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Aviation History
1990
1990 - 2825.PDF
FLIGHT INTERNATIONAL Quadrant House, The Quadrant, Sulton, Surrey SM2 5AS, England FLIGHT TELEPHONE NUMBERS li dialling from outside the United Kingdom prefix numbers with +4481. For example 061-6613321 becomes +44816613321 EDITORIAL ENQUIRIES: 081-6613321 EDITORIAL FAX: 081-6613840 DISPLAY ADVERTISING: 081-661 3315 DISPLAY ADV. FAX: 081-661 8981 CLASSIFIED ADVERTISING: 081-661 6373 CLASSIFIED ADV. FAX: 081-642 4431 TELEX: 892084 REEDBPG EDITOR Allan Winn D81-6B1 3862 DEPUTY EDITOR Grabam Warwick 081 -661 8808 ASSISTANT EDITOR ART AND PRODUCTION Forbes Mutch 081-661 3852 ASSISTANT EDITOR, SPECIAL PROJECTS Tom Hamill 081-661 3096 NEWS EDITOR AnorewChuter 081-661 3843 OPERATIONS EDITOR Mike Gaines 081 -661 8809 TECHNICAL EDITOR Guy Norris 081-661 3835 AIR TRANSPORT EDITOR David Learmount 081 -661 3845 REPORTERS Douglas Barrie 081-6613836 Eric Beech 081-661 3837 Simon Elliott 081-661 3838 Ian Goold 081-661 3834 Alan Postielhwaile 081-661 3839 CHIEF SUB EDITOR Stephen Spark 081 -661 3837 SUB EDITOR Annabel Goddard 081-661 3848 ART EDITOR Coiin Paine 081-661 3850 LAYOUT ARTIST Mike Wells 081-661 3828 TECHNICAL ARTISTS Ira Eplon 081 -661 8054 Tim Hall 081-661 8047 John Marsden 081 -661 8054 EUROPEAN EDITOR Julian Moxon, (32) 2 657 9689 FAX (32) 2657 5260 PHOTOGRAPHER (EUROPE) Mark Wagner (0272) 358200 WASHINGTON BUREAU Kieran Daly (202) 547-2624 FAX (202) 547-5338 LOS ANGELES BUREAU John Bailey (714) 760-6618 FAX (714) 760-6619 PHOTOGRAPHER (USA) Craig Schmitman (213) 391 8981 PARIS CORRESPONDENT Gilbert Sedbon (1) 4825 526' ISRAEL CORRESPONDENT Arie Egozi (3) 9671155 US WEST COAST CORRESPONDENT Norman Lynn (408) 778-0889 FAX (408) 778-9976 SPACEFLIGHT CORRESPONDENT Tim Fumiss 02375 756 CAX 02375 600 DISPLAY ADVERTISEMENT SALES MANAGER Clive Richardson 081-6613315 VICE-PRESIDENT US SALES John Tidy (714) 756-1057 CLASSIFIED ADVERTISEMENT SALES 08' -661 6373 RECRUITMENT 081-6616373 ADVERTISEMENT PRODUCTION Howard Mason 081-6613267 PUBLISHER Gavin Howe For full advertisement sales information see page 84 SUBSCRIPTIONS MANAGER A Walden (0444) 441212 SUBSCRIPTION ENQUIRIES Oaklield House, Perrymounl Road, Haywatds Heath, West Sussex RH16 3DH, England. BACK NUMBERS Limited numbers of RECENT ISSUES ONLY are available at E1.75;copy (CASh WITH OBDER ONLY) from Flight International, Room L531, Quadrant House, The Quaorant. Sutton, Surrey SMZ 5AS. USA NEWSSTAND SALES ENQUIRIES Worldwide Media Service Inc. (fofl-lree), 1 -800-345-6478 fASn Member of the Audit Bureau of Circulation COMMENT Lockerbie's Legacy The report of the British Air Accidents Investigation Branch (AAIB) into the Lockerbie crash of 1988 is significant not so much for establishing the cause of the crash (a bomb) as for triggering a new line of thinking in aircraft design. The AAIB's remit did not include establish ing why and how the bomb got to where it was (that will be the subject of a second fatal accident investigation). It did include establish ing the mechanism by which the aircraft's structure failed following the explosion, and it is from this that some far-reaching proposals (not yet formal recommendation) have come. It is to the design of the fuselage that the AAIB has di rected much of its attention. Fuselage design has, since the adoption of pressurisation, been largely gov erned by factors such as fatigue re sistance and ability to withstand static or slowly cycled pressure. In recent times, more atten tion has been paid to coping with sudden loss of cabin pressure, and the consequent installation of inter-compartment venting systems. What the AAIB has now done is to extend the argument towards coping with rapid rises of pressure within aircraft structures, and to dy namic rather than static pressure loadings. It is in its suggestions that aircraft structures should be designed to tolerate such transients that the AAIB is perhaps setting the aircraft industry on a course of fundamental re-appraisal of design. The concept of damping high-energy pulsed airflow within the aircraft structure is not a difficult one to embrace, nor might it cause too many problems in realisation. Absorbent mate rials fitted in ducts and voids would obviously give weight and cost penalties, and could make aircraft more difficult to build and service. The only real question might be over the effective ness of such materials. Similarly, strengthening cargo containers so that they could contain more of the energy of an explosion before rupturing, and then to rupture in a controlled manner, is not a difficult concept to embrace. Again obviously, the weight and cost penalties of building and carrying stronger containers might make Lhe problem lies in ensuring that the aircraft structure as a whole retains its integrity once such features have been incorporated" such a move unattractive. Less obviously, the ability of a container to tolerate far higher internal loads might lead to a more spectacular form of ultimate failure, but that again could be relatively easy to investigate. In both cases, however, what seems like a practical concept for a large aircraft might prove unacceptable or unworkable on a smaller structure. The concept of providing pressure blow-out panels is—as the AAIB is at pains to point out— a much more difficult one both to grasp and to realise. The principle of a "safety valve" is not in itself difficult to see, nor is that of providing localised strengthening to limit the spread of damage. The prob lem lies in ensuring that the aircraft structure as a whole retains its integrity once such features have been incorporated. It is almost beyond question that such features would be difficult if not impossible to incorporate in ex isting aircraft. It is problematic wheth er they could be in stalled satisfactorily in new-build exam ples of existing designs. It is much more likely that they could incorporated relatively easily in totally new designs. The principal problem is the knock-on effect which such design changes would have on the rest of an aircraft structure. Load paths de signed to skirt intentionally weaker parts of the structure imply greater loads transferred to other parts. Containment of stresses as a means of limiting the spread of damage likewise means a concentration rather than a spread of load. All this means that existing knowledge of stresses and—more importantly—existing fa tigue-testing experience on current aircraft structures could be largely nullified. That is not necessarily a bad thing. Some of the greatest steps forward in structural design have been direct results of changes in the rules or discoveries that existing assumptions were no longer valid. Even should the AAIB's post- Lockerbie suggestions prove to be impractica ble in the short term, they will have a profound effect in the long-term. By even raising some of these concepts, the AAIB has, in effect, rewrit ten the design books. That is a singular achieve ment to draw from a profound tragedy. FLIGHT INTERNATIONAL 19-25 September 1990 5
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