Bell Helicopter (Chalet A43-A44) is here promoting its in-development super medium twin, the Bell 525 Relentless, notably through demonstrations in a traveling simulator. In designing the first-ever fly-by-wire control system for a civil helicopter, the airframer has endeavored to reduce pilot workload, a move to improve safety. The second prototype of the Bell 525 is to start flying by year-end, and letters of intent (LoIs) have been received for about 60 aircraft, mainly for offshore oil-and-gas applications.
Pushing the cyclic stick forward or backward directly controls speed, Mike Bothwell, Bell 525 control law leader, told AIN. The pilot does not have to mentally calculate what the pitch angle should be, relative to the desired speed and the aircraft's weight. In a bank, above 35 knots, the pilot can hit a “re-reference” button, meaning the pilot can release the controls and the aircraft will keep turning at the same bank angle.
To bring the bank angle back to zero, the pilot simply has to get within five-degrees. The digital flight-control system will take care of adjusting to zero.
Discussing takeoff and approach, Bell 525 sales specialist Michael Suldo emphasized the system provides the pilot repeatable maneuvers, whatever the weight.
In case of a double engine failure, the controls give the pilot a head start. The autorotation procedure in a conventional helicopter begins with the pilot lowering the collective pitch to keep the rotor turning fast enough. If the pilot fails to do so within a handful of seconds, rotor rpm may drop dangerously to 80 percent. At this point, the pilot may never get the required 100 percent back, meaning the engine failure will translate into a serious accident. The 525’s flight controls automatically lower the collective pitch after a double engine failure. It does so immediately, ensuring rotor rpm will remain at or above 100 percent.
Bell has worked with the FAA to develop a fly-by-wire certification basis, as no helicopter has yet been certified with a computer in the flight control loop. The rulemaking effort started for the AW609 Tiltrotor (Bell was involved in the program, at the time). But the Bell 525 is likely to enter service in 2017, before the AW609.
The Bell 525 sells for $20- to $21 million in a basic configuration, Suldo said. He expressed hope the oil-and-gas market will have recovered by 2017. The LoIs will then be more easily turned into firm orders.