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Aviation History
1994
1994 - 0926.PDF
BOEING 777 TECHNICAL UPDATE pany a few headaches. "We developed our own processing-logic chips that were built to our own specification in terms of speed and performance. However, we and our subcontractors encountered some pretty serious ASIC problems and will retrofit final-pass ASICs into the programme," Morrow explains. IMPROVED CHIPS COMING Improved versions of the new chip are being made under subcontract by two California-based companies. LSI Logic makes the digital ASIC, while hybrid ASICs are being made by AMI Gould. Although Morrow says that "...we've al ways it had in the plan that we'd do this final-pass ASIC", he readily admits that the problems were frustrating and could have caused serious delays. "At some stages, we've been barely holding schedule, but we've been support ing Boeing and we've kept them on their functional test plan," says Morrow. "The only headaches we've had were in the scheduling. It's a been a bigger job than we thought, but, with the help of our suppliers, we've pulled it off. In a sense, we've brought our suppliers to the state of the art as we've got there." While Honeywell was giving lessons to its suppliers, it was receiving different tutelage from Boeing. "A big lesson was provided by the concept of service readi ness. The 747-400 was not delivered service-ready. Each aircraft needed a lot of small items worked on after the airline received it. With this and ETOPS [ex tended-range twinjet operations] 'out of the box,' there can't be any serious prob lems. So software and hardware have to be reliable," says Morrow. He continues: "That's the pressure to make sure it's in place by October," when Boeing starts a period of "service-ready" ETOPS testing, in which a 777 will be used on 1,000 cycles to equal one year's worth of real airline-type experience. Other Boeing-led lessons emerged from the construction of the integrated aircraft- systems laboratory (IASL) in Seattle and Cabinets are tested before going to Seattle gives the display unit the capability for anti-aliasing (consistent appearance), symbol prioritisation (one symbol ap pearing in front of another), masking, image fusion and variable line-width drawing. It also incorporates a high speed digital datalink, with data com pression for interfacing to the graphics generator in the aircraft-equipment bay. Other AIMS systems include the cen tral-maintenance function, which re duces the need for "shotgun" mainte nance by improving fault isolation and detection capability. Another system, the aircraft-condition monitoring function, constantly acquires engine and aircraft systems data for use by airline- maintenance planners. The AIMS also includes the digital communications-management function as an access point for digital information and it links airborne and ground-based systems. Another vital element of the AIMS is the flight-management function which builds on systems developed for the 747-400; 757 and 767 and includes thrust management. Many of the systems which interact in AIMS are being developed by Honeywell, including the graphics com puter for the primary flight instruments (the electronic flight-instrument system and the engine-indication and crew- alerting system), and the flight- management system control and display. Honeywell persuaded Boeing to use active-matrix liquid-crystal flat-panel dis plays, but faced a challenging develop ment schedule. "There were compelling reasons for looking at flat-panel displays," says di rector of engineering for display develop ment, Frank Gomer. He cites improved reliability, lower weight and reduced power requirements as the main reasons. "Hybrid CRTs [cathode-ray tubes] would have been used on the 777 — like Flat-panel display can be viewed from acute angles Inside the AIMS those on the 747-400 and 767 — if we hadn't changed their minds," adds staff engineer Richard McCartney. "The big gest challenge was to design flight- worthy displays with very wide viewing angles, both vertically and horizontally. This is also the first commercial applica tion of this technology and the first large-area active-matrix liquid-crystal display," he adds. "We're shooting for a display that's better than CRT quality," says Gomer. The current display can be viewed from all aspects in bright ambient or direct light, making it possible for one crew- member to look across the flightdeck and easily view the PFD screen in front of the other crewmembers' position. "Boeing wanted no fall-off in quality from a hybrid CRT and you've got to applaud them for that, but it does make life difficult for Honeywell. I'm not being crit ical of that, but to mature and perfect that technology right out of the box has been a challenge. The Boeing- Honeywell team is very pleased with the outcome," Gomer says. "So far we're pleased, but we recognise we want to see further improvements be tween now and March 1995," he adds. One area of work remaining, for example, is to eradicate a faint inconsistency in the luminance which mani fests itself as a barely discerni ble border lining the edge of the display. "It's certainly not a certification issue, but it's something we want to solve," says Gomer. An unusual feature of the display unit is a custom graphics-generator chip-set, called the Beamformer. This 24 FLIGHT INTERNATIONAL 6 - 12 April, 1994
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