assembly was performed at the National Transportation Safety Board (N/A) laboratory. The investigators examined the aircraft's maintenance history, flight data from the Aircraft Data Logger (ADL), and air traffic control records. The investigation also looked into the pilot's landing techniques and the presence of mechanical vibrations, specifically shimmy, during previous operations.
Findings
Investigation findings revealed that an undetected fatigue crack had developed at the forward edge of the gusset tube weld bead on the strut tube prior to the incident. This crack significantly reduced the structural integrity of the nose landing gear. The progression of this crack was likely driven by two main factors. First, the repeated occurrence of shimmy—a type of oscillating vibration—during landings contributed to the crack's initiation. Second, the pilot demonstrated a consistent operational tendency to initiate left turns to vacate the runway before the aircraft had sufficiently decelerated. This maneuver applied high tensile stress to the left side of the strut tube. Ultimately, the weakened strut could no longer withstand the loads applied during the landing on March 21, leading to the fracture of the nose landing gear strut tube.