MD90-30 im klassischen Farbkleid der SAS/Courtesy and Copyright: md80design

Courtesy: SAS Flight Ops.

Courtesy: SAS Scandinavian Airlines

Courtesy: Michael Carter

Kurz nachdem SAS zwei ihrer sechs Optionen für MD-90 recht überraschend für die Fachwelt in Festbestellungen umwandelte, warb McDonnell Douglas mit dieser Nachricht u.a. mit dieser deutschsprachigen Werbeanzeige. Zu diesem Zeitpunkt war aber mehr oder weniger deutlich, daß McDonnell Douglas dennoch massiv Marktanteile verlor und weiter verliert/Courtesy: McDonnell Douglas

Dieses SAS-Werbevideo von 1997 zeigt kurz die MD-90 außen und innen...

http://www.youtube.com/watch?v=NIYLtZ3dSeo

MD90-30 im aktuellen Farbkleid der SAS/Courtesy and Copyright: md80design

Courtesy: Alexander Portas                                    Bordtoilette/Courtesy: SAS Scandinavian Airlines

Courtesy: SAS Scandinavian Airlines

The World’s Least Noisy Large Commercial Aircraft

MCDONNELL DOUGLAS MD90-30

Passengers: 141 (SAS version)

Engines: 2 International Aero

Engines turbofan V2500-D5

Cruising speed: 815 km/h

Range: 2,800 km

Fuel consumption: 4.1 l/100 ASK

Number in SAS fleet: 8 (from 1997)

A meter is a meter and a kilo is a kilo. But “noise” is defined in completely different terms, depending on who is experiencing it and under what circumstances. For a per-son who has just gone to bed, the barely audible drip of a faucet can sabotage a whole night’s sleep, while the fortissimo of a symphony orchestra – close to the pain threshold – is regarded as a pleasure by the concertgoer.

The nature of the sound can also mean more than its actual intensity. Sudden, un-expected sounds are more unpleasant than regular noise – which may even, in some cases, be perceived as soothing, e.g. waves washing in over a beach. On the hand, the constant drone of a ventilation system or whirr of a fan can cause fatigue and impair a person’s performance. Perception of aircraft noise includes other factors as well, For example, surveys have shown that people’s fear of accidents makes aircraft noise more irritating than noise from such sources as road traffic. Such comparisons with other modes of transportation involve weighing noise in-tensity against the number of people ex-posed to it. Aircraft noise affects only those who live immediately adjacent to airports, and then only during takeoff and landing, while road and rail traffic cause noise throughout their respective networks, which, for those who live near a major high-way, continues virtually 24 hours a day.

Most of a jet airplane’s noise is pro-duced in three ways. First, the rapidly ex-pelled hot air from the engine collides with stationary, cooler masses of air behind the engine. The second source is the turbu-lence that arises around the wings, fins and landing gear. Thirdly, there are me-chanical vibrations in the engine itself. Re-ducing noise from these sources is the task of the aircraft manufacturers. Their ef-forts have culminated in SAS’s latest air-craft, which is illustrated on this page. Airport owners and operators – often the aviation authority of the country con-cerned – also help to reduce the surround-ing residents’ noise annoyance. One means of doing so is, using traffic restrictions and noise charges, to limit the use of older, noisy aircraft. Others are to restrict flight density (especially at night) and to regu-late the approach for landing and climb after takeoff (e.g. regulations on reducing thrust at a particular altitude during as-cent from an airport).

The airlines are committed – in accor-dance with international regulations, e.g. EU directives – to replace their old air-craft with modern, low-noise models. In SAS, such aircraft make up 81% of the fleet, and by the year 2000 the remaining 19% will have been replaced. In the new generation of jet aircraft, the noise level has been reduced by 8–10 dB, which cor-responds to a halving of perceived noise, and the noise from SAS’s new MD-90s is as much as another 4-6 dB below this level. SAS’s new short-haul and medium-haul aircraft, put into service on November 11, 1996. is by far the least noisy of present-day large commercial aircraft. The noise level for the MD-90 is, at best, around 11 dB below current certification limits, the “Chapter III regulations”, and thus well short of the new limits under discussion, which may mean lowering the Chapter III regulations by a further approx. 3 dB. In economic terms, this means that the aircraft complies with all airport restric-tions concerning noise and may therefore be utilized with unlimited flexibility in SAS’s route systems, and also that the costs of noise charges are minimized. The MD-90 is noise-optimized in the cabin as well. Compared with its prede-cessor, the MD-80, cabin noise from the engines is 5 dB lower.

LOWER CABIN NOISE

Cabin noise is reduced by:

• The low noise level from the engine.

• A low-vibrating engine design and vibration-absorbing engine attachments.

• A body design that avoids the resonance fre-quencies of the rotor.

• Elimination of the thumping noise at the rear of the aircraft that may be caused by unsyn-chronized engines.

AUTOMATIC THROTTLE

Fully automatic throttle option which, with high precision, reduces thrust to a preset level at a particular altitude, thereby elimi-nating unnecessary noise.

Courtesy: SAS Scandinavian Airlines

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