Graham Warwick/MONTREAL

Bombardier is close to selecting a partner for a programme to demonstrate fly-by-wire flight-control technology for use in future business and regional aircraft. Four unidentified companies have been shortlisted for the role of prime vendor in the Canadian company's four-year active-control-technology (ACT) demonstration programme.

An agreement is expected this month, says Canadair vice-president of engineering John Taylor. The companies shortlisted have either developed commercial fly-by-wire systems previously, "-or want to", he says. "We would like to team with somebody with experience," Taylor adds. Agreement has been reached already to co-operate with Canada's National Research Council, which has experience with fly-by-wire systems.

The ACT programme was launched early in 1996, says project leader Guy Bernard. Bombardier's Canadair Challenger 601 testbed will be modified with a prototype fly-by-wire system for flight tests beginning late in 1998. The company plans to have the specifications for a production fly-by- wire system available by the end of 1999, although Taylor cautions that Bombardier's new mid-size business jet, now in advanced design and planned to enter service in 2002, "-will not be fly-by-wire, for economic reasons". The company does see cost benefits for larger aircraft, Bernard says.

The Challenger testbed, aircraft 3991, will be fitted with a fly-by-wire system which will drive the flight-control surfaces through uprated autopilot servos. Flight tests will evaluate control-wheel and sidestick inceptors, says Bernard. Conventional mechanical controls will be retained, for safety. The programme will allow Bombardier to evaluate its chosen fly-by-wire architecture.

Taylor says that issues to be resolved include the choice between what he describes as "Airbus or Boeing philosophies". Bernard says that the company favours the Boeing philosophy, which he describes as "-keeping the pilot in the loop". He explains: "It is our intention to aid, not replace the pilot. We want to help the pilot's understanding and improve his situational awareness."

Bombardier evaluated fly-by-wire for the Global Express long-range business jet, but rejected it for two reasons, Taylor says. "We did not get enough customer input wanting fly-by-wire, and we could not afford to develop the technology while developing the aircraft."

Taylor says that it is important for the aircraft manufacturer to retain responsibility for development of flight-control laws. "They define the aircraft personality, its operating philosophy and its operating limits. We want to be in the driving seat," he says. "Fly-by-wire is not an off-the-shelf commodity. It's too much part of the aircraft," he maintains.

Source: Flight International