Electric brake technology put through paces on aircraft

11.04.2008

Messier-Bugatti has just carried out the first electric brake tests on an aircraft, to move one step closer to the future generation of more electrical aircraft.

© AIRBUS 2008/ S.Ognier

The tests carried out on February 13 on an Airbus A340-600 will go down in the history of modern aviation, since it was the first time that a commercial aircraft has braked using entirely electrically actuated brakes. These tests mark an important stage for Airbus and Messier-Bugatti in the preparation of future generations of aircraft. The aircraft manufacturer and the SAFRAN Group have been working jointly on this since 2003 as part of the EABS (Electrically Actuated Braking System) demonstration program. The objective of this program has been to evaluate what advantages electrically actuated braking technology offers when compared to the current hydraulically actuated brake technologies. This flight testing campaign consisted of landings with automatic braking and aborted take-offs (RTO)*.

For Messier-Bugatti, this procedure is part and parcel of its permanent innovation drive. The company had already made its mark on the world of aviation with the first mass production of carbon brake disks in 1985. This latest major technological innovation is also representative of the revolution taking place in the aeronautical industry, where it is already taken for granted that the airplane of the future will be “all-electric”. The current trend, therefore, is to eliminate progressively every form of power other than electrical power onboard aircraft (with the exception of the engines, of course).

Weight, fuel consumption, maintenance: considerable benefits

Until today, airliner brakes have been actuated by means of a hydraulic system. An electrically-controlled braking system offers many advantages by comparison, and a number of positive spin-offs as a result: shorter delivery schedules, weight savings, reduced fuel consumption, reduced maintenance costs and improved aircraft availability.

Electrically actuated braking simplifies the assembly operations on the aircraft manufacturer’s production line, so offering time savings in the manufacturing process and hence, as a consequence, shortened delivery schedules. In addition, the electrical brakes on an “all-electrical” aircraft (i.e.: one on which all the hydraulics and associated pipelines have been eliminated) contribute to aircraft weight savings, which in turn lead to reduced fuel consumption.

Another positive point for the aircraft operators is that an electrical fault does not entail immobilization of the aircraft, as a hydraulics failure would. With electrical brakes, a compensation mechanism links up the actuators to a self-diagnostic system. The components can operate in independent and modular fashion, with the control system maintaining braking system efficiency and guaranteeing its performance level even in the event of a component failure. This allows the aircraft availability rate to be significantly increased.

Maintenance costs can also be reduced, since first-level operations are facilitated (no hydraulic system purging needed). The end of hydraulics will also mean the end of the consequences arising from hydraulic system leaks; one element of the fire risk will thus be confined to history. Finally, thanks to electronics, the pilot is able to monitor brake wear and tear directly. Here again, the airline companies can only be winners in terms of operational efficiency.

Having passed this first test in use on a commercial aircraft at the start of 2008 with flying colors, the electrical brake looks to have a promising future ahead of it.

* Rejected Take Off: the most demanding of brake tests. It involves braking a fully-laden aircraft (with passengers and fuel) at full speed at the end of the runway, at the moment of take-off and over a reduced distance

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