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Aviation History
1991
1991 - 2437.PDF
INTERNATIONAL Editorial Enquiries +44 (81) 661 3842 Editorial Fax +44 (81) 661 3840 Display Advertising +44 (81) 661 3315 Display Advertising Fax +44 (81) 661 8981 Classified Advertising +44 (81) 661 6373 Classified Advertising Fax +44 (81) 642 4431 Telex 892084 REEDBP G Subscriptions +44 (81) 649 7271 Back issues (recent copies only) +44 (81) 661 3315 Picture Library +44 (81) 661 3427 Flight Directories +44 (707) 46952 USA Newstrade Sales Enquiries 800 345 6478 LONDON Quadrant House, The Quadrant, Sutton, Surrey SM2 5AS, UK Editor Allan Winn +44 (81) 661 3882 Editor's PA Jacqueline Wotsley +44 (81) 661 3882 Deputy Editor Forbes Mutch +44 (81) 661 3852 News Editor Andrew Chuier +44 (81) 661 3843 Features Editor David Learmouni +44 (81) 661 3845 Military Editor Mike Gaines +44 (81) 661 8809 Air Transport Editor Ian Goold +44 (81) 661 3834 Technology Editor Simon Elliott +44 (81) 661 3838 Databases Editor Tom Hamill +44 (81) 661 3096 Editorial Assistant Kate Sarsfield +44 (81) 661 3842 Art Editor Colin Paine +44 (81) 661 3850 Layout Artist Mike Wells +44 (81) 661 3828 Sub-editor Annabel Goddard +44 (81) 661 3848 Layout Sub-editor Jenny Long +44 (81) 661 384? Technical Artist Tim Hall +44 (81) 661 8047 Technical Artist David Hatchard +44 (81) 661 8047 Technical Artist John Marsden +44 (81) 661 8054 Spaceflight Correspondent Tim Furniss +44 (237) 451756 Fax +44 (237) 451600 Photographer (Europe) Mark Wagner +44 (272) 358200 Fax +44 (272) 358290 Display Advertisement Sales Sales Manager Clive Richardson +44 (81) 661 3315 Assistant Sales Manager Nick Wilcox +44 (81) 6613892 Senior Sales Executive Janice Lowe +44 (81) 661 3316 Advertisement production Howard Mason +44 (81) 661 3267 EUROPE/MIDDLE EAST European Editor (Brussels) Julian (Axon +32 (2) 657 9689 Fax +32 (2) 657 5260 Munich Correspondent Douglas Barrie +49 (89) 689 1041 Fax +49 (89) 689 1045 +33 (1) 4825 5261 +972 (3) 967 1155 Paris Correspondent Gilbert Sedbon Israel Correspondent Arie Egozi Sales Director (France) Pierre Mussard +33 (1) 42771417 Representative (Italy) flomano Ferrario +39 (2) 58084 302 AMERICAS American Editor Graham Warwick +1 (404) 587 2927 Fax +1 (404) 594 1534 Washington Correspondent Kieran Daly +1 (703) 836 7443 Fax +1 (703) 836 7446 USA West Coast Correspondent (Us Angeles) Guy Norris +1 (714) 252 8971 Fax +1 (714) 252 8972 Photographer (USA) Craig Schmitman +1 (213) 391 8981 Fax +1 (213) 391 8492 President RBP (USA) Ray Barnes +1 (212) 867 2080 Traffic Manager JoAnn Lapp +1 (212) 867 2080 Fax +1 (212) 687 6604 Vice President US Sales John Tidy +1 (714) 756 1057 Fax +1 (714) 756 2514 Sales Director (Mid West and Canada) Gene Glendinning +1 (708) 635 9920 Fax +1 (708) 635 0602 Sales Director (East Coast) Robert Hancock +1 (703) 836 7444 Fax +1 (703) 836 7446 Business Development Director Sheera Robbins +1 (703) 836 7444 Fax +1 (703) 836 7446 ASIA/PACIFIC Asian Editor (Singapore) John Bailey +65 226 3188 Fax +65 227 1769 Australian Correspondent Paul Phelan +61 (70) 532 791 Fax +61 (70) 532 791 Sales Director Mike Hancock (Singapore) +65 226 3188 Sales Executive Fiona Bartholomeusz +65 226 3188 Fax +65 223 6960 Regional Representative (Japan) -Toshiaki Nakagawa +81 (3) 3234 2161 Fax +81 (3) 3234 1143 Publisher Les Edwards +44 (81) 661 3436 For full advertisement information see page 52. Member of the Audit Bureau ol Circulation COMMENT VOLTE-FACE OR VOLTE-FARCE? The best thing to do about a mistake is to admit to it, and then to correct it if it is not too late. The US Federal Aviation Administration (FAA) has just done so, to its eventual credit, over the question of thrust reversers in the wake of the Lauda Air accident. It is to be hoped the FAA has acted in time to ensure that there are no more cata strophic accidents caused by unplanned thrust- reverser deployment. Whether or not it acted in time to salvage its reputation is another matter. In early August, the FAA informed operators that, provided the mandated airworthiness tests and inspections had been properly conducted, it was "...confident in the ~~ safety" of the Boeing 767 fitted with Pratt & Whitney PW4000 en gines (the type fitted to the Lauda aircraft). Within a week it had issued an airworthiness directive (AD) calling for thrust reversers to be de-activated on all but early 767s which had mechanical thrust- reverser actuation, re gardless of engine type. Within a week of that, it had revised that direc tive, limiting it to air craft fitted with the PW4000. Now, despite the FAA's earlier re-assur ances (for which it was roundly and rightly con demned by the National Transportation Safety Board), it has instigated a fundamental review of thrust-reverser design for high-bypass turbo- fans, and ordered urgent inspections of the reverser mechanisms of P&W-powered 757s. The review of the philosophy comes after Boeing's windtunnel tests demonstrated that the deployment of a reverser at high speed suffi ciently disrupted airflow over the wing of a 767 as to destroy lift and render the aircraft uncon trollable. This is the first time such tests have been carried out, accepted certification tests in the past having assumed unplanned deployment only at low speeds and less than full power. While that is a worrying finding, it is reassur ing, in that it greatly assists the investigation into the Lauda crash, and provides a firm pointer towards further research into an unsus- It is to he hoped the FAA has acted in time to ensure that there are no more catastrophic incidents." pected (or at least uninvestigated) phenomenon. Even more worrying than the possibility that a similar accident could have befallen any of many aircraft in the past, however, is the acknowledgement, implicit in the FAA's latest statement, that at least some of the accepted reverser-design assumptions and criteria are now invalid. The FAA now says: "It is possible that modern high-bypass engines combined with more efficient thrust reversers have resulted in aircraft which require a new thrust-reverser certification philosophy." The deployment of a reverser in flight, far from being the manageable event which current philosophy has assumed, could now be classified as being "...similar in magnitude to certain pri mary flight-control fail ures..." If that is the case, then this is something which is not confined to Boeing or Pratt & Whitney. It is something which sud denly affects every big twin (and perhaps even four-engined types) and which also affects thrust- reverser design and certification across the range of engines which use reversers. The review will not just be time-consuming (the FAA says it will take a year or more), but it will almost certainly lead to expensive redesign and more-expensive retrofitting of new sys tems. No responsible op erator or manufacturer will quibble at the need to incorporate whatever changes are eventually deemed necessary, no matter how regrettable the cost of implementa tion, In the long term, the industry may look back on this sequence of events as having as profound an impact on airliner design as did the Comet structural failures, or the deep stalls suffered by early T-tailed airliners. Just as importantly, it provides a salutary lesson to those who oversee the aerospace industry^, standards of design and certification. No matter how well a standard or a philosophy has worked in the past, it is only as good as the circumstances which contrived to allow it to be successful, and it must never be assumed that yesterday's assumptions are valid today. That is a lesson which it is never too late to learn. D FLIGHT INTERNATIONAL 18 - 24 September, 1991 3
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