What happened
On the morning of November 3, 2010, a Robin R1180 T Aiglon, registration F-GZIF, was performing a landing on runway 14 at La Réunion aerodrome. During the landing roll, the pilot discovered that the rudder was unresponsive to pedal inputs. As soon as the nose wheel made contact with the paved surface, the pilot found it impossible to steer the aircraft. To prevent a runway excursion, the pilot applied the brakes to bring the aircraft to a halt on the runway. The aircraft was subsequently towed to a hangar.
The investigation
Investigators examined the aircraft's control system and identified a breakage in the left control cable, which connects the right rudder pedal to the rudder surface. The failure occurred near a return pulley located on the floor beneath the dashboard. Both ends of the broken cable exhibited fraying.
Upon inspecting the pulley, investigators noted significant wear and friction marks on the right side of the pulley and its U-shaped support. Interestingly, the U-shaped support did not match the part description in the aircraft's parts catalog, which illustrated an L-shaped two-piece support; however, the aircraft's floor lacked the necessary mounting holes for such a part, suggesting the U-shaped component was likely an original part.
Further inspection revealed that the cable had jumped out of the pulley groove. The retaining pin, intended to prevent the cable from exiting the guide, was missing. The mounting holes for this pin were clogged with dust, indicating the pin had been absent for some time. Additionally, the cable tensioner was found to be at the end of its adjustment range, leaving almost no remaining thread for further tensioning.
Findings
- The primary cause of the accident was the breakage of the rudder control cable at the pulley.
- The cable escaped the pulley groove because the retaining pin was not installed.
- The cable tensioner had reached its maximum limit, preventing further adjustment of the system tension.
- Successive mechanical stresses following the cable's displacement led to the premature wear and eventual rupture of the cable.