A 32m (105ft) mandrel sat empty in Boeing’s composite wing centre during a media tour on 1 June in early June. But within days of the visit Boeing expected to activate a new kind of robot that can place carbonfibre tape in 82cm-wide swaths, forming the first composite piece of the first production version of the 777-9.
On paper, Boeing still has up to three years to deliver the first member of the re-engined, re-winged and heavily updated 777X family. That may seem like plenty of time for an aircraft type that Boeing originally flew 23 years ago, but the challenges facing the 777-9 go well beyond proving its lofty fuel efficiency targets.
In the process of introducing the 777-9, Boeing is re-inventing the final assembly process for a widebody airliner. Instead of building a large aircraft amid towers of scaffolding in a process not unlike erecting a skyscraper, Boeing will build 777s much like General Motors assembles cars. The large tooling towers and scaffolded jigs will disappear. Fuselage panels will move through the assembly line on cradles driven by automated guide vehicles, fitting together like the world’s largest Lego pieces.
Boeing must accomplish that transition during a dynamic period. The production rate for the 777 is declining from seven per month today to five per month in August. Meanwhile, Boeing must master several new technologies as it prepares the 777-9 to enter service in 2020, with folding wingtips, touchscreen displays and a set of narrower frames stretching all the way down the fuselage.
The scale of the challenge is acknowledged among the executives managing Boeing’s 25-year-old 777 final assembly line in Everett, Washington. “This is a breakthrough set of transformations that we’re going through. We’re going from technology that we know very well and traditional tooling methods to more software-based approaches with automation,” says Jason Clark, Boeing vice-president for 777/777X operations.
Boeing’s track record with transforming production processes is mixed. The company has kept the 737 Max on track even as it as increased the monthly production rate for all 737s by about 25% since the programme was launched. But the last widebody Boeing introduced – the 787 – experienced severe delays with the production system during and after the development phase.
The goal is for the 777X to emulate the narrowbody 737 Max, but at the scale of a widebody programme like the 787. The latter suffered not only production breakdowns, but also a series of reliability flaws that took several years to resolve in service. The 777X integrates several cockpit technologies introduced by the 787 with existing systems from the 777-300ER. Boeing’s goal is to introduce the 777-9 at a much higher level of reliability than it achieved with the 787-8 in 2011.
Boeing executives think they found the answer to the reliability problem with the 737 Max programme. The first 737 Max 8 entered flight test with production-ready hardware, rather than developmental systems.
Traditional final assembly methods that serve the 777 programme are to be replaced by techniques familiar in the automotive industry
Boeing
“Some of you saw what happened to the 787 when it originally went into service and it had some reliability issues and if we enter the flight test programme with production-level software and system hardware in the airplane then we can fly the airplane similarly to the way our customers fly the airplane,” says Eric Lindblad, Boeing’s vice-president and general manager for 777/777X. “We took that page out of the playbook of the 737 Max.”
As another re-engining programme, the 737 Max offers other lessons for the 777X programme. With the 737 Max, Boeing faced the challenge of introducing a new model even as it continued producing the older aircraft. Rather than introduce the new model on the existing assembly line, Boeing established a third final assembly line dedicated to the 737 Max flight test aircraft. As the rate of deliveries of the 737 Max rises, the re-engined aircraft will be introduced on the existing lines.
The 777X programme is following the same strategy. During the media tour in early June, a low-rate initial production line for the 777X was being constructed in the Everett bay that previously housed the temporary surge line for the 787.
Within a few months, workers on the final assembly line will start working on a “practice” wing. Although not intended to be used on a static or flying test aircraft, the structure is geometrically a match for the 777-9 wing. It will allow Boeing’s engineers and machinists to learn how to use the new automated drilling, fastening and transportation systems.
“It’s an automotive approach,” Clark says. “Often we make the first realisation on the very first airplane. We’ve learned through that process that that’s not the best way to de-risk a new product.”
The 777X LRIP line is being set up as a match for a planned main assembly line, which will replace the existing 777-300ER and 777 Freighter line as 777X deliveries ramp up. It starts with a service-ready wing station, moves to wing-body join, then final body join and finally a functional test position.
“When we try to put a new model on an existing line it’s like riding a bicycle on to the freeway,” Clark says. ”You’re going to have to pedal really fast to be able to do it.”
Unlike the existing 777 line, the LRIP line will not continuously move. Instead, the aircraft pieces will be delivered to each station by automated guide vehicles.
“All the tooling that you see here are pretty much duplicates of what’s on the main line, just not in a moving configuration because of the space that we have. You have to have space. We don’t have the space in here. It’s just a physical constraint. We have to test all the tooling to make sure movement is allowable. It just won’t be in a moving configuration,” Clark says.
Ahead of the final assembly phase, Boeing is still working to prepare its most ambitious changes planned for the 777X programme. The existing 777 arrives at Everett in up to 15 major sections, including the keel, floors, side panels and crown panels. Each of those pieces is built up into three major sections: forward fuselage, mid-body and aft fuselage. Since the original 777 static test aircraft entered final assembly, each of those pieces has been assembled in large structures known as floor assembly jigs.
Boeing machinists attach the keel, floors and panels first to the jig, then to each other and then to the same components in other sections of the fuselage. The pieces are made with great precision, but not perfection. As they come together in Everett from suppliers in Japan and Wichita, Kansas, some parts have areas that are not quite shaped correctly. The jig allows Boeing to apply shims or other fillers to areas that are not made to the specified tolerance.
“It’s a technology and a methodology that’s been tried and true in the industry for decades,” Clark says. “And what it does is it takes large configuration panels – panels we get from Japan or Wichita or wherever it might be – and you actually use the tool to get it back into configuration, and what it does is, it sucks up all that tolerance that we talk about. You don’t have to have the parts fit together, in other words. What that [jig] does is it creates different adjustments that have to be made throughout the [fuselage] barrel.”
By the 1980s, car manufacturers had moved away from such methods to a determinate assembly process. In this jig-less system, the parts are made to fit precisely together from the beginning.
“When we went to the free-form state where the panels actually fit together, what we found was a marked improvement as you started to build the airplane downline – final body join, wing body join,” Clark says. “You truly understand the tolerancing and the gaps and the barrels fit together better downstream. That was one of the key characteristics that we really wanted to drive through the process.”
“I know this is novel – you design it to fit together, you manage the tolerancing and controls of the processes in the supply chain, you actually get a much better end-product,” he adds.
Source: FlightGlobal.com
