Carbon Brakes and Slush

Carbon Brakes and Slush


During winter operations, the aircraft brakes and the open wheel well/bay may be exposed to alkali-organic salt runway de/anti-icing substances during taxi, take-off and landing. A slush mixture of snow and alkali-organic salt de/anti-icing substances could freeze onto the landing gear and the interior of the wheel well/bays. If, after landing gear retraction, such frozen deposits begin to melt, the resulting liquid is liable to flow into the core of the brake unit, If the brake discs are made of carbon rather than steel, the presence of the alkali-organic salt creates a catalytic condition which lowers the oxidation temperature of the carbon and leads to structural deterioration of the carbon disc material so that efficiency and ultimately the service life of the brake unit is reduced. Aircraft Operators need to consider whether any special inspections are appropriate in the light of their operations.

Related A&I

On 1 February 2015, a Bombardier CRJ 1000 departed from Pamplona with slush likely to have been in excess of the regulatory maximum depth on the runway. On landing at Madrid, the normal operation of the brake units was compromised by ice and one tyre burst damaging surrounding components and leaving debris on the runway, and the other tyre was slow to spin up and sustained a serious flat spot. The Investigation concluded that the Pamplona apron, taxiway and runway had not been properly cleared of frozen deposits and that the flight crew had not followed procedures appropriate for the prevailing conditions.

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