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Aviation History
1997
1997 - 3327.PDF
BOEING 777 300 Boeing 777-300 ground-manoeuvre camera-system fields of view It consists of three cameras, one mounted in the leading edge of each horizontal stabiliser and the third beneath the forward cargo bay aft of the nose leg. The 777-300 is the first aircraft to be fitted with such a system. In another throw-back to the 747 days, Boeing built a large ground rig called the LAGOS (large-aircraft ground-operating sys tem) to simulate ground handling. Pilots from its airline workinggroup were invited to trundle around the Everett ramp in it and make com ments. Unlike those with "WaddelFs Wagon" (named after the 747 project pilot Jack Waddell), the trials involving the LAC JOS proved that a ground-camera system was a good idea. It was considered necessary mainly because of the extended wheelbase of the new stretch, now 31.2m compared with 25.9m for the -200, making it the largest wheelbase of any aircraft in the world. The front camera has a horizontal field of view YoV) of 89.4° in azimuth and 30.4° verti cally, although the vertical EoV seen on the dis play unit on the flightdeck covers 18.6°. Similarly, the tail-mounted cameras can cover an F6V of 26.4° with electronic panning, and show a standard 18.6° vertical EoV on the dis play unit. Changes in stabiliser trim-setting (0' to -2°) can change the camera's sweep angle by up to 3.5' in horizontal coverage and 7 in the vertical plane. The nose-gear viewingcamera is mounted in a sealed unit between fuselage stations 592 and 613. The unit's main connection to the aircraft structure is surrounded by a stand-pipe designed to stop moisture (from condensation within the belly) from dripping down into the camera housing. The main-gear viewing cam eras in the tail are removable from the leading edge as single line-replaceable units. The units are sealed for moisture control and to prevent anything in the electronics acting as a potential ignition source. The front of each camera is protected by a sapphire window with a conduc tive coating to keep it from fogging up. The camera images are presented on a T- shaped split screen, with the nose gear shown across the top of theT and the main gears shown on the bottom left and right. The picture can be shown on any three of the 777's six Honeywell flat-panel displays. Those allocated to the GMCS include the two inboard navigation dis plays and the main multi-function display below the EICAS. Camera lights, needed to help illu minate the ground for night operations, are con trol led by a new panel switch on the glareshield. Another new feature, and one of the most novel engineering aspects of the -300, is the unusual over-wing escape slide. This is pack aged into a container in the aft fairing beside the new Section 44 door. Described by Tomkins as a "pretty unique and invoked design", the slide is deployed aft and above the wing. .As it inflates, Big brother: The first 777-300 towers over a 7J7 the slide forms up to the door while another part deploys and slides down to the ground. The combined slide therefore forms an angle as it is deployed, and is fitted with a rail on the outside of the curve. Integral lights are built into the slide, and additional lights are mounted in the aircraft to illuminate the entire area. MANUFACTURING CHALLENGE When it launched the 777-300 on 26 June, 1995, Boeing set itself the ambitious target of getting the aircraft into service with launch cus tomer Cathay Pacific some 32 months after the firm configuration was set in October 1995. The 2 5 % product-definition stage was reached successfully in June 1996, allowing the release of major parts, plans and tools for production. Detailed fabrication, meanwhile, began in February 1996, with the two efforts, which Boeing terms "define" and "build", culminating in the start of major assembly in March 1997. The true length of the -300 became apparent to onlookers for the first time at 0130 on the morning of 21 July this year, when the final body-join of the first aircraft, WB501, was com pleted. At 73.8m in overall length, the -300 is 3.4m longer than the 747. "The join came together just like the first -200," says Liz Otis, directorofthe 777 manufacturing business unit. The production challenge was compounded by the fact that, at the same time, Boeing was step ping up 777 production. The first -300, line number 94, was rolled out at Everett on 8 September and prepared for flight tests, which began with a "flawless" 4h 6min sortie on 16 October. The main focus of the test effort was to evaluate the effects of the stretch on overall handling, including ground operations and use of the cameras. The test team predicted that the -300 would be more controllable in yaw because of the larg er tail-moment arm,but that pitch control could be adversely affected by the greater inertia. "Drag will be higher and there will be less flow down on to the tail," says Boeing flight-test chief pilot JohnCashman, who was in the right-hand seat for the maiden flight. The team was also on the alert for signs of increased susceptibility to "airplane-pilot coupling" in pitch, formerly known as pilot-induced oscillation. "It could be worse, depending on the control response," says Cashman, who expects the-300's handlingqual- ities to be on a par with those of the -200, thanks largely to the adjustable gains of the digital flight-control system. Although the test fleet of five 777-300swill be used for plenty of runway work, some of the more daring exploits of the -200 test pro gramme will not be repeated. Boeing 777 pro gramme chief pilot Frank Santoni says: "We won't have to do maximum brake-energy tests and \\„ [minimum unstick speed]. You might have thought we would have needed to perform these, but we can do it by analysis. We extrapo late the results from the -200 \\u and rejected- take-off tests which were done at 287,200kg • FLIGHT INTERNATIONAL 3 - 9 December 1997 39
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