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Aviation History
2004
2004-02 - 0031.PDF
Flight test: Boeing 777-3QOER Massive 777's CCD allows the cursor to be moved GE90-115B directly to the corner of the active display engines and just by touching the corresponding corner 2m-long of the touchpad. raked The overhead panel employs mainly wingtip flush pushbuttons, with system schematics extensions and associated switches logically arranged. distinguish The 777 employs a dark panel philosophy. the -300ER A limited number of critical circuit break- from the ers are located aft of the overhead panel. A basic -300 glareshield-mounted flight-guidance con trol panel and three centre-pedestal con trol display units (CDU) round out the 777's flightdeck. Stretching the 777's fuselage 10.1m (33ft) for the -300 and -300ER variants was challenging. The main landing-gear geom etry was not changed for the- 300 and the additional 4.8m of fuselage aft of the wing limited the body angle attainable on take off rotation. While this no doubt degraded the runway performance of the -300, it still meets all operational requirements. The heavier -300ER was a different mat ter, as a slightly higher take-off attitude was needed to meet operational requirements. The length of the main gear had to be extended, yet it still had to retract into the existing wheel wells. Boeing devised a semi-levered arrangement for the main gear. A hydraulic strut connects the for ward part of the wheel truck to the top of the vertical gear strut. On rotation, the diagonal strut locks in place to keep the gear truck perpendicular to the vertical strut. Instead of rotating about the centre axle, the aircraft now rotates about the aft axle, increasing the apparent height of main gear by around 0.3m. Tailstrike danger As with the stretched Airbus A340-600, tail- strikes are possible, so the control laws of the fly-by-wire 777-300ER in the pitch axis incorporate a tailstrike protection feature. This is available in the normal mode of the fly-by-wire control system and uses up to 10Q nose-down elevator to prevent a tail- strike. Flight-test results show the semi-lev ered gear and tailstrike protection, along with minor improvements to the brakes, have combined to reduce the -300ER's pre dicted take-off field length by 305m. Darcy fired up the tail-mounted auxiliary power unit (APU) in preparation for engine start. On the ground, the APU's primary start mode is via a dedicated battery. In flight it will try to start using pneumatic bleed air if available. The engines were started one at a time using the auto-start feature of the full-authority digital engine controls. Each engine reached an idle N2 of about 69% in less than lmin, with exhaust gas temperature peaking at around 500SC (930°F) - maximum is 750=0. Post-start and pre-taxi checks were easily accomplished. The 777-300ER has two cameras mounted in the horizontal tail and one in the ventral fuselage, designed to assist when taxiing this long aircraft on narrow tarmac. Darcy put the camera display up on the lower centre MFD before starting the taxi. The display has three windows, one for each camera. The two tail- mounted cameras clearly showed each engine and respective main landing-gear wheels, as well as about half the wing. The ventral camera showed the nose gear and www.fliqhtinternational.com FLIGHT INTERNATIONAL 20-26 JANUARY 2004 29
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