What happened
On March 16, 2015, a Cessna 208B, registration PT-MEA, was performing a routine cargo and passenger flight from Manaus to Maués, Amazonas. The aircraft was carrying two crew members and eight passengers. The flight proceeded normally until the landing at Maués Aerodrome (SWMW).
During the landing roll on runway 19, the aircraft began to yaw sharply to the right. The pilot reported that as the aircraft's speed decreased, the tendency to veer increased. Despite attempts to apply left rudder and differential braking, the crew could not maintain the aircraft within the runway boundaries. To prevent a sudden engine stop, the crew cut the fuel supply. The aircraft exited the runway approximately 330 meters from the touchdown point, traveling 80 meters into a grassy area before coming to a stop. There were no injuries to the ten people on board, though the aircraft sustained light damage.
The investigation
CENIPA investigators determined that the right tire was deflated during the landing roll. The investigation focused on the condition of the tire and the operator's maintenance practices. Analysis of the tire assembly revealed that the inner tube had developed small fissures, which led to the loss of pressure.
Investigators found that the operator had a practice of reusing inner tubes that appeared to be in good condition when replacing tires. The investigation also identified that the specific inner tube involved, along with three others found by the operator, belonged to an older series (marked with green stripes) that had been replaced by a newer, more flexible version (marked with orange stripes). The manufacturer stated that used tubes expand by approximately 25%, making them too large for reuse in new tires, as this causes wrinkling and subsequent failure.
Findings
- The right tire deflated due to small fissures in the inner tube.
- The inner tube was a reused component that had expanded in size during previous use, causing wrinkling and structural weakness.
- The operator's maintenance practice involved reinstalling visually acceptable inner tubes into new tires.
- The specific tubes involved were from an obsolete series with less flexibility than the current standard.
- The instruction to avoid reusing inner tubes was not present in the aircraft's maintenance manual, appearing only in a component manual that the operator did not have access to at the time.
Safety action
It is recommended that the National Civil Aviation Agency (ANAC) work with Cessna Aircraft to evaluate the necessity of including a warning in the C-208 maintenance manuals specifically advising against the reuse of inner tubes during tire changes.