Boeing studies new “sweet spot” for 787 windows

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A key Boeing supplier says the airframer is considering spreading the electrochromic dimmable windows technology introduced on the 787 to other airliner types.

Boeing, meanwhile, is studying whether it should increase or decrease the level of opacity offered by the dimmable windows after gathering more than a year of feedback from passengers flying on board 787s.

While the Chicago-based airframer remains silent on new applications for dimmable windows, electrochromic supplier Gentex says that its customer is indeed considering new applications.

"Boeing has also expressed interest in utilising dimmable windows with other aircraft," Mark Newton, Gentex senior vice president and director, said in a conference call on 23 October.

The electrochromic technology supplied by Gentex is integrated into PPG Aerospace's interactive window systems on both the 787 and the Hawker Beechcraft King Air 350i. Each 787-8 requires about 100 dimmable windows, Newton says.

The new windows eliminate the need for pull-down window shades except in the lavatories for some airline cabins. They give passengers some control over the amount of visible light allowed into the cabin, but flight attendants have the power to control all of the windows simultaneously.

The Gentex electrochromic technology passes an electric current through the conductive coatings of the inner- and outer-transparent plies, creating a chemical reaction that changes the opacity of the surface.

It is not clear which Boeing aircraft is being considered, but the airframer is in the process of deciding the technologies that will be offered with the 777X. This re-engined and possibly re-winged version of the 777 airframe is expected to heavily leverage technology developed for the 787.

"I think the broad answer is that this company has absorbed a lot of development risk over the last decade but now that we're coming out of it, we have a suite of technologies that we can harvest in a de-risked environment for the next decade or two," Boeing chairman and chief executive James McNerney said in an earnings conference call today.

For passengers, dimmable windows are among the most visible new technologies introduced on the all-composite 787 airframe, and one of the most frequent targets for comments both positive and negative. Several media reports surfaced in June about complaints from All Nippon Airways that the dimmable windows are not dark enough, although the airline later denied making any such complaint to Boeing.

But Mike Sinnett, Boeing's 787 chief project engineer, says the 787 cabin windows are the focus of an ongoing study that could lead to tweaking the opacity levels.

"There are going to be some customers who would prefer it were lighter and there are going to be some customers who prefer it would be darker," he says. "I think we all have to gain some fleet experience together to a) decide whether or not we really hit the sweet spot, and b) decide what we might want to next, if anything at all."

Boeing's goal was never to allow the windows to become fully opaque, but to reduce by orders of magnitude the amount of solar radiation entering the cabin, he says.

"In general, I'd say we did a really good job of hitting the sweet spot," he says.