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Aviation History
2000
2000 - 1315.PDF
FAA may order Boeing to redesign rudders on 737s GUY NORRIS/LOS ANGELES DESIGN changes to the rud der system of the Boeing 737, plus operational and maintenance procedure changes, may be ordered by the US Federal Aviation Administration in the wake of an Engineering Test and Evaluation Board (ETEB) investi gation into potential failure modes that could have contributed to two 737 crashes in 1991 and 1994. News of the initial recommen dations was leaked after comple tion of the ETEB's draft report, but the committee's full report is not expected to be submitted until June. The ETEB was convened to examine the 737 rudder system. Its work is almost complete, the last phase involving a four-month test flight in a Boeing 737-200 testbed on loan from Purdue University. The FAA says no discoveries were made that require "any imme diate action". It adds, however, that the board's long-term recommen dation is for design changes to address "failures that can result in hardovers". In the short term, the ETEB recommendations are believed to include changes to operations and maintenance that will detect any potential control problems before they happen. The ETEB discovered 30 "Class 1" failure modes and 16 "Class 2" failure modes. Class 1 modes are considered catastrophic failures with little or no chance of recovery, while Class 2 failures are deemed "hazardous" and put a significant burden on the crew. The new fail ure modes include scenarios for jammed rudder controls and con trol problems from ice build up. Boeing, which is independently conducting concept design work on a revised 737 rudder system, says further statistical analysis is required on the ETEB's failure modes to validate the seriousness of the problems. "We are not saying no work needs to be done. We just don't know enough about these findings and how they might apply to aircraft in the real world. We have done some work on what a 'reliably redundant' rudder system might look like. Now we have to see how the ETEB work relates to that," says Boeing. The statistical analysis will determine if the prob ability of a failure is greater than one in 1,000,000,000. Any mode exceeding this will be re-examined. The manufacturer warns that any alterations, particularly to the "Classic", will have to be closely studied before implementation to "make sure there are no unintend ed consequences". It says the intro duction of the newer power control unit and digital yaw damper on the Next Generation 7 3 7, and the sub sequent retrofit of Classics, "will probably get rid of 90% of issues that have been reported, particu larly since a high proportion have been yaw damper related". 3 Romania's Carpatair boosts international links The expansion of the Saab 340 fleet will allow Carpatair to concentrate on international services to Italy ROMANIAN regional airline Carpatair is expanding its fleet with the acquisition of a Saab 340 on lease from Crossair and plans to acquire a second aircraft from the Swiss airline in June. The airline, a sister company to Moldavian Airlines, will use the air craft to build international services from its Timisoara hub, reports Flight hrternationah sister online service Air Transport Intelligence (ATI). Crossair is phasing out its Saab 340s as it takes delivery of new Embraer RJ-145 regional jets. Carpatair, which began services a year ago, already operates anoth er Saab 340 and a Yakovlev Yak-40 under a wet-lease agreement with Moldavian. It is using the newly acquired 33-seater to boost its charter operations with the prima ry focus on international flights to Italy, according to ATI. The Italian cities of Bergamo, Verona, Treviso, Trieste, Bologna and Firenze are served from Timisoara. • MARKETPLACE ++ British Midland (BM) has selected the Rolls-Royce Trent 772B for its new Airbus A330- 200s, in a deal worth $350 million. BM, which has four A330s on firm order and options on eight more, will take two of the aircraft through an operating lease deal with Inter national Lease Finance (ILFC). Deliveries will begin next April. ++ BWIA West Indies Airways has begun seeking buyers for its four Lockheed L-1011 TriStar 500s, with Cabot Aviation appointed to remarket them. Boeing 767-300ERs or Airbus A340s are the leading candidates to replace the ageing, 20-year-old tri-jets. ++ Air New Zealand has ordered an additional ATR 72-500 for its Mount Cook subsidiary. ++ Swissair will boost its Airbus A340-600 fleet with the lease of two examples from ILFC. The air line, which has nine A340-600S on order directly from Airbus, will take the two aircraft from ILFC in February and March 2004 on 10 year leases. ++ Finnair says it will standardise on the A320 for its short-haul fleet, and will expand its acquisition beyond the current 12 firm orders either through the con firmation of its 24 options or oper ating leases. The airline says it is also studying the possibility of a joint purchase with other oneworld alliance partners. ++ Air Sey chelles has concluded a deal with ILFC to acquire a Boeing 737-700 on eight-year lease and swap a leased Boeing 767-200ER for a larger -300ER next year. ++ Ansett New Zealand is acquir ing two used Bombardier Dash 8 Q300s, on lease from the manu facturer. ++ UK leasing specialist Airep has taken delivery of the first of three Tupolev Tu-204- lOOCs. The aircraft is operating proving flights for TNT from its Liege hub. ++ Flight InternationaFs sister on-line news service Air Transport Intelligence reports that Philippine Airlines' (PAL) credi tors are to allow the carrier to re introduce two Airbus A340-300s and retain a further two that were to have been withdrawn from ser vice this month. FLIGHT INTERNATIONAL 25 April - 1 May 2000
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