Boeing has completed tests of an improved carbon brake system for the 767, which is expected to increase brake life, produce smoother operation and be quieter than the existing unit.

The improved system, developed by AlliedSignal Bendix, is a step beyond the advanced carbon brake system used on the 777, says 767 chief project engineer Dave Anderson. "It's the first time we've made a wholesale change in the carbon material," adds Anderson.

The new brakes are configured to fit in the existing assembly and consist of eight stacks with four rotor brakes in each stack. Using a newly built 767-300ER on loan from American Airlines, the brakes underwent wet runway tests followed by 100% energy rejected take-off (RTO) tests. The latter involved RTOs at maximum take-off weights of 187,000kg (412,000lb) with one new brake and seven 100%-worn brakes in each stack. Take-offs were rejected at speeds of around 170kt (315km/h) and the aircraft brought to a full stop with no reverse thrust.

Boeing plans to certificate the system and begin introduction on new build 767s from next January. "We will also offer retrofit kits for availability around the same time," says Anderson. The current brakes are good for between 1,500 and 2,500 landings per set, and Boeing believes the improvements could raise this threshold to about 3,000.

In a related development, Boeing plans to hold its first critical design review with Messier Bugatti "in a few months" on an alternate brake system for the 767. "Airlines have pressed us for a second source on consumables," says Anderson. The French unit will be available around mid-1999.

Source: Flight International