Business & GA, Commercial, Embedded Avionics

Product Focus: Lighting

By By Ed McKenna | April 1, 2012
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In December Boeing delivered a 737 Boeing Sky Interior to Norwegian Air Shuttle ASA, the airline’s 18th 737-800 with the interior. The system includes the B/E Aerospace LED cabin lighting system, featuring adjustable lighting with full spectrum color capability, according to the company. Photo courtesy Boeing

Light emitting diode (LED) technology is providing a very visible divide between newer and older generation aircraft. For manufacturers and operators of the new platforms, such as the Boeing 787 and Airbus A380, the plush, LED lit cabins provide an opportunity to promote their services, while the technology itself is delivering efficiencies needed to address rising operating costs. As the technology continues to improve and carriers take delivery of LED lit aircraft including Next-Generation 737s with the Boeing Sky Interior, operators are looking at upgrading their existing fleets with LED lighting. However, as they build the business case for retrofit programs, those operators must take into account some formidable technology and cost issues.

Moving forward, “all new aircraft will be LED,” said Beth de Young, vice president and general manager at IDD Aerospace. The technology provides not only weight and power benefits but also gives operators greater control of their lighting, she said. Furthermore, “the price (of LEDs) is now equivalent or better than previous technologies, such as incandescent or fluorescent (lighting).” Redmond, Wash.-based IDD, which provides lighting technology primarily for the flight deck, has “thousands of LED part numbers right now … (and) are well on the LED path,” de Young said.

While it’s on virtually every new transport and business aircraft, the aftermarket “is lagging a little bit … (but) the interest is growing,” said Stephen Scover, vice president and general manager, lighting systems at B/E Aerospace, which provides the LED lighting systems for the Boeing Sky Interior (BSI). “As the newer aircraft come out with the ability to alter color in the cabin, the retrofit market (will) follow.”

The momentum for LEDs in both the forward and retrofit markets has been built on steady technology improvements. “On a lumins per watt basis, over 10 years it has doubled the output, so now we are looking at 140 to 150 lumins per watt where 10 years ago it was tough to get to 85 or 95,” said de Young. Those latter chips represented “the top of the market then … (and cost) $25 a package, and now they are down to (about) $3.50,” said Doug Daman, IDD’s senior electrical engineer. 

Goodrich manufactures a range of interior cabin lighting products, above, for commercial and business aviation. The company is in final qualification testing for an exterior, LED wing strobe light, and is developing a sidewall and ceiling cabin light.  Photo courtesy Goodrich

This boost in energy efficiency helps OEMs and operators conserve energy needed to power “more and more technology devices for passenger comfort” that are being put on aircraft, said Rolf Brölemann, segment leader business and regional jets, Lighting Systems, Goodrich Interiors in Lippstadt, Germany. “LED technology can offer an overall 50 to 75 percent power saving for an aircraft lighting system.”

For airlines looking at a retrofit, the boost in energy efficiency may be important, but a “primary cost… (driver) is how often (they) have to replace the lights from a servicing perspective,” said de Young. By this measure, LEDs easily outperform older technology. At about 500,000 hours, the useful life of an LED is about five times that of an incandescent light, according to IDD Aerospace. The meantime between failure is pegged at more than 300,000 for the LEDs compared to 23,000 hours for incandescent bulbs.

“Performance also includes the light quality,” said Brölemann. “The quality in terms of available color temperatures and LEDs with high Color Rendering Index is the area where we have seen the most improvement right now and expect (to see) even more in the near future,” he said. “LED temperature resistance has (also) increased. … Ten years ago, LEDs had a maximum junction temperature (maximum allowed temperature of the LED chip) of Tj (terajoules) of 100C, today LEDs are available with Tj of up to 140 degrees C,” said Brölemann.

The advancement in LED technology is also spreading outside the aircraft as well to landing and taxi lights, said Scott Sweet, interior lighting product manager at Emteq, based in New Berlin, Wis. This expansion in capability has been achieved thanks to “the natural evolution and advancement of LED technology” combined with smart optical design and power and thermal management, he said.

Also, offering a wide breadth of aircraft lighting products, Goodrich is preparing to rollout a new exterior wing strobe light that Brölemann says combines “a high illumination level … (and) extremely sharp flash pattern” that is unlike any previous LED strobe light. The product is in final qualification testing. “The visual performance is at least as good as a xenon flash tube strobe light,” he said. Goodrich is also set to introduce “a high class sidewall and ceiling light” for general cabin lighting in single and twin aisle aircraft that provides “cabin illumination levels that are twice as bright that fluorescent tube cabins,” Brölemann said. 

Overall, the major focus of the LED upgrades has been largely on the cabins, with airlines looking to improve the passenger experience.

This photograph illustrates the evolution of LED technology in packaging over the past 10 to 15 years. Unlike the relatively mature incandescent market, solid state LED packaging properties are being driven by a variety of consumer applications. Photo courtesy IDD Aerosapce

“It is a matter of the business case,” said de Young. “The technology is available (for the flight deck), and we have lots of LED solutions on incandescent aircraft, but a whole LED retrofit of a cockpit (is unlikely) unless you are addressing a specific case like NVIS (night vision imaging systems) upgrade.” She added that LEDs have matured to the point where a company can develop the solutions for the cabin but it still complicated and expensive to replace wiring on the flight deck. IDD is working on “a few things with embedded circuits” that could make it unnecessary to replace the wiring, she said. “But if you (have to) touch the wiring on an aircraft the price goes through the roof.”

Boeing Sky Interior

Along with technology advances, the interest in LEDs is being piqued not only by the rollout of the A380s and 787s, but also a growing number of new Next-Generation 737s being delivered with Boeing Sky Interior. Between late 2010 and the end of 2011, Boeing delivered 200 737NGs with the BSI, a redesigned passenger cabin based on the 787 interior. Currently being offered as an option on NGs, Boeing has said it expected about 85 percent of its backlog of more than 2,300 of those aircraft to be delivered with the Boeing Sky Interior. In addition, BSI will be standard on the 737 MAX when it is introduced in 2017.

“The overall acceptance of the Boeing Sky Interior … has been a major event in the market,” said Scover. “I look at BSI as a turning point; I think it has brought a lot of people to the realization that lighting within a cabin environment can make a difference to the passenger experience.”

The introduction of BSI “has definitely created market interest” among “several customers who have taken delivery of those aircraft and want a similar effect with the rest of their aircraft,” said Matt Davis, program manager and air transport lighting product manager at Emteq. It has also gotten the attention of industry. At Emteq, “we need to be able to come up with a solution … for the retrofit market to compete with that new type of interior.”

In the near term, a key driver of that retrofit business is expected to fleet continuity. Carriers that are taking delivery of new aircraft have to decide whether “they want to maintain a mixed fleet or … (create) a specific look in their interiors, which I think is opening up a door to a retrofit market in a much broader fashion,” Scover said.

Scover said B/E offers a “very scalable” approach to retrofit. It can be done in the entire cabin or in a tiered method beginning with “premium priced cabins” that includes “the hooks and handles” that will allow the company to do the remainder of the cabin, he said.

LED Challenges

While offering advantages, LEDs also present challenges to operators of even new aircraft. An overriding concern involves managing the rapid rate of LED technology change that is being driven by the automobile and consumer electronics markets.

“Within those … markets, there is kind of a philosophy that brighter is better, which is driving components to be replaced or updated with the next brightest bin component” at a rapid rate, said Kevan Guy, engineering manager optical and mechanical engineering at IDD Aerospace. This kind of change rate creates obsolescence and technology management issues that clash with aerospace’s primary requirement for “a consistent product over longer time horizons” of up to 20 years, said de Young.

Compared to the OEMs, operators are contending with structural issues in existing aircraft that are making the return on investment from retrofit difficult to achieve within a reasonable time, said Brölemann. For example, “older aircraft interfaces … are not optimized for the use of LEDs, (so) the LED products have to compensate (for) these disadvantages … (by) reducing the optimal benefit to the aircraft operator,” he said, adding the bigger the modification package the more efficient the LED implementation is.

In the cabin, “the primary challenge for lighting design is to get the product performing properly with the limitations of where bin structures and ceiling structures and side walls are,” said Scover. To address this challenge, which Scover characterizes as more optical than electrical, B/E has developed “simulation techniques and software that can give customers a relatively good idea of how that cabin is going to look (with the new lighting) prior to us installing lights,” he said.

Along with the complications, there are considerable costs associated with the retrofits. “The lower power consumption is a very attractive feature for new forward fit aircraft; however, for aircraft that are equipped with incandescent or fluorescent tube lighting it can be expensive to replace the aircraft wiring that controls the lighting,” said de Young. The cost can be attributed not just to the equipment and labor but the fundamental differences between older lighting systems and LED.

However, due to media presentations and the required reductions in the emission of CO2, especially in Europe, “airlines are more convinced about the need to implement LED technology than before,” said Brölemann. “The initial investment is not cheap, due to the requirement to change multiple parts of systems … (and) the return on investment is usually longer that 18 month depending how much value the airlines place on the aircraft downtime,” he said. “The continuous replacement of bulbs is annoying but the cash outlay is fairly low,” he said. Due to that not all airlines are working … on retrofit solutions with LED lighting Systems.”

Even as the industry tackles the challenges still posed by LEDs, it continues to explore the validity of newer and very thin Organic LEDs (OLED) technologies. “Organic LEDs are of significant interest to anyone in the lighting industry, but in terms of general illumination they are still a few years away, and looking at technology roadmaps I think what you see is a competitive improvement in what I would consider generic LEDS for a period of time before OLEDs can really catch up,” said Scover.

Other lighting technologies being explored include remote phosphor lights which involve the separation of “white LEDs into a blue light source and a solid Phosphor piece, plate or fiber,” said Brölemann. These products are entering the market right now which should allow for the improvement of the homogeneity of different applications, he said. The technology could be use in domes and general light applications on aircraft.

Next month: Synthetic Vision Systems

Avionics Magazine’s Product Focus is a monthly feature that examines some of the latest trends in different market segments of the avionics industry. It does not represent a comprehensive survey of all companies and products in these markets. Avionics Product Focus Editor Ed McKenna can be contacted at [email protected].

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