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Aviation History
1961
1961 - 1428.PDF
532 FLIGHT, 5 Ocfofor 19( Aviation Electronics 532 Space Saving versus System Maintenance 534 Reliability in Military and Civil Aircraft Electronics 536 JfTiar Price Reliability ? 539 Displays for Modern Radar Data Handling 541 Automatic Check-out 543 77/e Principal Manufacturers RELIABILITY: The three articles which follow all deal with reliability, the factor in electronic equipment which has become more important than ever before. First, an airline development engineer discusses whether the trends in radio equipment packaging: are not in conflict with future airline requirements for maintenance and reliability. Then on page 534, a designer outlines some of the effects on design and manufacture of stringent new military requirements. Finally, on page 536, Marconi describe the practical application of this kind of approach to their new Sixty Series airline radio Space Saving versus System Maintenance By R JON ES IN the rapidly moving world of aviation it is not often possibleto rind time for long-term planning to ensure that movementis in the right direction; yet time can often be spent more profitably in establishing principles of design than in hammeringout the details of individual pieces of hardware. Sometimes the opportunity does occur. For example, some fifteen years agowith the resumption of flying for peaceful purposes, it was important to encourage the development of electronic equipment suitable forcivil operation and designed for convenience of installation and maintenance. In Great Britain the placing of development contractsby the Ministry of Supply was paralleled by the work of an industry committee which, with airline participation, produced the standardracking and unit dimensioning proposals that were eventually recognized by the British Standards Institution as BS.R1. Thedevelopment contract exercise, though it did act as a stimulus, produced little in terms of black boxes on civil aircraft, but thestandardization scheme, being of general rather than particular interest, carrying with it no contractual obligations and exciting norivalry, was highly successful and many aircraft are still flying with installations to this design. During the same period, system characteristics and unit formfactors were being produced in the United States by RTCA. The task of translating performance requirements into black boxes wasthen taken over by ARJNC, an organization sponsored mainly by airlines, which produced the now familiar series of equipmentcharacteristics and the ATR system of unit dimensions. In retro- spect it is easy to see that the activities in the two countries oughtto have been co-ordinated, but it must be remembered that British airframe and equipment manufacturers, as well as the airlines, werecommitted to their own system before developments in the United States received the world-wide publicity they now have throughARINC. It is universally recognized that there is no place in civil aviationfor a variety of standards for civil air transports. British-built aircraft are being purchased by American airlines who require theinstallation of ATR units, and a British operator, when purchasing aircraft in the United States, naturally wishes to have British-maderadio equipment installed. Without standardization, the penalty of doing this is very high indeed, because the amount paid to the USmanufacturer for the equipment installation in each aircraft would be approximately equal to the cost of the British equipment to befitted. But if the equipment conformed to ARINC characteristics it would be installed without charge. This high penalty is justifiedby the airframe manufacturers because of additional engineering investigations and design work and disturbance to their productionlines. It is not attributable to the mere specification of British equipment. Acceptance of ARINC standards for unit dimensionsand external wiring is all that is needed to permit any airline to purchase equipment wherever it chooses. The Aircraft Electronic Engineering Committee which approvecharacteristics before publication by the ARINC secretariat is not an international body and, although it recognizes the world-wideinterest in its activities by having a voting member representing IATA on the Committee, and the special concern of Europeanairlines by inviting a representative of the European Airlines Electronics Committee, these two voices among twenty, with theremaining eighteen speaking for American interests, are of course, unable to affect any issues. Nor does IATA attempt to present aconsolidated airline opinion. There are some who contend that standards which have perforce to be accepted outside the UnitedStates ought to be formally approved by a body more international in its composition and constitution, but it is certain that an inter-national organization could not iron out technical difficulties and produce specifications as expeditiously as does the hard-workingand competent ARINC staff acting on behalf of AEEC. Because all airlines are free to assist in the preparation of charac-teristics and to state their views at AEEC meetings, European air- lines prefer to give recognition to what already exists and theytherefore offer all possible support to the activities of AEEC. They are encouraged to do so by the increasing interest shown in contri-butions from this side of the Atlantic. It is not unreasonable for an airline engineer to believe that thegreat strength of AEEC lies in its being an airline committee as well as a US government representative—the natural instinct ofaircraft and electronic equipment manufacturers is to compete and not to collaborate. Even with the ARINC machinery available,equipment manufacturers still tend to develop their equipment along divergent lines, and it is only when the majority of USairlines have a common interest in buying aircraft with a standard installation that an ARINC characteristic is both produced andused. It is significant that, in the heat of purchasing the Douglas DC-8, the Boeing 707 and other contemporary types, at a timewhen the airlines had to make sure that these aircraft when delivered could be easily fitted with equipment not immediately requiredoperationally, when airframe manufacturers had to know what to build into the aircraft, and when equipment manufacturers hadto know what to produce for later purchase by the airlines, the characteristics produced were those most successful to the extent ofbeing universally accepted. Examples are the characteristics for Doppler, ATC transponder and DME. Characteristics which havefallen by the wayside have been those that have not had behind them the impetus of necessity for action by a majority of Americanairlines and which therefore, from the manufacturers' viewpoint, were not supported by a substantial potential market. If one is not directly involved in AEEC but deeply interested inits activities, it is possible to suggest where effort could best be * BO AC Aircraft Development Section
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