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Aviation History
1986
1986 - 0963.PDF
taking place in the autopilot. On the MD- 88 the autopilot will pass this digital infor mation on to the Sperry flight manage ment system, which will in turn pass lateral and vertical navigation commands back to the autopilot and autothrottle. Although the Efis will be available for retrofit to other members of the MD-80 family, McDonnell Douglas does not intend to offer the flight management system on its own, as its capability would be compromised by the lack of an Efis map display. The Efis-equipped aircraft will become available early in 1987, and the all-up MD-88 late that year. Windshear guid ance capability is scheduled to become available in mid-1988, and will comprise a separate computer linked to existing sensors. In designing the electronic cockpit for the MD-11, McDonnell Douglas' updated, extended-range DC-10 now on offer to airlines, the company had the additional task over that faced with the MD-88 of simplifying and reducing workload to cut the flightdeck crew from three to two, as Boeing did with the 747-400. MDC did not want to modify DC-10 systems unnecessarily and so forfeit 15 years of flight experience with some 400 aircraft. At the same time the company wanted to take advantage of technology that had become available since the DC-10 was designed. The result, McDonnell Douglas believes, is the best of both worlds: the most modern cockpit in a proven airframe. The company has elected to change systems only where it will reduce crew workload or improve maintainability, and to leave unchanged systems that have proved reliable and where no new tech nology has emerged. The reduction in workload has therefore been achieved largely through automation. McDonnell Douglas describes its philosophy as "one step beyond Eicas". Instead of displaying the corrective actions which the pilot should take in the event of a malfunction, the system auto matically copes with the failure by follow ing a defined procedure based on MDC's long experience with the aircraft. This automatic control resides with the aircraft system control—five boxes in the avionics bay, one each for the hydraulic, electric, pneumatic, fuel, and miscel laneous systems. Each box contains the logic and switching for system control and interfaces with the relevant overhead panel—MDC calls them smart panels— which takes the place of the flight engineer. The automatic system is dual- redundant. Each box is dual-channel, with two processors, plus a third responsible for monitoring the automatic system. After a first failure the system stays automatic. After a second failure the system reverts to manual control via the overhead panel. MDC has automated only what it makes sense to automate. The automatic system is not allowed to dump fuel, for example. The pilot monitors the performance of the aircraft system control on his systems display, part of the six-CRT Efis being developed by Sperry for the MD-11. The Efis uses large, 8in-square CRTs. Side by side in front of each pilot are the primary flight and navigation displays. Between the pilots is the engine instrument display, and below that the systems monitor. There are three display electronic units, any one of which can drive all six CRTs. There is also some symbol generation capability in the displays themselves, with backup direct-line inputs from a keying system. Fewer lights, switches and gauges The aircraft system control, overhead smart panels, and system monitor all contribute to a reduction in lights, switches, and gauges from 1,000 in the DC-10 to around 300 in the MD-11, says McDonnell Douglas. On the pedestal between the pilots are three multifunction control display units (MCDUs). The forward two interface with the flight management system and have backup manual tuning capability for radio navigation aids. The third MCDU is used by the ground crew for maintenance, but has backup navigation capability in case both flight management systems fail in flight. The flight management and flight control systems are separate computers, but are functionally integrated, says MDC. Vertical navigation capability resides in the flight management system, with a backup in the flight control system, to simplify the pilot interface. McDonnell Douglas hopes to launch development of the MD- 11 by the middle of this year, although it has yet to secure a customer. To protect the first flight date of January 1989, however, engineering authority to proceed has already been given. Certification and customer delivery are scheduled for December 1989. Sperry is working with MDC on the four packages which go to make up the MD-11 cockpit—flight management system, flight control system, Efis, and aircraft system control. The basic cockpit design is frozen, and a working group has been formed with interested airlines to fine-tune the design. Two cockpit simu lators are planned, one at MDC and one at i Sperry. D i FLIGHT INTERNATIONAL, 26 April 1986 33
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