SAIB Warns of Carbon Brake Freezing Problem

 - April 15, 2009, 10:50 AM

The FAA issued a special airworthiness information bulletin (SAIB NM-09-18) last month warning operators of aircraft equipped with carbon disc brakes that absorbed moisture in the carbon discs can freeze and lock wheels. The SAIB resulted from an incident involving a Bombardier Global Express that flew from Van Nuys, Calif., to London Luton Airport. The jet’s carbon discs were exposed to significant rainfall, and it took off 12 hours after the rain ended. The braking materials are porous and can be dried by prolonged exposure to warm, dry conditions, the SAIB explained, “or deliberate braking action during taxi to heat the brakes. If a wet brake is not heated sufficiently to evaporate moisture from the disc surfaces…the brake surfaces may freeze together.” While landing, “the left inboard main landing gear tire suffered a slide-through failure resulting from an initially locked wheel,” causing extensive damage to the flight control system.