Cabin environment has been a major element of the completion process in the past couple of years, and it promises to become more so as concerns about air quality and drinking water grow.
There is sufficient concern that the FAA is establishing a Center of Excellence for Airliner Cabin Environment Research at Auburn University. The facility is expected to produce valuable information about air quality as well as protection against chemical and biological threats. The FAA will spend $1 million in the first year and $500,000 a year for the two succeeding years.
Outside the walls of government and the ivy halls of academia, vendors are offering new technology that promises cleaner air and protection against the spread of bacteria and viruses. Englehard of Iselin, N.J., has developed a new system it claims will reduce ozone concentration by more than 90 percent as well as remove a “substantial portion” of volatile organic compounds such as fumes from jet fuel. For business aircraft flying at 51,000 feet, in the lower reaches of the earth’s ozone layer, ozone introduced to the cabin through the bleed-air system may well create a health hazard to crew and passengers. The ability of the system to reduce hydrocarbon concentrations in the cabin air is an added benefit.
Earlier this year, Marshall Aerospace at Cambridge in the UK teamed with Cabin Air Sterilisation to promote an “air sterilization” system designed to reduce the spread of airborne virus and bacteria–including severe acute respiratory syndrome (SARS) and avian flu–throughout the cabin. The technology sterilizes air by exposing it to strong UV-C ultraviolet lamps for less than half a second and can be installed through “a simple modification” of the existing air recirculation systems, HEPA filter and fan units.
Swiss-based Askair Technologies is developing another cabin air sterilization system. The two-stage device (convergent vortex and divergent vortex) is mounted in the existing cabin ductwork and destroys viruses and bacteria by subjecting them to alternating positive and negative plasma zones. In the self-sustaining plasma zones, viruses and bacteria are destabilized and cracked by collisions with radicals created in the plasma.
All of these cabin air systems are currently being developed and tested for use in airliner cabins but can be scaled easily for use in business jets.
International Water-Guard (IWG) of Burnaby, B.C., has a growing list of clients for its circulating potable water system and recently received an STC for installation in the BBJ.
Equally important, IWG has just received “an order valued at approximately $500,000” for the purchase of an unspecified number of its potable water treatment units from an unidentified business jet manufacturer. IWG declined to identify the customer, but president and CEO David Fox pointed out that it is not the first OEM to contract for what IWG calls the NPS-A6. It is a “long-term procurement item” for installation on the Gulfstream G550 and on Bombardier’s Global 5000. Its function combines filtration and ultraviolet disinfection to deliver water free of potentially harmful bacteria and viruses.
“We’re following the uptick in the industry, and a growing number of buyers are requesting it if it isn’t standard,” said Fox. “More buyers are realizing that ensuring clean water is a major part of the cabin environment.”
Noise is also part of the cabin environment, and a most undesirable part of it, at that. Studies have shown that the high-frequency vibration (another term for noise) to which passengers and crew are subjected can contribute to fatigue and is a major contributing factor to what is commonly known as jet lag.
Dassault is making a major selling point of its efforts to reduce the noise in the cabin of its new Falcon 7X. The company hopes to deliver an airplane in which the noise level is 52 dBSIL (decibel speech interference level) under most flight conditions, comparable to the noise level in a luxury car at 68 mph, according to Falcon aircraft acoustics manager Jean-Marc Pini.
The objective is to reduce noise levels at the medium- and high-frequency range, which have the most adverse effect on conversation.
To achieve the goal, Dassault built dedicated test equipment at its Merignac and Argenteuil facilities to deal with thermal-acoustic issues and worked closely with engine manufacturer Pratt & Whitney Canada and with Lord Corp., a U.S.-based specialist in vibration, shock, motion and noise control. The result is:
• a special felt layer between floor and carpet;
• flexible engine mounts to reduce noise produced by engine vibration;
• and special thermal-acoustic insulation that will retain its acoustic barrier properties in extreme temperatures.
Meanwhile, Pini and his team are looking forward to the first flight of 7X S/N 3 before year-end. The airplane, with a fully completed cabin, will provide a definitive platform to determine if they have been successful.
Lufthansa Technik is also looking into cabin noise reduction as part of a noise- and weight-reduction program for what it calls “the intelligent cabin.” The company has been working both in house and with thermal-acoustic vendors toward this end. Lufthansa engineers believe that an “inner and outer acoustic ring,” in combination with vibration dampers and other measures, will provide a solution.
In growing numbers, customers are expressing a desire for a quieter cabin. “They don’t understand why the interior of their $60,000 Lexus is quieter than the cabin of their $40 million business jet,” said Emon Halpin, president and CEO of Flight Environments.
The Paso Robles, Calif.-based company is currently working on a BBJ project with PATS’ completion center in Georgetown, Del., to produce a BBJ cabin in which the speech interference level is less than 50 dBSIL. In the average luxury car, the dBSIL is typically about 56. On a typical airliner, the dBSIL is in the mid-60s.
“We’re actually writing a BBJ contract requirement for a dBSIL of 49,” said Dominick Scott, v-p of quality and procurement at PATS.
Reducing aircraft cabin noise is more than simply a matter of putting in more layers of “the pink stuff” said Halpin. “It’s a matter of attention to detail, such as where the furniture is placed and how it’s attached and where the pumps and fans and valves are located.”
One of Flight Environments’ recent customers is the owner of an executive/VIP Boeing 747, in which some individuals have actually refused to fly because of the high cabin noise levels. At the owner’s request, Flight Environments set about redesigning a acoustic package for the airplane’s conference center. “We actually got the dBSIL down to the mid-40s,” said Halpin, “so we know what’s possible.”
Halpin’s company is also working on a BBJ refurbishment for a customer for whom they created the original thermal-acoustic package for the airplane five years ago. “He came to us and said he’s having the airplane refurbished, and that if we could get the dBSIL down to the mid-40s, he would be willing to pull out the entire interior to do it.”
“A noisy cabin places a burden on physical stamina, and a quiet cabin is especially important in a head-of-state business jet,” said Scott. And, he added, more and more customers see a quiet cabin as an essential part of the cabin environment.