L1329II
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Any MD-80 Engine Retrofits?

Wed Mar 29, 2006 12:18 pm

I remember reading here that AA and maybe DL is looking to retrofit thier MD-80 series with different engines. Has there been any more research and or has any STC's been issues for any retrofit for the 80 series? Also, I am under the impression that the MD-90 was a flop. Any reason for that as well?

Pardon my ignorance, I know this topic has been discussed plenty.
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1337Delta764
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RE: Any MD-80 Engine Retrofits?

Wed Mar 29, 2006 1:17 pm

Quoting L1329II (Thread starter):
I remember reading here that AA and maybe DL is looking to retrofit thier MD-80 series with different engines. Has there been any more research and or has any STC's been issues for any retrofit for the 80 series? Also, I am under the impression that the MD-90 was a flop. Any reason for that as well?

I think that AA might look for new engines for the MD-80s, but not DL. In 10 years, Delta will probably have the MD-80 fleet retired, while AA could be operating them 15-20 more years.
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flydreamliner
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RE: Any MD-80 Engine Retrofits?

Wed Mar 29, 2006 2:15 pm

Quoting 1337Delta764 (Reply 1):
I think that AA might look for new engines for the MD-80s, but not DL. In 10 years, Delta will probably have the MD-80 fleet retired, while AA could be operating them 15-20 more years.

I agree, Delta won't be keeping the MD-80s/MD-90s too much longer. They'll consolidate 4 models into one - the 737-800.

I don't think AA will have the MD-80s 20 years from now. 10 years, probably. The issue they have is this. They sunk a good deal of money into a good sized 737-800 fleet. They want to get as few models in the fleet as possible. I'm not sure they'll wait till Y1 to replace the MD-80s.
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spartanmjf
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RE: Any MD-80 Engine Retrofits?

Wed Mar 29, 2006 2:42 pm

Maybe NW will do the retrofits - they can make a great DC9 replacement!
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September11
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RE: Any MD-80 Engine Retrofits?

Wed Mar 29, 2006 2:51 pm

AA is flying most recent MD-80s off production line, specifically MD-83s acquired from TWA. They will be in service for years to come. Engine retrofits are not suggested on MD-83s at this point?

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[Edited 2006-03-29 06:55:37]
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lightsaber
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RE: Any MD-80 Engine Retrofits?

Wed Mar 29, 2006 4:35 pm

Quoting September11 (Reply 4):
AA is flying most recent MD-80s off production line, specifically MD-83s acquired from TWA. They will be in service for years to come. Engine retrofits are not suggested on MD-83s at this point?

The younger the airframe, the more sense an engine upgrade makes.

The reality is, as the years go by and the MD-80 airframes age, the present value of an engine retrofit drops. There are basically only two candidates: The RR 715 and Pratt PW6000. Its all going to come down to AA taking the initiative or not. I'm biased toward the pw6000!  bigthumbsup  It will all come down to purchase price of the engine/nacelle and weight/balance engineering issues will determine if this goes forward. Since the JT8D has a TSFC of (IIRC) .737, there is a ton of room for improvement, over a 20% drop in fuel burn would dramatically change the MD-80's mission profile.  Smile

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RE: Any MD-80 Engine Retrofits?

Wed Mar 29, 2006 5:23 pm

Quoting Lightsaber (Reply 5):
ince the JT8D has a TSFC of (IIRC) .737, there is a ton of room for improvement, over a 20% drop in fuel burn would dramatically change the MD-80's mission profile.

Are yu sure that isn't a figure for the JT8-7/9/15 (low bypass) versions, and not for the -2XX series high bypass? I thought I had seen estimates closer to 10% for fuel savings, which likely pencils out to a near-wash given the age of most of the airframes.

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RE: Any MD-80 Engine Retrofits?

Thu Mar 30, 2006 1:34 am

Quoting Sllevin (Reply 6):
Are yu sure that isn't a figure for the JT8-7/9/15 (low bypass) versions, and not for the -2XX series high bypass? I thought I had seen estimates closer to 10% for fuel savings, which likely pencils out to a near-wash given the age of most of the airframes.

I found a link that matched my memory for the -200.
http://www.alair.com/Commercial/jt8d-2.html

JT8D's are great engines but gas hogs by today's standards.

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RE: Any MD-80 Engine Retrofits?

Thu Mar 30, 2006 1:36 am

Quoting L1329II (Thread starter):
I remember reading here that AA and maybe DL is looking to retrofit thier MD-80 series with different engines. Has there been any more research and or has any STC's been issues for any retrofit for the 80 series? Also, I am under the impression that the MD-90 was a flop. Any reason for that as well?

I'm not really sure about any STC's being issued. But I have heard AA has at least studied it. If it were to happen my money would be on the BR715. It's light, it's been fitted to a DC-9 airframe and it's an RR product.

As for the MD-90 being a flop that was due mainly to it's unrelaiablity when it first entered service. Mainly attributed to it's electrial syste,.
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RE: Any MD-80 Engine Retrofits?

Thu Mar 30, 2006 1:48 am

Quoting Spartanmjf (Reply 3):
Maybe NW will do the retrofits - they can make a great DC9 replacement!

Hahaha, nope. NW has never been interested in MD-80s. They're replacing DC-9 with A319 and EMB-170/175/190 in the future.

Quoting Lightsaber (Reply 5):
The younger the airframe, the more sense an engine upgrade makes.

The reality is, as the years go by and the MD-80 airframes age, the present value of an engine retrofit drops. There are basically only two candidates: The RR 715 and Pratt PW6000. Its all going to come down to AA taking the initiative or not. I'm biased toward the pw6000! bigthumbsup It will all come down to purchase price of the engine/nacelle and weight/balance engineering issues will determine if this goes forward. Since the JT8D has a TSFC of (IIRC) .737, there is a ton of room for improvement, over a 20% drop in fuel burn would dramatically change the MD-80's mission profile.

Even if AA's frames are new, fleet commonality counts for a lot. They've started to phase in 737-800s to start taking up MD-80 routes. Putting new engines on MD-80 would require a lot of engineering. Even the 200 series JT8D's are not terribly high bypass, nowhere near like the CFM56-5 or CFM56-7's. PW6000 might work, but the only modern high bypass turbofan that the engineering has already been done for is the IAE V2500 - that was used on MD-90. MD-80 isn't that much smaller, IAE V2500 could work. The question is if anyone really cares enough to do it.
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RE: Any MD-80 Engine Retrofits?

Thu Mar 30, 2006 1:49 am

Quoting Sllevin (Reply 6):
Are yu sure that isn't a figure for the JT8-7/9/15 (low bypass) versions, and not for the -2XX series high bypass?

There ARE no high bypass JT8D's.
2:1 is NOT high bypass.
And that's the reason a retrofit would make such sense- put something on there that blows some air!!!
 
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RE: Any MD-80 Engine Retrofits?

Thu Mar 30, 2006 2:43 am

If someone has too much time on their hands and is so inclined, I'd love to see a side by side comparison of JT8D, RR 715 and Pratt PW6000. Thrust, weight, fuel consumption, bypass ratio, size and all that good stuff.

Also what is TSFC?
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aeroweanie
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RE: Any MD-80 Engine Retrofits?

Thu Mar 30, 2006 3:14 am

Why reengine an elderly airframe? The mod would probably cost more than the airframe hull value. To meet noise regulation, there are two hush kits available - Jet Engineering/Goodrich's and Aviation Fleet Solutions' (they got their STC last week).
 
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RE: Any MD-80 Engine Retrofits?

Thu Mar 30, 2006 5:33 am

Both CFM56 and V2500 are too large and heavy. They would create a serious balance problem. Having to fly around with a thousand lbs concrete block in the nose would not only take away much of the gain, but combined with the heavier engines it would seriously increase empty weight and that way reduce the airframe's useful load for fuel and payload.

That leaves us with high powered versions of BR-715 and the PW6000.

But whatever way we go, maybe one major obstacle will be that it will be a change from mechanical to FADEC controlled engines. That will mean a lot more changes to the plane than just putting on new engines. A new certification procedure may be long and costly.

So I doubt that it will happen.

Quoting L1329II (Thread starter):
Also, I am under the impression that the MD-90 was a flop. Any reason for that as well?

No, not so. MD-90 is arguably the finest plane ever made.

It had its teething problems in the beginning. It showed all the signs of a product which was too hastily introduced by a company without economic resources. The problems have been corrected now.

Sitting in the forward half of the cabin of an MD-90 you enjoy the quietest and most comfortable ride of any airliner in the world.

Its only problem was that it competed head on with the B737-800, and when the MDD money tank ran dry, then there was nobody but Boeing to take over the program. Of course they could not continue two competing programs. And of course they could not scrap their all new entire family of 737NGs.

My theory: Douglas and MDD made too good airliners. They were more expensive to produce than the competitors, but they were unable to obtain a substantially higher price. Ends didn't meet. Any proofs?

Why can NW still fly fuel guzzling, hushkitted DC-9s these days? They must be immensely cheap and efficient to maintain.

Why is the DC-8 practically the only successfully re-engined civil airliner? And why do they seem to last for ever as freighters? They are 40 years old and nobody talks about retirement.

DC-10s are practically all (at least the -30 model) being converted at considerable cost to MD-10 freighters, while similarly aged products from the competitors are being scrapped.

There is a constant and high demand for pax MD-11s being released for freighter conversion.

There must be a reason.

Further proofs? SAS planned on exchanging their large DC-9 fleet with loads of MD-90. They got only 8 before production was ended. Then they bought 50+ 737NGs, got disappointed, and continued buying A320 family planes.

But they have been very reluctant to shed those 8 MD-90 even if they carry their own type rating and must be a terrible headache in crew planning.

I have heard that they try the best they can to let all MD-90 crews carry double type rating - being rated for MD-80 in addition to MD-90. That adds some flexibility, but at some not insignificant cost.
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RE: Any MD-80 Engine Retrofits?

Thu Mar 30, 2006 6:24 am

Quoting LMP737 (Reply 8):
it's been fitted to a DC-9 airframe

Any pictures of that plane?

Quoting FlyDreamliner (Reply 9):
IAE V2500 could work

I was thinking that too, but it might be too heavy.

Biggest problems I see in doing the conversion are weight, FADEC/avionics/airframe re-engineering, certification, and of course  dollarsign 

Also, since MDD is dead, who would do the engineering part, Boeing?
 
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RE: Any MD-80 Engine Retrofits?

Thu Mar 30, 2006 7:20 am

Quoting FLY2HMO (Reply 14):
Also, since MDD is dead, who would do the engineering part, Boeing?

The customer of course  Wink If you have 350+ planes in your fleet, the cost of certification can be pretty nicely amortized.

If re-engineing can give those MD-80s another 20 years at a cost lower than buying a new product (with costs adjusted for lifetime of new airliner) it's worth looking at.
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RE: Any MD-80 Engine Retrofits?

Thu Mar 30, 2006 8:07 am

Quoting FLY2HMO (Reply 14):
Quoting LMP737 (Reply 8):
it's been fitted to a DC-9 airframe

Any pictures of that plane?


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Fly2HMO
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RE: Any MD-80 Engine Retrofits?

Thu Mar 30, 2006 11:52 am

I don't think that's it Aerowinnie, that's a 717  Smile

http://registry.faa.gov/aircraftinquiry/NNumSQL.asp?NNumbertxt=922me

Although I do understand the 717 is a DC9 with a glass cockpit, decent engines, and a beaver tail.
 
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RE: Any MD-80 Engine Retrofits?

Fri Mar 31, 2006 12:55 am

Just to add my 2 (or so) cents
The 717 is not much more than a 30 series 9 with pretty avionics so AeroWeanie's point is valid. In fact DAC went back to the DC9 wing because of the ice fod problem with the MD80 wings.
The 715 engine has serious reliability issues which is the principal reason for the 717's demise.
The V2500 engine is the only current realistic candidate. Looking at the mounting and CG on the MD90 it doesn't seem that big a mod compared to some others. Just putting a heavyweight hushkit on a 727F requires almost a complete empenage rebuild.
Just one man's opinion mind you...
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RE: Any MD-80 Engine Retrofits?

Fri Mar 31, 2006 2:11 am

Quoting Prebennorholm (Reply 13):
No, not so. MD-90 is arguably the finest plane ever made.

It had its teething problems in the beginning. It showed all the signs of a product which was too hastily introduced by a company without economic resources. The problems have been corrected now.

Sitting in the forward half of the cabin of an MD-90 you enjoy the quietest and most comfortable ride of any airliner in the world.

The first airliner I ever worked on was an MD-90. So I guess you can say I have a soft spot for the aircraft. However I have to admit it's one of the more temperamental aircraft I have worked on. Even with a lot of the bugs that troubled it in it's early years having been worked out. With that said it's a good looking airplane that's gives you the quietest and smoothest ride of any airliner.

Quoting FLY2HMO (Reply 14):
Any pictures of that plane?

Of course, just look at any picture of the 717!  Wink
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RE: Any MD-80 Engine Retrofits?

Fri Mar 31, 2006 2:30 am




Quoting LMP737 (Reply 19):
With that said it's a good looking airplane that's gives you the quietest and smoothest ride of any airliner.

That's a pretty strong statement...is it really that much nicer? I've never been in one.




2H4


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CRJonBeez
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RE: Any MD-80 Engine Retrofits?

Fri Mar 31, 2006 2:44 am

Quoting AA737-823 (Reply 10):
There ARE no high bypass JT8D's.
2:1 is NOT high bypass.

good call! IIRC, the standard consideration for high bypass is 5.1

the JT9D, though certainly not used on the mad dog, was a high bypass P&W.

quiztime hotshots! what US plane received the first high bypass engines???
 
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RE: Any MD-80 Engine Retrofits?

Fri Mar 31, 2006 2:45 am

Quoting 2H4 (Reply 20):
That's a pretty strong statement...is it really that much nicer? I've never been in one.

Of course my statement is just an opinion. However my experience so far is that the MD-90 has the smoothest, quietest ride of any airliner I have been on. Even in back where traditionally on th MD-80 things get a bit noisier.
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RE: Any MD-80 Engine Retrofits?

Fri Mar 31, 2006 3:08 am




Quoting LMP737 (Reply 22):
However my experience so far is that the MD-90 has the smoothest, quietest ride of any airliner I have been on.

Cool. It would be interesting to see a graphic comparison of cabin noise between all airliners currently in use. Maybe a sampling of the front, center, and the aft portions of each cabin.




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RE: Any MD-80 Engine Retrofits?

Fri Mar 31, 2006 7:26 am

Quoting 2H4 (Reply 23):

Cool. It would be interesting to see a graphic comparison of cabin noise between all airliners currently in use. Maybe a sampling of the front, center, and the aft portions of each cabin.

The real trick would be to get an independent entity to perform it. If you ask the manufacturers their plane is quieter...
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RE: Any MD-80 Engine Retrofits?

Sun Apr 02, 2006 2:45 pm

Quoting 2H4 (Reply 23):
Cool. It would be interesting to see a graphic comparison of cabin noise between all airliners currently in use. Maybe a sampling of the front, center, and the aft portions of each cabin.

I don't know where to find it, but I've seen an FAA chart with this data. The MD-90 had the quietest cabin of any jetliner in the world until you got to the last 25% of the cabin. I remember the 717 and 328JET also being in the top 5.
 
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RE: Any MD-80 Engine Retrofits?

Sun Apr 02, 2006 7:29 pm

Quoting FlyDreamliner (Reply 9):
IAE V2500 could work.

Not really, it doesn't turn down well to the low thrust leveles the MD-80 family would required. We're talking 18k to 22k for the MD-80's. This is RR 715 (a la 717) or pw6000 territory. The V2500 is a great engine for 24k+, not at the MD-80's low required thrust levels.

Quoting AeroWeanie (Reply 12):
Why reengine an elderly airframe? The mod would probably cost more than the airframe hull value. To meet noise regulation, there are two hush kits available - Jet Engineering/Goodrich's and Aviation Fleet Solutions' (they got their STC last week).

 checkmark  I was very enthusiastic about a MD-80 engine upgrade a year or two ago. But... with both Airbus and Boeing going at it for evey single isle order, the drop in new airframe purchase prices has made retrofits less economical. I'd love to see the retrofit, but I consider the chance unlikely.  Sad Heck, AA is talking about scrapping their oldest MD-80's due to high MX costs. its not that the MD-80 has high maintenance costs, its that once airframes reach a certain life they all see the maintenance costs rise.

Besides, if Boeing does ramp up a 2nd 737 line, there would then be capacity to replace some MD-80's with 738's. e.g, Both DL and AA are 738 operators. I'm sure airbus will make line space if they could steal an MD-80 operator to their single isle product. (e.g., production off the future line in china)

Quoting MD-90 (Reply 25):
he MD-90 had the quietest cabin of any jetliner in the world until you got to the last 25% of the cabin.

But the back is where I always seem to get to sit.  Sad

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RE: Any MD-80 Engine Retrofits?

Wed Apr 19, 2006 9:16 pm

Quoting FlyDreamliner (Reply 2):
don't think AA will have the MD-80s 20 years from now. 10 years, probably.

If American gets 35 new 738 pr year starting this year they could replace all their MD-80 in a 10 year time. That also means there will be 35 MD-80 available each year in that timeframe. Now who will take them?

Quoting Lightsaber (Reply 5):
The reality is, as the years go by and the MD-80 airframes age, the present value of an engine retrofit drops. There are basically only two candidates: The RR 715 and Pratt PW6000. Its all going to come down to AA taking the initiative or not. I'm biased toward the pw6000! It will all come down to purchase price of the engine/nacelle and weight/balance engineering issues will determine if this goes forward. Since the JT8D has a TSFC of (IIRC) .737, there is a ton of room for improvement, over a 20% drop in fuel burn would dramatically change the MD-80's mission profile.

Lightsaber

Lightsaber: Do you know what amount of money we are talking about pr frame? Said that about 300 MD-80 airplanes will be retrofited?
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RE: Any MD-80 Engine Retrofits?

Wed Apr 19, 2006 11:33 pm

Quoting OyKIE (Reply 27):
If American gets 35 new 738 pr year starting this year they could replace all their MD-80 in a 10 year time. That also means there will be 35 MD-80 available each year in that timeframe. Now who will take them?

My guess that maybe a handfull will be picked up by small carriers overseas. The rest will end up as beer cans.

Here's what I think is going to happen. AA is not scheduled to take delivery of anymore 737's until January 2013. By then I suspect that Boeing will have already launched a succesor to the 737. Or at the very least be very close to launching one. By waiting until 2013 AA might be in a perfect position to be a launch customer for it. Then they won't have to worry about having to replace a couple hundred 737's.

Quoting OyKIE (Reply 27):
Lightsaber: Do you know what amount of money we are talking about pr frame? Said that about 300 MD-80 airplanes will be retrofited?

If it were to happen, and I would be suprised if it did, only a portion of the MD-80 fleet would be retrofited. AA would have to figure out how long the engine would have to be on the airframe before it paid for itself. Not all of AA's 300+ MD-80's would have enogh life left in them to make it worth while.
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RE: Any MD-80 Engine Retrofits?

Thu Apr 20, 2006 2:50 am

Quoting Starlionblue (Reply 11):
Also what is TSFC?

Thrust specific fuel consumption in lbm (fuel) per hour per lbf of thrust. Number range from 0.510 (rumored GEnX/Trent 1000), 0.575 for the V2500 (on the A320/321), 0.596 for the best of the CFM-56 family (~7% higher for the worst), 0.737 for the JT8D-200 family, a little higher for the JT8D-15/17/19, and even up to 1.2 for the oldest turbojets.

The reason one uses TSFC is that each airframe tends to need a certain amount of thrust at cruise. e.g., about 4,500 lbf for an MD-80, 8,500 for a 757, and 11,500 lbf for a 747. Its always "about" due to airframe varition, load, amount of fuel left (thrust required drops during cruise as weight drops due to fuel burn). TSFC is a function of engine technology *and* size. Smaller engines suffer inefficiency penalties more than larger engines. Hence the trend to twins (amoung other reasons).

I like this site for its links. The info is pretty accurate, if sparse. Man, I miss the proprietary tables I used to work with... But I haven't found an accurate web site with any fraction of that detail. Hit the "menu" button to navigate.

http://www.alair.com/Commercial/jt8d-2.html

Quoting OyKIE (Reply 27):
Lightsaber: Do you know what amount of money we are talking about pr frame? Said that about 300 MD-80 airplanes will be retrofited?

Depends on the engine. Pratt would probably sell PW6000 at cost or even a small loss (planning to make it up on parts). Engine: $1.5 million each (maybe less, but I'm not allowed to say...). Nacelle: Another $1million. The issue is the recirtification and engineering modifications. I would guess $2million/airframe. But please understand that is at best a SWAG. So we're talking $5 million/airframe (best case). I do assume 150+ airframes to retrofit where the initial engineering/cirtification costs are so well amortized that its small change. For less than 100 airframes, the cost would go up noticably.

For the BMR 715, the nacelle would be cheaper but "a little birdie" informs me that the engines cost more to build, so the costs are nearly a wash. While the BMR 715 would struggle on the MD-80... its possible.

Again, the V2500 on the MD-80 has dropped below its minimal viable cruise thrust. The fuel efficiency (TSFC) would just suck.

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RE: Any MD-80 Engine Retrofits?

Thu Apr 20, 2006 5:28 am

Quoting Prebennorholm (Reply 13):
Both CFM56 and V2500 are too large and heavy. They would create a serious balance problem. Having to fly around with a thousand lbs concrete block in the nose would not only take away much of the gain, but combined with the heavier engines it would seriously increase empty weight and that way reduce the airframe's useful load for fuel and payload.

That leaves us with high powered versions of BR-715 and the PW6000.

Once again, I have to point my finger to the MTU website.
The PW6000 is actaully HEAVIER than the CFM56 ! The CFM56 is lighter than the JT-8D-200 while the IAE V2500 is heavier than everything else.
IIRC, the MD-90´s forward fuselage was stretched compared to that of the MD-80 because the weight of the heavier engines had to be countered.

See the MTU website for engine weights except RR BR-715:

http://www.mtu.de/en/programme/zivil/index.html
Exceptions confirm the rule.
 
Oykie
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RE: Any MD-80 Engine Retrofits?

Thu Apr 20, 2006 8:12 pm

Quoting Lightsaber (Reply 29):
Thrust specific fuel consumption in lbm (fuel) per hour per lbf of thrust. Number range from 0.510 (rumored GEnX/Trent 1000), 0.575 for the V2500 (on the A320/321), 0.596 for the best of the CFM-56 family (~7% higher for the worst), 0.737 for the JT8D-200 family, a little higher for the JT8D-15/17/19, and even up to 1.2 for the oldest turbojets.

Do you have the TSFC for the PW600 and RR-715?

Quoting Lightsaber (Reply 29):
Depends on the engine. Pratt would probably sell PW6000 at cost or even a small loss (planning to make it up on parts). Engine: $1.5 million each (maybe less, but I'm not allowed to say...). Nacelle: Another $1million. The issue is the recirtification and engineering modifications. I would guess $2million/airframe. But please understand that is at best a SWAG. So we're talking $5 million/airframe (best case). I do assume 150+ airframes to retrofit where the initial engineering/cirtification costs are so well amortized that its small change. For less than 100 airframes, the cost would go up noticably.

Thank you for your numbers. So if AA and others like DL and SK goes through with this it means that they need to have the airplanes in service for about 10 years after the modification in order to make this upgrade economical, compared to buying a new one for about 30 million USD after discount?
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Starlionblue
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RE: Any MD-80 Engine Retrofits?

Thu Apr 20, 2006 10:03 pm

Quoting FlyDreamliner (Reply 2):
I don't think AA will have the MD-80s 20 years from now. 10 years, probably. The issue they have is this. They sunk a good deal of money into a good sized 737-800 fleet. They want to get as few models in the fleet as possible. I'm not sure they'll wait till Y1 to replace the MD-80s.

With a fleet the size of AA's, existing models such as the 738 are not terribly relevant. You should not base the decision for 300 new aircraft on 80 you already have. 300 new aircraft will give you economies of scale well beyond what most airlines have in their entire fleets. Existing facilities, pilots and so forth do not have a big impact on cost on this scale.

In the same way, the large 738 fleet AA has can stand on its own cost wise.
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MX757
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RE: Any MD-80 Engine Retrofits?

Fri Apr 21, 2006 3:58 pm

Quoting FLY2HMO (Reply 17):
Although I do understand the 717 is a DC9 with a glass cockpit, decent engines, and a beaver tail.

I call them DC-9NGs. Wink

Quoting Starlionblue (Reply 15):
Quoting FLY2HMO (Reply 14):
Also, since MDD is dead, who would do the engineering part, Boeing?

The customer of course If you have 350+ planes in your fleet, the cost of certification can be pretty nicely amortized.

Boeing still handles engineering issues for MDD products. It's called Boeing Douglass Products Division.

Boeing was developing a MD-80 freighter conversion program but I think they dropped it. It used to be posted on their website but I haven't been able to find the article in quite awhile.

I also have never seen anything on Boeing's site that ever talked about replacing the JT8Ds with a high bypass engine.
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MD-90
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RE: Any MD-80 Engine Retrofits?

Wed Apr 26, 2006 2:36 pm

Quoting MX757 (Reply 33):
Boeing was developing a MD-80 freighter conversion program but I think they dropped it.

It's not good to have a freight door in the front with cargo that has to be pushed to the rear of a T-tail aircraft. Causes loading problems. The 727 gets around this by having a rigid airstair that doubles as an integral aircraft stand. The MD-80s' fold-up airstairs can't serve the same function.
 
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LTU932
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RE: Any MD-80 Engine Retrofits?

Wed Apr 26, 2006 5:06 pm

Quoting FlyDreamliner (Reply 9):
Hahaha, nope. NW has never been interested in MD-80s. They're replacing DC-9 with A319 and EMB-170/175/190 in the future.

They did have MD-80s at one point but phased them out and kept the fully paid for DC-9s.  Wink

Quoting Lightsaber (Reply 29):
Depends on the engine. Pratt would probably sell PW6000 at cost or even a small loss (planning to make it up on parts). Engine: $1.5 million each (maybe less, but I'm not allowed to say...). Nacelle: Another $1million. The issue is the recirtification and engineering modifications. I would guess $2million/airframe. But please understand that is at best a SWAG. So we're talking $5 million/airframe (best case). I do assume 150+ airframes to retrofit where the initial engineering/cirtification costs are so well amortized that its small change. For less than 100 airframes, the cost would go up noticably.

What about modifications to the flightdeck? If a CFM56 was used, this would mean the MD-80s need a modified cockpit without EPR gauges, and if the BR-715 is installed, it might need a gauge for the N3 (if the BMW-RR BR715 is three spool like other Rolls Royce engines). There's lots more to re-engining an aircraft than just the engines and nacelles.
 
A342
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RE: Any MD-80 Engine Retrofits?

Thu Apr 27, 2006 3:45 am

Quoting LTU932 (Reply 35):
(if the BMW-RR BR715 is three spool like other Rolls Royce engines)

No it isn´t. All RR engines assembled in Germany are twin-spool. Recently the Tay assembly line was moved to Germany because Dahlewitz will be the RR competence centre for all twin-spool engines bigger than the AE3007.
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lightsaber
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RE: Any MD-80 Engine Retrofits?

Fri Apr 28, 2006 4:04 am

Quoting OyKIE (Reply 31):
Do you have the TSFC for the PW600 and RR-715?

Alas, I don't. Well, I'm a little NDA "tongue tied" on the PW6000. When I find a good link, I'll share. But I haven't found one that isn't anything more than a wild guess. For the RR-715, its a good engine, but its been five years since I studied it... so I'll admit to forgetting the exact number. Sorry... But I'd rather not post miss-information.

Quoting OyKIE (Reply 31):
Thank you for your numbers. So if AA and others like DL and SK goes through with this it means that they need to have the airplanes in service for about 10 years after the modification in order to make this upgrade economical, compared to buying a new one for about 30 million USD after discount?

10 to 15 years is a good estimate. However, the pricier oil gets, the more sense it makes to go and buy new.  Sad There just are too many improvements in newer airframes. Look how few have been re-engined.  Sad

Quoting LTU932 (Reply 35):

What about modifications to the flightdeck? If a CFM56 was used, this would mean the MD-80s need a modified cockpit without EPR gauges, and if the BR-715 is installed, it might need a gauge for the N3 (if the BMW-RR BR715 is three spool like other Rolls Royce engines). There's lots more to re-engining an aircraft than just the engines and nacelles.

 checkmark  I put that in the $2million/airframe. So the actual cost might be as high as $8 million/airframe. That high... says go out and buy new. As I noted earlier, I doubt there will be an MD-80 retrofit at this point. With a 2nd 737 line opening, I would think that AA/DL could get sweet deals on 738's. Either that or they'll wait for the 737RS.

Oh, as A342 noted, the BR715 is a double spool. Triple spools don't gain great efficiencies until > 60,000 lbf thrust. Below that, the complexity/weight isn't worth it. Above that thrust, their inherent efficiencies make them light (due to fewer stages being required to do the same work as compressor and turbine efficiencies are improved on the intermediate spool operating at a more ideal mach number/(feel free to think RPM)). Note: I know RR has worked on getting the components simpler and more compact. So maybe 40k thrust is the new level that above triple spools gain their legs. Heck, it could be as low as 30k. But not 20k. But GTF's scale down that low.  bigthumbsup 

Note:due to the FADAQ's on the BR715/PW6000, the re-engineering of the airframe isn't as bad as some older retrofits. Compicated? Yes. Expensive? Yes. Worth it? I doubt it.

The CFM, like all gas turbines, has poor performance at thrust levels that far below its design. Its a poor choice for the MD-80. Only the BR-715 and PW-6000 are at the correct thrust levels to have decent efficiency. Even the V2524 would have poor efficiency down at the 18k to 21k needed for the MD-80 (takeoff).

I strongly believe that $70+/bbl oil is going to result in airframes going from a previous 30 year average life down to 20 years.

Lightsaber
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F14D4ever
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RE: Any MD-80 Engine Retrofits?

Sat Apr 29, 2006 11:05 pm

Quoting CRJonBeez (Reply 21):
quiztime hotshots! what US plane received the first high bypass engines???

Lockheed C-5 Galaxy, with General Electric TF39s. Approx. 8:1 bypass ratio.
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