What happened
On April 30, 2001, an Austrian-registered Cessna 560 Citation V, registration OE-GSW, was performing an air taxi flight from Innsbruck to Florence. After a normal approach to runway 05, the aircraft was unable to decelerate sufficiently on the runway. The aircraft overran the end of the runway at threshold 23, following a slightly curved path to the right. After traversing two bumps, the aircraft came to a halt after striking the airport perimeter fence. There were four occupants on board, including the crew and two passengers; all survived the event with only minor injuries.
The investigation
The ANSV examination of the wreckage revealed significant damage to the aircraft. The nose gear had separated from the airframe, and the right main landing gear assembly—including the piston, brake caliper, and wheel—was also detached. Investigators found that the right landing light support structure had been damaged by interference with the tire. Furthermore, the flexible brake lines for both the normal and emergency braking systems had been torn from the right brake caliper.
Technical analysis of the right main gear piston identified a pre-existing circumferential crack affecting approximately 80% of the load-bearing section. Although the component was designed for a fatigue life of 10,000 landings, it had only completed 4,956. The investigation also noted that the aircraft was not equipped with a Cockpit Voice Recorder (CVR) or Flight Data Recorder (FDR).
Findings
- The primary cause of the accident was a loss of hydraulic pressure caused by the failure of the right main gear strut's seal.
- The pre-existing crack in the right main gear piston caused the strut to extend to its maximum limit, which subsequently tore the flexible brake lines from the brake caliper.
- The design of the braking system was vulnerable to a single failure; the loss of the strut's seal led to the simultaneous loss of both the normal and emergency braking systems.
- The crew could not rule out the possibility that they had failed to release the normal brake pedals before applying the emergency brake, a procedural error that would have prevented the emergency system from functioning effectively.