What happened
On March 30, 2011, a Cessna S550, registration PT-OSM, was performing a passenger flight from Salvador, BA, to Brasília, DF. During the landing phase on runway 11L at Brasília International Airport (SBBR), the right main landing gear wheel locked up. This sudden lock-up caused the right tire to burst and triggered a significant rightward yaw.
The pilot attempted to correct the deviation using rudder pedals, braking, and differential reverse thrust, but the aircraft could not be maintained on the runway centerline. The aircraft subsequently veered off the runway and came to a stop in the adjacent grassy area. All five occupants—two crew members and three passengers—were unharmed, though the aircraft sustained damage to the right tire, the wheel, and the brake assembly.
The investigation
CENIPA investigators examined the runway markings, which showed a continuous rubber skid mark leading from the pavement into the grass. Analysis of the damaged tire revealed two distinct wear patterns: one area of uniform abrasion consistent with high-friction grinding, and a second area where the tire sidewalls had worn down to the point of contacting the pavement, indicating a loss of pressure following the initial burst.
Technical inspections were conducted on the braking system. The Electronic Control Box and the brake assembly were tested, and specialized non-destructive testing (NDT) was performed by US-based maintenance organizations on the transducers and brake components. These tests found no functional abnormalities or discrepancies in the anti-skid system or the mechanical brake components.
Findings
- The primary cause of the excursion was the locking of the right main landing gear wheel.
- An inadvertent application of the brake pedals by one of the pilots during touchdown remains a possible contributing factor, as the anti-skid system was found to be fully functional.
- The investigation also considered the possibility of an undetected tire defect causing pressure loss during flight, or a potential intermittent failure in the anti-skid system, though no evidence was found to confirm these hypotheses.
- During the investigation, it was noted that the wiring harness for the left brake assembly was damaged; subsequently, the wiring and transducers for both brake assemblies were replaced.