Another Gulfstream InnovationBy J. Mac McClellan, EAA Editor-at-Large
The G50 has accomplished many things during its initial testing, including setting a speed record. Electric primary flight controls are the newest feature on this ultra-long-range aircraft.
January 13, 2011 — Gulfstream is the first business jet manufacturer to fly using electric-powered primary flight controls. The successful tests were conducted in the ultra-long-range G650 that is in developmental flight testing with FAA certification expected later this year.
The G650, which has a very large cabin as do all larger newly designed jets, uses fly-by-wire (FBW) technology to link the pilot controls in the cockpit to the flight control surfaces on the airplane. One of the major safety benefits of FBW is a level of redundancy that cannot be achieved with conventional cables, push rods, and bell cranks. To assure continuous control functioning, at least three independent systems are required. Other jets use multiple hydraulic systems to move the control surfaces, but Gulfstream is the first to add electrically actuated controls on top of dual independent hydraulic systems.
Under normal conditions the FBW commands from the pilots or autopilot will cause hydraulic actuators to move the ailerons, elevators, rudder, and spoilers. But if in some extremely rare failure event both independent hydraulic systems are breached, the electric control actuators take over and provide complete and positive flight control.
During the first test of the electric control system Gulfstream test pilots flew at speeds ranging from just above stall to normal high-speed cruise at 45,000 feet. They also made several landings using only the electric-powered controls. The system performed so well the pilots couldn't really tell the difference between the normal hydraulic control actuation and the backup electrically powered system.
In view of the severe widespread damage recently caused by the uncontained engine failure on a giant Airbus A380, it's impossible to say that the worst can't actually happen. Gulfstream is planning for the worst case, no matter how unlikely it may be. The total independence of both power source and operating technology for the electric control actuations gives the G650 a level of redundancy that is new and innovative.