FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
2001
2001 - 3215.PDF
HEADLINES AIRCRAFT DEVELOPMENT GUY NORRIS AND PAUL LEWIS / SEATTLE Airbus set to phase in solution to A340-500/600 weight problem Manufacturer says the "get well" programme will include design modifications to the wing structure Airbus says weight reductions and engine improvements will be grad ually phased into initial produc tion A340-500/600 aircraft. This is to ensure that the first aircraft for Singapore Airlines can meet critical transpacific payload-range targets on the key Los Angeles-Singapore route by 2003. The bulk of the changes are in the BAE Systems-designed and built wing which has contributed most to the weight problem, thought to be in the region of 2,200kg (850kg). Although suspected as far back as 1999, the exact scale of the weight issue is now believed to have been verified by recent flight tests of the initial A340-6O0 test air craft. Despite better than expected aerodynamic performance overall, there is the potential for payload/ range shortfall as a result of increased weight and the impact on predicted fuel burn perfor mance from the aircraft's 53,000- 55,0001b-thrust (236-245kN) Rolls- Royce Trent 500 engines. Airbus says the resulting "get well" programme combines BAE design modifications to the wing structure with a R-R planned The scale of the weight issue is believed to have been verified by initial A340-600 flight tests engine enhanced performance (EP) package. The first of these is in ini tial validation tests and is believed to include scheduling changes to the full authority digital engine control, reduced clearances in the intermediate pressure compressor and alterations to increase the tur bine exit temperature. R-R believes the additional margin built into the Trent 500 design by certificat ing at 60,0001b-thrust will reduce the impact of the operating tem perature increase. Weight reductions are expected to be achieved by reducing mater ial used in various stringers and ribs in the wing, as well as by taking out additional mass from some of the larger forgings within the struc ture. This is made possible because of the extra long billets of alu minium being used for the first time on the A340 wing by BAE. The larger pieces allowed the man ufacturer to remove a large wing joint at the 62% semispan, and have already saved around 1,000kg in structural weight. BAE plans to gradually phase in the structural ENGINE DEVELOPMENT PAUL LEWIS / SEATTLE FNR rethinks 747-400X engine plans Rolls-Royce has revised its earlier proposed Trent 680 engine offering forfutlire growth developments of the Boeing 747-400X in favour of a smaller sized powerplant development based on the new Trent 500 rather than the larger Trent 900 under development for the Airbus A380. Boeing is looking for alternative new powerplants or improvements to existing engines for a series of planned increased growth versions of the 747-400 now under study for 2004. The principal driver is the need to meet the more stringent Quota Count 2 noise limit on aircraft departing from London's Heathrow airport due to come into force next year and which will likely set the standard for other air ports internationally. R-R is now focusing attention on offering a Trent 600 rated at around 63,0001b thrust (280kN), which would be based on a uprated development of the Trent 500. The engine would share the same 2.48m (97.5in) fan diameter as the Trent 500, which has been initially developed as 53- 56,000lb-thrust application for the Airbus A340-500/600, but which is already certified to 60,000lb-thrust. The Trent 680 was originally conceived as a 68,000- 72,0001b- thrust family of engines to power the stretch and longer-range 747X and 767-400X derivatives, develop ment of which Boeing shelved earlier this year in favour of the sonic cruiser. The Seattle-based manufacturer has since begun to look at less ambitious improvements to try and sustain the 747-400 by increasing the maximum take off weight up to 431,000kg (950,000lb). As the Trent 680, the engine would have incorporated a 2.6m diameter fan and used technology being developed for the 80,000lb-thrust Trent 900 to power the A380, including swept blades and a contra-rotating high pressure compressor. changes until reaching the opti mum configuration on aircraft No 24 (first A340-500) for SIA which is due for delivery in the second quarter of 2003. It is unclear if the Trent 500 EP will be ready in time for the first scheduled SIA delivery, but the package will be retrofitable. The changes are critical to meeting the airline's requirement to operate year-round on the 16,260km (8,790nm) route between Los Angeles and Singapore while carry ing 200 passengers. The ability to perform the mis sion was vital to winning the key victory over the Boeing 777-200LR, which the US manufacturer is still seeking to overturn. The development is the latest in a series of weight-related issues to impact the A340-500/600 pro gramme. These date back to at least 1999 when Airbus confirmed it was asking member partners to study a 7,000kg take-off weight increase. This, it insisted, was aimed at increasing margin for future growth rather than to compensate for excessive weight. In February last year Airbus conceded the aircraft were slightly overweight, but believed the positive windtun- nel results showed that both mod els would still exceed nominal range targets. www.fliqhtinternational.com FLIGHT INTERNATIONAL 25 SEPTEM BER - 1 OCTOBER 2001 11
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
