NW747-400
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Joined: Tue Jun 08, 1999 4:42 am

MD80 And Noise Restrictions

Wed Feb 02, 2005 1:21 pm

New noise restrictions with strict guidelines are likely to be issued soon, and the JT8 powered mad dogs may or may not squeak by. If they are unable to pass any new noise restrictions, would it be feasible to re-engine the MD's with new high bypass engines? Right now they are running on a 2:1 bypass ratio and they sacrifice subsonic fuel economy. New high bypass engines, maybe something near 5:1, would improve noise and help tremendously with fuel efficiency. With Delta and American operating hundreds of mad dogs, it is not financially viable to replace the airplanes outright.

Just a thought...
 
DfwRevolution
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RE: MD80 And Noise Restrictions

Wed Feb 02, 2005 2:01 pm

If they are unable to pass any new noise restrictions, would it be feasible to re-engine the MD's with new high bypass engines?

There was a very long discussion on this exact topic a few weeks back... you might find better details than I can remember by going back and looking for sometihng like "AA MD-80 re-engine," ect...
 
aeroweanie
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RE: MD80 And Noise Restrictions

Wed Feb 02, 2005 2:49 pm

Why reengine them? There already is a certified Stage IV hushkit available.
http://www.jet-md80.com/
 
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lightsaber
Crew
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RE: MD80 And Noise Restrictions

Wed Feb 02, 2005 4:07 pm

Pratt has also developed a mixer to squeak the MD-80 past stage 4 requirements. This is similar to the one in the nozzle of the V2500 or the RR Trents. Note: last I looked they hadn't thrown the $$$ to certify it. So noise will not force the issue.

On another front, the MD-80 engines are fairly low thrust. The BMR-175 or pw6000 would both be ok replacements. At today's oil prices, an engine change would be a close call (it all depends on the retrofit costs vs. estimated fuel and mx savings).

Lightsaber.
"They did not know it was impossible, so they did it!" - Mark Twain
 
bennett123
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RE: MD80 And Noise Restrictions

Wed Feb 02, 2005 9:26 pm

I think that this is more likely in the US than in Europe for two reasons.

1. Europe tends to be more rigid regarding noise.

2. The number of MD80's in Europe is already declining.
 
PSU.DTW.SCE
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RE: MD80 And Noise Restrictions

Wed Feb 02, 2005 11:20 pm

Any new noise restrictions will be phased in. The MD-80's, etc will all be grandfathered in until they are retired. There are simply too many in service, that it is uneconomical to have them all replaced for this before the end of their useable life. These regs primarily will apply to biz jets.
 
AA737-823
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RE: MD80 And Noise Restrictions

Thu Feb 03, 2005 3:25 am

I dunno, the old 732 and DC9 fleets were forced to comply...
 
A350
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RE: MD80 And Noise Restrictions

Thu Feb 03, 2005 3:38 am

Aren't there some more flexible rules like landing fees as a function of noise? AFAIK, we have such rules in Germany. Furthermore, will the rules apply to all airports? I think in the US you have some quite remote airports which don't need such strict noise regulations as airports in urban areas need.

A350
 
bennett123
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RE: MD80 And Noise Restrictions

Thu Feb 03, 2005 7:08 am


My understanding of the CAT 3 Regs, which I assume will form the basis of CAT 4 is that there are a number of tests, approaching, overhead, departing, side etc.

The European rule was that you had to pass every test, the US take on this was that if you passed most and only just failed one or two, then that was OK.

I think that it was partly due to population density, no one is 50 miles from an airport.
 
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lightsaber
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RE: MD80 And Noise Restrictions

Thu Feb 03, 2005 8:01 am

Bennett123,

As the regs are written, you can fail one test by a few db, but as long as you cleared other tests with margin, you can be a CAT 3 or CAT 4. I knew Europe takes a tougher stance, I didn't know the details. Since the ICAO regulations were supposed to be the "end all be all" of noise regulations, it has created friction that individual countries take different interpretations...

There is always a lag between new regulations and enforcement. Right now the airlines are trying to set up the politics so that the US never requires retrofit to CAT 4 (from 3). Personally, I'd like to see a phase out in 15 years (or retrofit), but my opinion and $4 gets you a Latte at Starbucks.  Big thumbs up

Seriously, non-aviation enthusiasts are really annoyed by aircraft noise. How I like to think of the noise regulations:
CAT 1: non-noise regulated. It hurts when these fly over.
CAT 2: If you're in a house, stop your conversation while the plane flies over.
CAT 3: You could yell over the plane if you're talking in the house, but you're not going miss noticing it.
CAT 4: You could yell over the plane if you're outside the house as it flies over.
CAT 5: (proposed, still under ICAO committee) You could still converse outside of the house. This is the first level where the neighbors noisy mower is more annoying than an aircraft.

Please don't get me wrong, I love aircraft. Maybe its because noise regulations would put more $$$ into engine R&D...  Big thumbs up

Lightsaber
"They did not know it was impossible, so they did it!" - Mark Twain