Passenger and aircrew well-being is moving up the agenda for airlines, which are seeking new ways to combat old enemies such as air quality and legroom
Growing concerns among aircrew and passengers about the aircraft cabin environment have prompted ongoing efforts to enhance the quality of everything from cabin air to potable water, along with reducing noise and vibration, and improving lighting and waste-disposal systems. Many advances being introduced into airline cabins have found their first application in the more comfort-conscious and less cost-sensitive executive jet sector.
Cabin air quality is being addressed by the Donaldson Company with the introduction of a new anti-microbial, high-efficiency particulate air (HEPA) filter. The Minneapolis, Minnesota-based firm's BioAdvantage HEPA cabin-air recirculation filter was delivered to launch customer Southwest Airlines in September last year for installation on the carrier's Boeing 737 fleet.
BioAdvantage combines HEPA filtration with an anti-microbial additive developed by Huntersville, North Carolina-based Microban Products. The Microban additive has had numerous applications, including toys, shower curtains and hand soaps, and is effective against a broad spectrum of bacteria, fungi, yeast and certain classes of viruses that can cause filter degradation.
Recirculation
The HEPA filters are approved replacements for conventional cabin-air recirculation filters for all Boeing and McDonnell Douglas types, and the Airbus A320 family.
According to engineering manager Dan Adamek, Donaldson is developing a new line of cabin-air recirculation filters designed to capture and eliminate odours from airborne molecular contaminates, gas phase contaminates and volatile organic compounds. "Although it has not been proven that odours from these sources present a safety hazard, we want to offer a product that will be in front of any conclusions the research should make. Compared with current filters, they will offer a lighter, improved performance alternative," he says.
But air quality also depends on humidity levels, as extremely dry cabin air at high altitudes has been implicated in the spread of viruses, and drying of the eyes and skin, as well as jet lag. The problem may be significantly alleviated by a humidifier developed by CTT Systems of Nykoping, Sweden. Originally marketed to upper-end corporate and head-of-state aircraft operators, the Zonal Comfort system has just completed 6,000h testing aboard an Scandinavian Airlines Boeing 767-300 - its first application to a commercial airliner in revenue service.
Ulf Liljenberg, vice-president sales and marketing, says the Zonal Comfort system is being targeted at first- and business-class cabins on widebodied aircraft, where the ambient air humidity is typically 5-7% percent. The system can provide a relative humidity level to between 20-25% with humidifiers that use the aircraft's potable water supply to moisten the air going through the cabin-air recirculation system. The humidified air in the forward cabin ultimately benefits passengers in the more crowded economy section, where humidity is naturally higher. Liljenberg says the Zonal Comfort system is designed to work in tandem with CTT's Zonal Drying system, which prevents moisture build-up in the aircraft's crown insulation blanket.
CTT expects to certificate the Zonal Comfort system on the Airbus A330/A340 by year-end, with SAS the likely launch commercial carrier. For the A330/A340, Liljenbert says, the system will include five humidifiers installed in the aircraft belly, using 28V DC power. The system will weigh 120kg (265lb), with an hourly water consumption of 22 litres (5.8USgal).
"A strong interest in the system has also been shown by Boeing for use on the 7E7, and by Airbus for the upper deck of the A380, either as an option or standard equipment," Liljenberg says, adding: "Airbus has selected Zonal Comfort as an option for the cockpit and cabin-crew rest area of the A380."
Along with better air quality, the airlines are equally concerned about potable water, especially as sanitation standards differ worldwide. To assure a clean supply of onboard, non-bottled drinking water, International Water-Guard Industries of Burnaby, British Columbia is marketing its circulating potable water system (C-PWS) to airlines, after six years of success in the executive and head-of-state aircraft sectors.
The C-PWS represents a significant advancement over other onboard water systems in several respects, says Bill Coote, president and chief executive. "C-PWS is the first aircraft potable water system to employ pump-driven constant circulation instead of the high-pressure engine bleed air that drives conventional onboard water systems," he says. "The result is elimination of freezing, since the water is constantly circulating. That also dispenses with the need for heater ribbons used on potable water distribution lines used on most aircraft today. These heater ribbons have been implicated in in-flight fires and remain a safety concern."
Bacteria killed
The C-PWS uses a carbon-block depth filter in conjunction with an ultraviolet light chamber that kills water-borne bacteria. The filters, Coote says, are constantly improving the quality of water as it circulates so there is almost no opportunity for bacteria to grow. Because water circulation is not driven by pressurisation, the tanks can be custom designed to conform to fit the exact area of installation in the aircraft. This results in lighter tanks that use less space.
"On a Boeing Business Jet, the conformal tanks can accommodate 120USgal of water in the same amount of space that is required for a conventional 60USgal system. Depending on the aircraft, weight savings range between 30% and 60%," says Coote. With fewer moving parts, C-PWS is proving to be more reliable than bleed-air driven systems, he says. "To date, the C-PWS has shown a mean time between failure rate of over 100,000h."
International Water-Guard received initial supplemental type certification for C-PWS on the Bombardier Global Express in late 2001. Certification on the Boeing Business Jet and 737-700 are scheduled for May. A supplemental type certificate (STC) for the Gulfstream G400 is expected to be approved in July. A real-time water quality monitoring component is scheduled to be added to the C-PWS by 2006.
Along with air and water quality concerns, cabin crews have long complained about excessive clogging of galley drainage systems, especially in the premium-class sections of widebodied aircraft flying long-haul international flights which feature multiple meal service.
Waste disposal
Monogram Systems, a division of the France's Zodiac Groupe, believes it has come up with a solution to this problem, according to Ken Khteian, the Carson, California-based firm's director of airline sales. The galley waste disposal unit (GWAD) was originally developed for Cathay Pacific Airways' Boeing 777s. "Cathay Pacific realised that food and liquid waste don't compact very well in a trash compactor, so the cabin crew would try to dispose of the waste down the galley drains," says Khteian. "The problem was that traditional galley sinks are fitted with a 0.5in [12.7mm]-wide drain line designed to accommodate potable water, but not solid waste, especially when combined with liquids such as wine or milk. That resulted in clogged drains and corrosion, mandating costly maintenance and repair."
Efficient evacuation
GWAD uses a 51mm-wide drain line and Monogram's vacuum lavatory waste disposal system technology, used throughout the airline industry. As Khteian points out, the vacuum system more efficiently evacuates the food and liquid waste from the galley sink to the existing lavatory waste tank located below the aircraft cabin floor.
Since Cathay Pacific became the launch customer, the GWAD has been installed on Qantas Boeing 747-400s. The Australian carrier has also ordered the system for its A330s and A340s, which will be delivered this year. GWAD has also been specified as the baseline equipment on the A380. "Our customers say they have seen a significant reduction in drain clogs, and the associated maintenance costs," says Khteian.
Another market for GWAD is the top-end business jet. "Several have been installed on Boeing Business Jets; but, as the reputation of the system grows, we believe it will be specified on most commercial widebody, long range aircraft."
Airline passengers have long been subjected to cabin noise and vibration levels that interfere with normal conversation and contribute to jet lag. While electronic noise canceling systems have been deployed on some aircraft, a relatively new approach has been taken by Flight Environments. The Paso Robles, California-based company specialises in aircraft-specific noise and vibration attenuation solutions, using thermal and acoustic insulation technology. The customised solutions, according to company president Eamon Halpin, draw from more than 80 different insulating materials made of fibreglass reinforced plastic, polymers, ceramics and felts. The lightweight materials require minimal maintenance and meet new regulations governing flame propagation and burn-through, which will be implemented in 2005 for aircraft with more than 19 seats.
"We use four criteria for the noise-treatment materials selected," Halpin says. "They must be lightweight, fireproof, easy to install, and have little to no moisture retention." Before the material is chosen, Flight Environments performs a complete noise and vibration survey of the aircraft, through a series of ground and flight tests involving the aircraft's complete flight profile. "By establishing a noise signature for the aircraft, we can determine the source of the noise and the direction it is coming from. Based on that, and using the manufacturer's design, we can select the right material and components to produce a tailor-made solution," says Halpin.
More than 550 custom installations have been completed worldwide over the last four to five years on a wide range of aircraft. The company holds 30 STCs, mostly for installations on corporate and head-of-state aircraft including 22 Boeing Business Jets. More recently, the company has obtained STCs on the Bell 407, Bell 430 and Sikorsky S-76 helicopters. But Halpin believes that future uses will increasingly include commercial airliners.
Insulation
"The new FAA [US Federal Aviation Administration] ruling on aircraft insulation, coupled with the realisation that they can provide commercial airline passengers with the same level of comfort as on corporate aircraft, has airframe manufacturers taking a fresh look at this whole area," he says. "We expect to see an increasing percentage of our revenue coming from this sector."
Cabin environment is also connected to ambient lighting, and light emitting diode (LED) technology holds much promise for airline operators now that it has proven successful in corporate aviation.
Heads Up Technologies of Carrollton, Texas has partnered with the Osram Sylvania subsidiary of Germany's Osram to offer LED systems that are being installed, starting this year, as baseline equipment on the Cessna Citation X, Excel and Sovereign business jets. The company also holds an STC for LED lighting installations on the Citation Model 650 family.
In addition to ease of installation, design flexibility, greater reliability and durability, as well as weight savings, LED lighting offers several cabin quality advantages, according to David Groos, the company's senior vice-president, sales and marketing. "LED provides a wide range of colours, which is very important to interior designers, who are trying to set the right mood," Groos says. "Along with this, there is a tremendous variation of intensity between zero and 100%. Passengers, especially on corporate jets, appreciate the ability to select the right lighting intensity."
Heads Up Technologies sees a definite application of LED lighting technology to commercial airliners. "We have been able to show that LED technology has great potential for the commercial market, based on our experience with corporate jets," Groos says. It likely that other cabin comfort enhancements not being implemented in business jets, such as "silent" air conditioning and distribution systems, will find their way into the far more pedestrian cabins of commercial airliners.
Boeing's 7E7 is at the forefront of new cabin-design concepts
Airbus cabin concepts for the A380 promise greater comfort – for some travellers
Executive jet-style comforts are finding their way into airliner cabin concepts
Advances in waste disposal units could reduce clogging
PAUL SEIDENMAN / SAN FRANCISCO
Source: Flight International