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Feasibilty Of Re-engining Modern Twin Jets  
User currently offlinestuckontarmac From United States of America, joined Jul 2013, 11 posts, RR: 0
Posted (1 year 2 weeks 6 days 20 hours ago) and read 5565 times:

Greetings, I did not see a post on this

What is the feasibility of a re-engine on the newer twins like the 777 and A330? With the newest engines offering excellent economics wouldn't it be possible for cost conscious operators to extend the life of their existing fleets with out replacing them outright with the new 787 and A350 airframes. The DC-8-60 really was able to earn its keep far longer than expected with the CFM and it would seem to be an excellent move with the twins now in service.

12 replies: All unread, jump to last
 
User currently offlineDocLightning From United States of America, joined Nov 2005, 19515 posts, RR: 58
Reply 1, posted (1 year 2 weeks 6 days 20 hours ago) and read 5562 times:

The 777 is going to get a re-engine called the 77X. The A330 does not need a re-engine because it is being replaced by the A350. A re-engined A330 will not be as efficient as an A350.

User currently offlinerampbro From Canada, joined Nov 2012, 203 posts, RR: 0
Reply 2, posted (1 year 2 weeks 6 days 20 hours ago) and read 5513 times:

What the OP is asking about is putting new engines on existing frames. 'Re-engine' is perhaps a less effective phrasing than 'engine upgrade'.

User currently offlineKarelXWB From Netherlands, joined Jul 2012, 11247 posts, RR: 33
Reply 3, posted (1 year 2 weeks 6 days 20 hours ago) and read 5461 times:

For the A330, it makes no sense. Imagine a new engine which burns 15% less fuel. The engine will be heavier and the wing will need to be reinforced, which will also increase the weight. You will eventually only get something around 10% gain in fuel burn, so the whole airframe will still burn 10 to 15% more fuel than an A350.

Nobody will buy such an airframe once both 787 and A350 become largely available. An engine update would be an very expensive, short term solution (if there is time to develop such an engine in the first place).



Only two things are infinite, the universe and human stupidity. And I'm not sure about the universe.
User currently onlineB757forever From United States of America, joined May 2010, 400 posts, RR: 3
Reply 4, posted (1 year 2 weeks 6 days 20 hours ago) and read 5461 times:

What you say about the DC8 is correct because the huge leaps in technology and efficiency from the original engines to the CFMs more than paid the cost of modification. With newer aircraft such as the 777 and 333 the gap in technology and efficiency of the existing engines and any possible replacement is much smaller. Also some of the newer designs derive efficiency from bleedless systems which would require much more than a re-engine to incorporate.

User currently offlinesrbmod From , joined Dec 1969, posts, RR:
Reply 5, posted (1 year 2 weeks 6 days 20 hours ago) and read 5445 times:

There have been very few successful re-enging programs for commercial aircraft over the years. The DC-8 one is the most successful of them. The 727 had a few various re-engine projects (One replacing the #1 and #3 engines with a newer version of the JT-8D engine used on them and another the replaced all three engines with RR Tays.) that were mainly used by cargo carriers to extend the life of their 727s once Stage III noise regulations went into effect. There were rumors of an MD-80 family re-engine project (Beyond the ability to upgrade the existing engine to a newer standard.) but the per plane cost estimates were not pretty not to mention the cost to develop the program as well as certification costs. Plus airlines like AA and DL really couldn't bear the possible costs due to the state of the industry about a decade ago. With the higher fuel prices in recent years, I bet airlines like Delta and AA wish that they would have been able to put newer engines on their MD-80 family a/c and the reduction in fuel costs as a result would have almost justified the costs of the work.

User currently offlineSpacepope From Vatican City, joined Dec 1999, 2914 posts, RR: 1
Reply 6, posted (1 year 2 weeks 6 days 20 hours ago) and read 5351 times:

Quoting srbmod (Reply 5):
With the higher fuel prices in recent years, I bet airlines like Delta and AA wish that they would have been able to put newer engines on their MD-80 family a/c and the reduction in fuel costs as a result would have almost justified the costs of the work.

I doubt this part. DL has said their MD-88s use about as much fuel on short hops as the A320. If the fleet is utilized efficiently, you pile the cycles on the -88 and send the A320s on longer routes where they can actually realize fuel savings, therefore avoiding the headache and extreme expense of a reengine project. As for the Mad Dogs now, it's much too late in the game to try it.



The last of the famous international playboys
User currently offlinesrbmod From , joined Dec 1969, posts, RR:
Reply 7, posted (1 year 2 weeks 6 days 17 hours ago) and read 5069 times:

Quoting Spacepope (Reply 6):
As for the Mad Dogs now, it's much too late in the game to try it.

The re-engining concepts that were being bandied about were about 8-10 years ago as a way to keep them around even longer. AA has already made their call in regards to the future of the MD-80 family of a/c while DL will be flying theirs for years to come as replacing it is lower on the priority list for them. Even G4 has set their MD-80 replacement plans in motion (Some folks thought that they'd pick up AA and DL a/c as they got retired....).


User currently offlineRevelation From United States of America, joined Feb 2005, 12426 posts, RR: 25
Reply 8, posted (1 year 2 weeks 6 days 13 hours ago) and read 4779 times:

Quoting B757forever (Reply 4):
What you say about the DC8 is correct because the huge leaps in technology and efficiency from the original engines to the CFMs more than paid the cost of modification.

As mentioned above, another issue is that noise regs would have forced the early retirement of frames that still had many cycles/hours left on them. Also at the time there wasn't really a wave of three or two engined a/c ready to replace the three and four holers with better economy and with two person crews so there was a better business case for keeping the older frames running.



Inspiration, move me brightly!
User currently offlineflyingclrs727 From United States of America, joined Apr 2007, 733 posts, RR: 0
Reply 9, posted (1 year 2 weeks 6 days 13 hours ago) and read 4712 times:

Wouldn't it make more sense to get a PIP for the existing engines? If RR put a new combustor on the RB-211's on 757's, wouldn't that improve the economics and range of transatlantic 757's?

User currently offlinebjorn14 From Norway, joined Feb 2010, 3412 posts, RR: 2
Reply 10, posted (1 year 1 week 2 days 4 hours ago) and read 3526 times:

If the plane has an 'engine upgrade' what's the recertification process for the whole frame?


"I want to know the voice of God the rest is just details" --A. Einstein
User currently offlineDalmd88 From United States of America, joined Jul 2000, 2540 posts, RR: 14
Reply 11, posted (1 year 1 week 2 days 2 hours ago) and read 3482 times:

Quoting flyingclrs727 (Reply 9):
Wouldn't it make more sense to get a PIP for the existing engines? If RR put a new combustor on the RB-211's on 757's, wouldn't that improve the economics and range of transatlantic 757's?

Engine performance for the 757 isn't what is driving their retirement. Airframe costs and cycle limits are the driver. The airframes are just getting old. The DC8 didn't have the lower cycle limits that newer generation aircraft have.


User currently offlinelightsaber From United States of America, joined Jan 2005, 12981 posts, RR: 100
Reply 12, posted (11 months 4 weeks 1 day 10 hours ago) and read 2621 times:
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New engines are expensive. Upgrading an engine requires an airframe be out of service for months due to the detailed structural work. Instead of a re-engine, we'll see winglets (maybe?) and other improvements extend the A330 sales life. But engines? Unlikely.

And the 777 was already re-engined. The current GE-90-115 is not the GE-90A. The 778/779 will have yet another engine.

Quoting flyingclrs727 (Reply 9):
f RR put a new combustor on the RB-211's on 757's, wouldn't that improve the economics and range of transatlantic 757's?

That would do nothing for fuel burn. Oh, a new combustor might have less pressure drop, but if 99.99% of the fuel isn't burned, the combustion engineers didn't do their job and Pratt's engineers did. There is little to no range from the combustor unless the turbine cooling pressure drop is also modified the same. Even then, you're talking 1/4% more range. Combustors are changed for cycle durability or emissions. Ok, I know of one for high altitude relight. Efficiency?    That is done by compressor, turbine, and fan efficiency.

What can be done with old engines is fan and compressor improvements. These improve fuel burn as well as improve durability. For the 757 Pratts, an extension to turbine life would help (say, new coatings), but it isn't enough to make the 757 economic.

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
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