tirsdag 28. januar 2020

Erstatning for B757 langt unna - ATW


Boeing Heads Back To Drawing Board On NMA

 
The revised design for Boeing's new midmarket airplane will build on lessons learned from the 737 MAX.
Credit: Boeing

SEATTLE -- Even as Boeing recommits itself to returning the 737 MAX to service by the middle of 2020, the company says it is going back to the drawing board over plans to develop a new midmarket airplane (NMA).
Boeing plans instead to refocus on a fresh next-generation design that meets the more immediate demands of the market. The revised design will also build on lessons learned from the MAX and potentially incorporate fundamental changes to the company’s traditional approach to flight control philosophy and piloting.
Revealing the change in direction, recently installed Boeing CEO Dave Calhoun says, the “NMA project is going to be a new clean sheet of paper.” Since the program began in earnest in 2015, “things have changed a bit.  Not so much MAX related but the competitive playing field's a little different,” he says.
Boeing was on the cusp of seeking board authority to offer the NMA to airlines in March-April 2019 when the plan was derailed by the second 737 MAX accident and subsequent worldwide grounding of the model. Stemming from earlier 757-replacement studies, the baseline NMA family concept was expanded to include a successor to the 767 and by early last year was considered ready for market. The program was focused on two main versions, the 225-seat NMA-6X and 275-seat NMA-7X, with the larger of the pair expected to be developed first. 
The larger NMA, believed to be dubbed internally as the 7K7-7X, was provisionally targeted at entry-into-service in 2025 and was expected to counter the similarly sized Airbus A321XLR. The new Airbus variant was officially approved by the European manufacturer in June 2019 and has recently gained ground in the key U.S. market where both American Airlines and United Airlines have selected the model. The latter carrier plans to take its first A321XLR in 2024 and begin trans-Atlantic services with the longer-range variant in 2025.
The overall rethink on NMA means that Boeing’s product development strategy is therefore more likely to pivot back to studies of a Future Small Airplane (FSA), a new generation family covering the roughly 160-220 seat sector that targets the bulk of the current 737 market. Although Boeing opted to re-engine the 737 and launch the MAX in 2011 in favor of an all-new FSA, the 4,000-plus order backlog for the MAX means production is set to continue well into the decade even if Boeing experiences significant cancellations. 
This is likely to provide additional buffer time for Boeing to develop a 737-replacement family, which senior Boeing sources say would leverage the work already performed over the past four years on the low-cost production system concepts and advanced materials, structures and systems developed for NMA. Much of the sourcing activity for NMA, including engine selection, was well underway earlier in 2019 when the MAX crisis took hold.
Calhoun indicates he has faith in the resilience of the MAX backlog, despite the grounding, and that this will give the company some breathing room for developing a successor. “I am guessing and projecting that the MAX will hold its own (and) that the market split that existed prior to the MCAS (maneuvering characteristics augmentation system – the flight control system software at the heart of the MAX accidents) will restore itself and that will give us a lot of freedom on that next airplane.  But I wouldn't kid you if there were a reason that that share position didn't restore itself.” 
The revised focus on a new aircraft family smaller than NMA will also challenge the engine makers which, up until now, have been designing new powerplants in the 50,000 lb.-thrust range. The General Electric-Safran CFM International joint venture was competing against Pratt & Whitney to be sole source supplier for NMA and the change in direction may enable Rolls-Royce to re-enter the fray. Rolls dropped out of the NMA race in February 2019 citing concerns over its ability to meet Boeing’s original development schedule. All three manufacturers are now expected to begin evaluating new smaller engines. 
Commenting on the potential change in flight control design thinking that would come with the revised design approach, Calhoun says, “I have had discussions with the FAA, we might have to start with the flight control philosophy before we actually get to the airplane.  Because the decision around pilots flying airplanes, that's a very important decision for the regulator and for us to get our head around.” 
In a reference to how the change may see Boeing move closer to the flight control system approach adopted by Airbus, he adds, “we have always favored airplanes that required more pilot flying than maybe our competitor did.  But we're all going to have to get our head around exactly what we want out of that.  So that'll be a process that will go on alongside of the next airplane development.” 
In an Airbus design the flight control system will protect the aircraft from entering prescribed attitudes and speeds by limiting or augmenting the movement of control surfaces, while in a Boeing fly-by-wire design (the 777 and 787) the pilot retains final control authority to override the limits of the flight control system. 

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