Boeing Rules Out 787 Window Change

Jan 9, 2009
Guy Norris/Orlando, Fla. guy_norris@aviationweek.com

Boeing plans to complete firm design configuration of the stretched 787-9 version in the second half of 2009, but to save weight, it will not be restoring window positions lost as a result of fuselage join issues.

The passenger windows on the initial production 787-8 aircraft are missing a window on each side at locations fore and aft where the pre-assembled fuselage Sections 46/47 and 41/43 are mated. Although designed with a continuous window line, the mating area between the sections required strengthening when attached, forcing Boeing to omit the window along the join line.

Re-design studies showed that strengthening the fuselage join area to re-insert windows was "very complex" and would cost "hundred of pounds" in additional weight, says Tom Cogan, the former 787 chief project engineer, who became director of airplane product development in July 2008.

The loss of a window in the forward Section 41/43 join is not considered a major setback as this is close to the 'door two' galley and lavatory block which does not need one.

The missing window further aft by the Section 46/47 join is a more serious issue, as this section of the cabin is for seating only. However, Cogan says at least one seat row on existing Boeing products is currently blanked off because of air conditioning ducts running up the inside of the fuselage, and that airlines have always adapted to this.

Ironically, Boeing made special efforts to widen the windows on the 787 cabin by taking advantage of the fuselage structure's composite material to route internal systems through narrower spaces between windows than would have been possible on a conventionally built airframe.

Cogan, who was speaking at the New Horizons forum organized to coincide with the AIAA aerospace sciences meeting in Orlando, Fla, this week, acknowledged that the program continues to face "big challenges, but by and large it is looking very positive."

Cogan had been on the 787 and preceding Sonic Cruiser since 2001, describes his appointment away from the troubled program as "a bitter sweet change," but adds the change allows him to take stock of the progress made-to-date.

"It is going well for the most part but obviously we are not where we wanted to be on the schedule. The things we were most worried about, like being the first large aircraft to be made out of composite, and whether we knew how to do it, or if we could make it work, turned out not to be the real issue. As it turns out it, it is the small things like fasteners that keep an aircraft from flying. It is something we tried to pay attention to and one of the things that caused us to be late. But our customers are hanging with us because they know this is a good aircraft they need. They're being patient and it will fly."

Cogan adds the broad target remains of mid-2009, though internal Boeing schedules point to a first flight target of late April.

Cogan also acknowledges the baseline aircraft "is a bit heavier than what we thought. We set a very aggressive target and we learned things along the way such as having electro-magnetic interference protection and designing for that and other changes we added a bit more weight. This does detract a little bit from performance but we still think it will be around 20% more efficient than anything today."

Being more specific, however, Cogan clarifies this adding "compared to the 767 it's not quite 20%, but in that order. Analytically we're doing quite well, but we just don't know how well until we fly. All the indications are today that we'll get it."

As for lessons learned, Cogan fell short of the criticism of the program partnerships meted out by former 787 vice president, Mike Bair, following his 2006 departure from the effort. He did, however, acknowledge the need for some change.

"As for the model we used on international collaboration we'd absolutely do it again, though there are some details we'd probably fine tune a little bit - this was a first on this scale. We'd also worked with a lot of these partners on the 777, though in hindsight we'd change a few things, but just fine tune it. What's important for us is to draw on that intellectual property - we think we have the best technology available."

AviationWeek.com photo by Jennifer Michels

AVIATION WEEK Copyright 2008, The McGraw-Hill Companies, Inc. All Rights Reserved.

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