Andrew Doyle/LONDON
HUSHKIT SALES are booming, but the US domestic market is eclipsing that of Europe, highlighting the radically different approaches being taken by the airlines and airports of the two regions.
The major passenger airlines of the USA are finally ordering huge numbers of hushkits, as they shuffle order backlogs for new aircraft while trying to comply with phase-out rules for fleets which do not comply with Stage 3 noise limits (equivalent to Chapter 3 in Europe).
In Europe however, only a handful of hushkits are being sold, partly because fewer non-compliant aircraft are still in operation. European airlines, which have bought hushkits, have mainly done so to boost the resale value of their aircraft, rather than because they plan to keep operating the aircraft in the long term. One of the main factors behind this divergence is a fundamental difference in the way in which the aims of current noise legislation are being interpreted in Europe and the USA.
Some European airports are implementing charge structures, which encourage airlines to operate latest-generation aircraft, which fall well inside Chapter 3 regulations, rather than aircraft, which have been hushkitted and fall marginally inside the limits.
PAYING THE PRICE IN GERMANY
In Germany, for example, airlines operating Chapter 2 aircraft can incur up to 300% higher landing fees than those operating aircraft which meet Chapter 3 requirements. Furthermore, several Chapter 3-compliant types, such as the hushkitted Boeing 737-200, 747-100/200, McDonnell Douglas (MDC) DC-10-10 and MD-80, nevertheless incur landing fees for their operators which are up to 30% higher than for latest-generation aircraft, and may be banned from night flights.
Many of these European airports are disappointed at the failure of the International Civil Aviation Organisation (ICAO) to agree even more stringent noise standards, and have decided to impose their own rules. Therefore, the Chapter 3 aircraft being penalised in Europe generally consist of those which comply marginally, such as aircraft which have been re-certificated, modified and hushkitted, as well as marginally compliant types still in production, such as the MD-80.
"There is quite a difference between Europe and the USA," says Rudolf Moench, performance and operations engineer at Lufthansa, highlighting the complex task of how to calculate the economic benefits of hushkitting. The economic justification for hushkitting a Chapter 2 aircraft to meet Chapter 3 rules appears compelling, because of vastly inflated landing fees, but the aircraft will still incur substantial penalties compared with a latest-generation aircraft.
"It depends on the number of landings you have and at which airports," says Moench. "You have to look at your whole network and see what comes out." Lufthansa is not adversely affected by the rules as it operates few old aircraft - mainly hushkitted 737-200s and 747-200s. Its 737-200s are to be progressively replaced by Airbus A319s. Germany's transport ministry, meanwhile, has drawn up a list of the quietest aircraft types, based on measurements taken around Germany, as a guide for the country's airports. Individual airports can then draw up their own lists, which may vary according to whether they face particular problems with take-off or approach noise, or allow night flights. Airports are free to add types to the list, but cannot remove an aircraft, which appears on both the lists of aircraft acceptable for take-off and landing. According to Mathias Brendle, assistant director for technical and environmental matters at ADV, the German airports association, the lists are designed to differentiate between hushkitted Chapter 2 aircraft and latest-generation types designed and built to fall well inside Chapter 3 limits.
"If you measure the noise emitted by hushkitted ex-Chapter 2 aircraft you really find little difference before and after [hushkitting]," says Brendle. "People will hear the difference between hushkitted Chapter 3 aircraft and those that were born Chapter 3. This is based on noise measurements done by German airports."
Brendle believes that a further tightening of the rules, resulting in a so-called "Chapter 3b", could even lead to a resumption in night flights at the many German airports which ban them. "If we could have this [Chapter 3b], it might be possible that airports would be re-opened at night for Chapter 3b aircraft," he says.
In addition, some airports in Europe will no longer allow the practice of so-called "acoustic trades", whereby an aircraft can exceed the take-off, sideline, or approach noise limits, provided that an exceedance at one of the three measuring points is completely offset by reductions at other points.
These developments all highlight the emerging trend for airports, particularly in Europe, to "-go it alone", following the ICAO Committee on Aviation Environmental Protection's failure to recommend increased stringency after meeting at the end of 1995. Some, such as ADV's Brendle, hope that at least common European Union rules may be agreed in the future.
The International Air Transport Association, for its part, argues that there is "no justification" for an increase in stringency, as it believes that the resulting fall in aircraft market values would severely compromise the airlines' ability to replenish their fleets with new aircraft. One of the reasons that the US carriers have embraced hushkitting is because of economic necessity. They simply cannot afford to buy new aircraft to replace the hundreds of 1970s' types in their fleets. The majority of European carriers can probably justify buying new aircraft because they enjoy higher rates of traffic growth than in the USA, have in the past not been subjected to the same levels of competition and, in some cases, are propped up with government cash.
IMPROVING MD-80 PERFORMANCE
"A lot of European airlines like to change their fleet every 10-15 years," says Dick Jacobson, SAS director of fleet planning and control. "SAS in this regard is closer to the US airlines. We do not see any reason to phase out aircraft just because they are 10-15 years old per se. A US airline has to base its fleet decisions on some kind of financial calculation-in Europe, it is not based on any calculation, but more on what they [European airlines] would like. US carriers are also subjected to a greater amount of competition. I think that this will change in Europe," he adds.
SAS decided in 1995 to hushkit its 24 MDC DC-9-41s, which it plans to continue operating through 2000. It will take delivery of the first of up to 76 737-600s at the end of 1998, initially replacing leased MD-80s and Fokker F28s. The Scandinavian carrier is also looking at options for reducing the environmental impact of its MD-80s, which fall just inside Chapter 3 limits. It operates a fleet, of more than 60 of the type, with an average age of under seven years.
"We are actively looking at improving the environmental performance of the fleet," says Jacobson. On the possibility of hushkitting the MD-80s, he says: "When there is a kit that gives a clear improvement, we would probably do so. However, most research indicates that existing rules on the phase-out of Chapter 2 mean that noise pollution is going to reduce everywhere."
Pratt & Whitney is working on a new 16-lobe advanced-technology mixer and "muffler" tail-cone to reduce noise levels for the MD-80, but says that the upgrade is "still in the test and development stage. Both are currently undergoing full-scale wind tunnel testing. We are working with MDC and the airlines to see if and when it will be introduced as a production item. If we go forward, we would offer it as an OEM [original-equipment-manufacturer] option on new MD-80s, and probably also offer it as a kit," says the company. P&W claims that the new mixer and tail-cone will take the MD-80's noise signature "well below Stage 3".
As ABS Partnership, a joint-venture company between Airborne Express, Burbank Nacelle and San Fran, enjoys steady sales of its DC-9 hushkit, development work is focused on a new 18-lobe mixer which will enable the DC-9-50 to meet Stage 3 limits. Flight-testing of the new kit, which is being developed in conjunction with P&W, is expected to begin in September, followed by the award of a supplemental type certificate (STC) in the first quarter of 1997.
According to Bob Fregeau of ABS, the 18-lobe kit will be pitched at a total market of around 100 DC-9-50s, plus operators of the smaller DC-9-30/40 which require further noise reductions or higher operating weights than are possible with the existing 12-lobe mixer. The 18-lobe mixer will be much easier to install, says Fregeau, because it eliminates the need to increase the size of the tailpipe.
The significantly higher cost of the new mixer, however, is likely to restrict its appeal to a niche market. Northwest Airlines is by far the largest operator of the DC-9-50, with a fleet of more than 30 aircraft, although "- we are talking to anybody that has the -50", says Fregeau.
He acknowledges that the market for the DC-9 hushkit outside the USA is small, saying: "There are not a lot of DC-9s in the world other than in the USA. The [US] airlines just don't have the money to buy new fleets of aircraft."
RAISING 737-200 MTOW
Another significant market is among DC-9 operators based in Central and South America which operate into the USA, some of which also face noise restrictions in their own countries. "Mexico is about to put in place a rule requiring Stage 3," Fregeau believes.
The 737-200 hushkit market, meanwhile, is well established, and rival suppliers AvAero and Nordam of the USA are both working on kits to allow aircraft fitted with the more powerful JT8D-17/17A to be operated at higher weights.
"Our development programme is aimed at filling out the total envelope," says Ronald Suihkonen, director of sales at AvAero. The company does not yet offer a kit, which allows -17/17A-powered 737s to be operated at a 58,160kg maximum take-off weight (MTOW). "Neither we nor Nordam can meet the Stage 3 envelope at that high weight," says Suihkonen. "We expect to be there during 1996."
AvAero has identified 228 in-service aircraft, which are powered by the -17/17A versions of the JT8D. "Considering the current operators of these aircraft, they present a substantial market, although we estimate that fewer than 100 of the 228 are Stage 3 hushkit candidates now, or within three years," he says.
Nordam, meanwhile, is testing a 737-200 low-gross-weight (LGW) kit for the JT8D, which is expected to be certificated in November. The LGW-18 configuration, in common with ABS' new DC-9 kit, will have an 18-lobe mixer, developed jointly by Nordam and P&W, replacing the 12-lobe mixer.
According to Jack Arehart, vice-president for programme development at Nordam, the 18-lobe mixer is "-expected to enable all JT8D-17/17A-powered 737-200s to meet Stage 3 requirements". The LGW-18N kit, which also has the 18-lobe mixer, will be offered for the -7/7B, -9/9A and -15/15A versions of the JT8D.
Meanwhile, development work on Stage 3 hushkits for the Boeing 707 and MDC DC-8-50/61continues. Burbank Aeronautical II (BAC II) expects to complete flight tests of its 707-300 hushkit by early November, gain the first of several STCs in December, and make first deliveries by January 1997. STCs for the DC-8-50/61 are expected to follow in June 1997. Before beginning its 707 and DC-8 hushkit programme, BAC II says that it "-decided several factors must be present to justify both the cost of a hushkit and the ageing-aircraft structural work necessary to make either aircraft economically viable well into the next century".
These were that the hushkitted aircraft should "comfortably" achieve Stage 3 compliance without the use of so-called "acoustic trades", and without reductions in take-off or landing weights, or approach flap settings. There would also be "no substantial degradation in fuel consumption", says the company.
Tom McGuire, vice-president of marketing at BAC II, claims that the company's new kits do not rely on exploiting the acoustic-trade provisions of Stage 3 rules because it has achieved "no exceptions in any category whatsoever".
He adds that BAC II welcomes recent US Federal Aviation Administration moves to qualify the impact of hushkits on fuel consumption. "As of March, to get an FAA STC, you also have to have fuel-consumption tests. We are expecting no fuel-consumption penalty whatsoever," he adds. He claims that the weight penalty of 295kg per nacelle is offset by the improved aerodynamics of the revised nacelle and mixer.
COST-CUTTING 707 OPTIONS
Following consultations with operators, however, BAC II is considering offering a range of options, which could reduce the cost of achieving Stage 3 compliance on the 707. The full kit is projected to cost $3.25 million, but eliminating the respaced inlet guide-vanes from all four engines and the thrust reversers on the outboard engines only could reduce the price per shipset to $2.4 million, according to McGuire. The existing cascade-type reversers are being replaced with more efficient target-type units.
"There is a possibility we may be flying with just the inboard thrust-reversers," says McGuire. "The respaced inlet guide vanes produce a 4dB reduction, but some carriers may not need that type of performance."
Quiet Nacelle (QNC), meanwhile, has completed test-flying its Stage 3 hushkit for the 707, and is awaiting an STC. The hushkit was installed on a P&W JT3D-powered US Air Force Boeing WC-135B (a military version of the 707) for acoustic tests.
Miami-based QNC is hoping for an STC on the 707-100 in September, followed by certification on the heavier -300 in November. The -300 hushkit has a lobed mixer similar to that developed for the company's DC-8 hushkit.
The USAF has ordered one ship-set for an OC-135 Open Skies treaty-verification aircraft and another for a VC-137 military VIP-transport version of the 707-300, to allow the aircraft to be operated from European airfields. QNC claims that it holds letters of intent for an unspecified number of 707 hushkits.
There are around 300 candidate JT3D-powered 707s remaining, the majority of them -300s. A few 707-100s remain in operation, and are flown in the executive role, while the -300 is used primarily for cargo services.
Source: Flight International
