Recent G650 flight first ever to use electrically powered backup controls

Gulfstream Aerospace test pilots and flight-test engineers recently made business-aviation history when they flew the Savannah-built Gulfstream G650 flight-test aircraft for the first time using only an electrically powered, fly-by-wire backup flight-control system.

The plane, Gulfstream’s Serial Number 6001, flew for a total of 3 hours and 33 minutes on Dec. 21.

Test pilots Jake Howard and Gary Freeman, along with flight-test engineers Bill Osborne and Nathaniel Rutland, evaluated the fly-by-wire system in electric backup actuation mode for 2 hours and 20 minutes of the flight, performing five landings with the backup system engaged.

“The system performed flawlessly,” said Pres Henne, senior vice president for programs, engineering and test at Gulfstream.

“There was no difference in handling qualities between the electrically and hydraulically powered modes.”

Said test pilot Freeman: “It flew so well that unless pilots were told they were in backup actuation mode I don’t think they would notice.”

Typically, fly-by-wire uses a third hydraulic system to provide redundancy in the event of a dual hydraulic system failure.

However, Gulfstream’s fly-by-wire architecture uses electric backup hydraulic actuators – electrically controlled actuators that are primarily hydraulically powered but offer electric power as a backup. A self-contained hydraulic reservoir and motor pump allow full operation should hydraulic loss occur.

The system provides enhanced safety and aircraft availability because of the two different power sources.

The self-contained actuators also offer an advantage following extremely rare failure scenarios, such as a rotor burst, which occurs when an engine fails, resulting in the high-energy release of rotor fragments that can damage critical systems.

The December flight tested the electric backup handling qualities on the plane’s three axes: pitch, roll and yaw. Flap settings were tested at 10,000 feet at speeds ranging from near stall to full speed, and cruise configurations were evaluated at a variety of altitudes ranging from 28,000 feet to 45,000 feet.

The pilots also initiated an emergency descent from 45,000 feet to 25,000 feet and evaluated handling qualities in the landing configuration by making multiple offset approaches at Brunswick Golden Isles Airport.

ABOUT THE G650
The new flagship in a line of Gulfstream business jets, the ultra-large-cabin, ultra-high speed G650 is designed to fly faster and farther than any traditional business aircraft. Capable of carrying eight passengers and a crew of four on nonstop legs of 7,000 nautical miles, it can link Dubai with New York and London with Buenos Aires. Equipped with powerful Rolls-Royce BR725 engines, the G650 will cover shorter distances at a speed of Mach 0.925, just shy of the speed of sound.

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http://savannahnow.com/exchange/2011-01-19/gulfstream-tests-unique-fly-wire-system