GUY NORRIS / LOS ANGELES
Simulated altitude tests for troubled Airbus A318 engine include alternative MTU design
Pratt & Whitney has set a 15 May deadline for making the final choice of high-pressure compressor (HPC) design for its troubled PW6000 turbofan for the Airbus A318. It has begun simulated altitude tests of a complete engine with one of the alternatives, the MTU design, in the run-up to the decision.
The baseline engine programme has been delayed 30 months to correct excessive fuel consumption, which is around 6% higher than predicted. Entry into service is set for mid-2005 against the original target of November 2002. P&W says the added time translates into a "36-month window" in which to complete development with either a revised seven-stage P&W-designed alternative HPC or a six-stage MTU design first rejected by the US manufacturer in August 2000.
Although the competing CFM International CFM56-5B is now the lead engine on the A318, Airbus is anxious to stabilise the orderbook for the P&W-powered variant. Several customers, led by International Lease Finance and Frontier Airlines, have already swapped from the PW6000 to the CFM56 as the performance issues have emerged. Airbus is believed to be pressing P&W to make a "once and for all" HPC decision.
The MTU HDV12 compressor design started running in a PW6000 at P&W's Wilgoos, Connecticut site earlier this month and "looks very promising" in altitude chamber tests, says P&W. The compressor was designed from the outset as a drop-in replacement for the original PW6000 HPC now flying on the A318 prototype. Described two years ago by P&W as a "back-up", the MTU compressor is based on technology derived from the German government-funded Engine 3E research programme.
Should the MTU unit be selected, as is now widely expected, the German company is likely to negotiate up to a 20% risk and revenue sharing partnership in the PW6000 programme. MTU is now a "preferred life-time supplier" to the engine effort and provides the low-pressure turbine.
P&W officially rejected the MTU design because it had "more data on the five-stage design" and the established compressor was believed to be "the best approach to certification".
The low-parts count design of the original HPC - fewer than 2,000 blades and vanes compared to more than 3,000 in its competitor - was also key to P&W's low operating cost goals for the engine.
Source: Flight International
