Andrew Doyle/PARIS

MESSIER-BUGATTI believes that, within four years, it will be able to offer aircraft carbon brakes, which are as cheap to operate as their equivalent steel brakes, according to chairman and chief executive Yves Leclere.

"We will match the direct operating costs [DOCs] of steel brakes by the turn of the century," says Leclere, who reveals that the state-owned French company is working on a range of new technologies to achieve this goal.

Current-generation carbon brakes are considerably lighter than equivalent steel brakes, but less durable and more expensive to make. They also suffer from oxidisation effects, which force operating temperatures to be reduced.

As a result, carbon brakes are widely used on long-haul aircraft, where the fuel saving justifies the higher DOCs of the brakes, but they are less popular on short-haul aircraft, which perform a high number of flight cycles.

Messier-Bugatti, like other manufacturers such as the UK's Dunlop Aviation, is working on so-called carbon-carbon composite materials to improve the durability and high-temperature performance of carbon brakes.

By making use of carbon for both the matrix and the fibre reinforcements, the manufacturers hope that carbon-carbon composites can overcome the strength and brittleness limitations of conventional carbon brakes, without degrading their thermal properties.

Other studies are focused on how, to reduce excessive brake wear, during the taxi-out phase during, which around 70% of total brake wear occurs. This is because wear is disproportionately high when carbon brakes are cold. Messier-Bugatti is considering the use of a "selective-braking" system, where only certain brakes would be used during taxi-out.

Messier-Bugatti's third-generation Sepcarb III brake will enter service on Swissair's Airbus A319s this month and then be retrofitted on A320s, offering maintenance costs claimed to be "close to those of conventional steel brakes".

Source: Flight International