What happened
On 13 May 2001, a Socata TB9, registration G-BKIB, was performing a private flight landing at Hawarden Airport, Wales. The weather conditions were good, with a light wind blowing from the left. According to a witness, the aircraft touched down normally on the centerline within the designated touchdown zone of Runway 05.
Immediately following the mainwheel touchdown, the aircraft began an uncontrolled turn to the left. The pilot attempted to counteract this movement by applying the right brake pedal, but the aircraft continued to veer, eventually leaving the tarmac runway and crossing onto the grass verge. The aircraft came to a stop at a heading approximately 120 degrees left of the runway centerline. During the excursion, the right wing tip scraped the ground, causing minor damage to the nosewheel fairing.
There were no injuries to the pilot or the two passengers on board.
The investigation
Following the incident, the aircraft was moved to a maintenance area. The Chief Flying Instructor of the local flying school, who was at the controls, noted that the left brake was both audible and palpable in its binding. He reported that significant effort was required to maintain a straight course, though the binding had eased significantly by the time the aircraft reached the apron.
Investigators noted that this was the second instance where the aircraft had veered left during landing. A previous similar event had been attributed to accidental brake application because no mechanical fault was identified at that time. However, during this investigation, the brake assembly was dismantled for a thorough inspection. While the brake pads and disc were within acceptable wear limits, investigators found a slight fluid seepage. To address this, the slave cylinder 'O' ring seal was replaced.
Findings
- The primary cause of the runway excursion was a binding left brake.
- A slight fluid seepage was identified within the brake assembly.
- The aircraft's nosewheel fairing sustained minor damage during the event.