Dunlop Aerospace Braking Systems, at Paris as part of the Meggitt group (Hall 2B, L13), is showing how its new range of advanced anti-oxidant treatments can be highly effective in protecting the carbon-carbon composites used for the heat packs of aircraft brakes, significantly extending service life.
Two treatments from the new range have been applied to the non-rubbed surfaces of the stators and rotors on the BAE 146/AVRO RJ brake. Dunlop says this has allowed the brakes to operate for much longer under difficult braking conditions that are aggravated by aggressive runway and aeroplane de-icers containing catalysts which promote oxidation.
As a result, inspection intervals have been extended and average brake life across the fleet is considerably longer, although the improvement varies from case to case, depending on the aircraft's operating cycle.
Carbon oxidation is an "activated process" in which the rate of oxidation climbs exponentially with temperature, becoming very pronounced above 500°C, while aircraft brakes can get up to between 550°C and 650°C during a landing.
The Dunlop Aerospace treatments achieve their effect in two ways. Below 520°C, inhibitors in the treatments slow the reaction of the carbon with oxygen. At higher temperatures, barrier-forming species within the Dunlop anti-oxidants react with the surrounding oxygen to form a coating that prevents the ingress of oxygen into the composite.
Anti-oxidants
Dunlop says its anti-oxidants will be particularly valuable in counteracting the oxidising effects of the new family of de-icing and anti-icing products based on carboxylic acid salts (potassium acetate, sodium formate etc) widely used in European airports since the mid-1990s. They will also extend brake service life even for aircraft operating in territories that never experience severe winter weather, or where the traditional glycol and urea-based de-icers are used.
Toby Hutton, manager of Carbon Technology at Dunlop Aerospace Braking Systems, says: "Our new anti-oxidants represent a significant advance in brake design and maintainability.
"We believe they will have many applications elsewhere, not only in other high-wing aircraft but particularly with fuselage mounted undercarriages, where the nosewheel sprays water and de-icer on to the rear wheel and brakes."
Two treatments from the new range have been applied to the non-rubbed surfaces of the stators and rotors on the BAE 146/AVRO RJ brake. Dunlop says this has allowed the brakes to operate for much longer under difficult braking conditions that are aggravated by aggressive runway and aeroplane de-icers containing catalysts which promote oxidation.
As a result, inspection intervals have been extended and average brake life across the fleet is considerably longer, although the improvement varies from case to case, depending on the aircraft's operating cycle.
Carbon oxidation is an "activated process" in which the rate of oxidation climbs exponentially with temperature, becoming very pronounced above 500°C, while aircraft brakes can get up to between 550°C and 650°C during a landing.
The Dunlop Aerospace treatments achieve their effect in two ways. Below 520°C, inhibitors in the treatments slow the reaction of the carbon with oxygen. At higher temperatures, barrier-forming species within the Dunlop anti-oxidants react with the surrounding oxygen to form a coating that prevents the ingress of oxygen into the composite.
Anti-oxidants
Dunlop says its anti-oxidants will be particularly valuable in counteracting the oxidising effects of the new family of de-icing and anti-icing products based on carboxylic acid salts (potassium acetate, sodium formate etc) widely used in European airports since the mid-1990s. They will also extend brake service life even for aircraft operating in territories that never experience severe winter weather, or where the traditional glycol and urea-based de-icers are used.
Toby Hutton, manager of Carbon Technology at Dunlop Aerospace Braking Systems, says: "Our new anti-oxidants represent a significant advance in brake design and maintainability.
"We believe they will have many applications elsewhere, not only in other high-wing aircraft but particularly with fuselage mounted undercarriages, where the nosewheel sprays water and de-icer on to the rear wheel and brakes."
Source: Flight Daily News
