What happened
On 29 January 2008, a Bombardier BD700 Global Express, registration VP-CRC, arrived at London Luton Airport following a long-range private flight from Van Nuys, California. The aircraft landed on a dry runway without prior incident. However, during the landing roll, the crew identified a loud rumbling noise. This was caused by the left inboard main landing gear tyre suffering a burst following a locked wheel.
As the tyre failed, the rotating wheel caused the tyre carcass and tread to flail violently. This debris struck the aircraft' and caused significant secondary damage, including the destruction of a spray guard, fractures to hydraulic pipes, and damage to the wing's auxiliary spar. The failure also damaged a major wiring loom and impacted the flap drive shaft. Despite the damage, the crew successfully brought the aircraft to a stop using normal braking, and no injuries were reported among the three crew members or one passenger.
The investigation
Investigators examined the aircraft's flight data recorder and the physical condition of the landing gear. They determined that the left inboard wheel had locked upon touchdown and only began to rotate after the tyre had already ruptured. The investigation focused on why the wheel had locked, looking into the history of heavy rainfall at the aircraft's previous location in California.
Analysis of the aircraft's structure revealed that water had likely accumulated on the wing surface and flowed into the wheel bay. The investigators found that the carbon-carbon brake components, which are porous, had absorbed this moisture. During the flight, the high-altitude temperatures reached approximately -25°C, which likely caused the wet brake components to freeze together, resulting in the locked wheel upon landing.
Findings
- The primary cause of the incident was a slide-through tyre failure resulting from a locked wheel.
- Heavy rainfall in Van Nuys led to moisture accumulation on the brakes.
- Sub-zero temperatures during cruise caused the saturated brake stators and rotors to freeze, preventing the wheel from rotating freely at touchdown.
- The flailing tyre material possessed enough mass and kinetic energy to cause extensive damage to hydraulic, electrical, and structural components.
Safety action
- Safety Recommendation 2008-071: Recommended that Bombardier modify the BD700 to prevent water from concentrating on the inboard main-wheel tyres.
- Safety Recommendation 2008-072: Recommended that Bombardier implement structural modifications or use different tyre types to mitigate damage from flailing material.
- Safety Recommendation 2008-073: Recommended that aviation authorities raise awareness regarding the risks of carbon brakes freezing after moisture exposure.