What happened
On May 31, 2014, at approximately 10:10 UTC, an Extra 300/200 was performing an aerobatic training flight, having departed from Innsbruck Airport earlier that morning. During the flight, the pilot notified the Innsbruck Tower of control issues involving the rudder, expressing concern that the aircraft might be unable to maintain the centerline during landing due to a suspected failure in the right rudder control linkage.
Upon landing on runway 08, the pilot was unable to keep the aircraft on the runway. The aircraft veered left, exiting the runway pavement and coming to a stop in the northern safety area. The impact caused the right landing gear strut to break. The pilot sustained no injuries.
The investigation
The Austrian Federal Safety Investigation Board (SUB) examined the wreckage and the control systems of the aircraft. Investigators focused on the condition of the rudder control cables and the pulleys. Microscopic and scanning electron microscopy (SEM) analysis was performed on the broken cable ends to determine the nature of the failure. The investigation also reviewed the manufacturer's service manuals regarding inspection procedures for flight control systems.
Findings
- The right rudder control cable had snapped in the area of the rear pulley within the fuselage.
- Examination of the cable revealed significant wear, with the outer strands of the wires being heavily abraded on one side due to contact with a cable guide eye.
- The failure was characterized by a mechanical abrasion of the cable strands, which eventually led to a complete break of the cable.
- The right landing gear strut was broken, and there was damage to the underside of the right wing and the wingtip device.