Guy Norris/CINCINNATI
Airbus Industrie and CFM International (CFMI) are in talks on proposed development of an upgraded A340-200/300 with an engine variant combining the CFM56-5C with the core of the CFM56-5B/P. At the same time, the General Electric/Snecma venture is adopting automotive assembly techniques to improve production efficiency.
No firm agreement has yet been reached on a possible A340 development, says CFMI, which wants to include the upgrade with other aerodynamic and system improvements to provide a more significant performance boost. CFMI says the plan, if sanctioned, could breathe new life into the baseline A340 family. It is concerned about the shifting focus to the Rolls-Royce Trent 500-powered A340-500/600 variants in development.
"There is a need to improve the exhaust gas turbine margin on that engine," says CFMI president Gérard Laviec. He adds that the upgrade would primarily exploit the three-dimensional (3-D) aerodynamic design developed for the high pressure (HP) compressor of the -5B/P. The engine was developed in the mid-1990s as the -5BX and provided the basis for the improved -5B/P powering the Airbus A320 family, as well as the CFM56-7B on the Boeing Next Generation 737.
CFMI's plan calls for the improved 3-D HP compressor, HP turbine and possibly modified low pressure (LP) turbine of the -5B/P to be mated to the 1.82m (72in) fan and LP system of the -5C.
Laviec says the move would increase the operating margin, improve payload in hot-and-high take-off conditions, give longer life on wing and cut maintenance costs. The plan is aimed at new A340s, but retrofits are an option. The A340-200/300 family is powered by the 31,500-34,000lb-thrust (140-151kN) CFM56-5C family.
While it looks at options to upgrade the basic A340, the company is investigating methods to dramatically improve its own efficiency, experimenting with a moving final assembly line. The aim is to slash cycle times by 50% and achieve record levels of sustained productivity, with about 1,050 engines due for delivery this year.
The manufacturing process is based on an automobile final assembly concept adopted on Boeing's 717-200 production line at Long Beach, California. The system is initially being tried on the CFM56-7 for the 737NG, which, with 555 deliveries due this year, represents more than half the company's output for 2000.
For the experiment, only the engine's fan assembly is moved down the line, as opposed to the traditional build-up method at a fixed assembly station. If successful, the whole engine, including the HP core and LP turbine module, will move to the process. The concept borrows from techniques developed by Toyota, and will be extended to include the -5 and -7.
"Our volume is so high, we thought we would try it out on one engine to start with," says CFMI production manager Ken Foley, who adds that overall cycle time reductions being achieved are "doing wonderful things to our cost flow". The production line in Evendale, Ohio, now produces four CFM56 cores a day. It is also shipping two complete engines to Boeing every day for the 737 line. The current 737 production rate requires the supply of up to 53 CFM56 engines a month.
Based partially on the new processes, CFMI plans by June to cut overall assembly cycle time to seven working days. Cycle time, which covers the period from the start of component build-up to shipment of a completed powerplant, stood at between 18 and 19 working days in the mid-1990s and was whittled down to around 11-12 days last year, says Foley.
Source: Flight International
