Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Difference Between AA's RR & UA/DL's P&W 757's  
User currently offlineVH-BZF From Australia, joined Oct 1999, 840 posts, RR: 0
Posted (14 years 5 months 2 weeks 4 days 19 hours ago) and read 2433 times:

I was interested to know the major difference bewteen the two power plants on the B757. Obviously they are made by two different manufacturers, but one would have thought that they both would produce the same amount of thrust! Was it price or performance in the end that persuaded AA to choose Rolls engines over Pratts (as I think the only other aircraft in their fleet with RR engines at the time was the F100?), as they have P&W's on their B727's & MD80's (albeit not high by pass engines) & GE on the rest of their fleet.
I also noticed that it took longer for AA to get FAA approval to fly their RR powered B757's to/from Hawaii than it did for UA & DL to fly their P&W B757's over the same route!

So whats the answer, any idea?

Cheers  


Ansett Australia - (was) One of the worlds great airlines!
19 replies: All unread, jump to last
 
User currently offlineRichie From Switzerland, joined Dec 1999, 143 posts, RR: 0
Reply 1, posted (14 years 5 months 2 weeks 4 days 18 hours ago) and read 2224 times:

Bluntly said, it could very well have been the fact that RR is no US based manufacturer.... But more probable is, that you need a certain amount of hours on the engines to prove the engine reliability, and as UA and DL combined get to that target quicker, they also got approval quicker. For ETOPS experts: as I know, you have to submit both total fleet hours of the airframe-engine combination, as well as your average per aircraft over a specific time.

RR engines (with exception to the first Generation of fans) are better ageing. Their fuel bias usually stabilises quicker and at higher level. Also it seems to be, that the design with LP, MP and HP turbine is less prone to wear and tear, therefore improving the on-wing time.

The whole engine game has become a rather philosophical battle between the experts, and there are enough pros and cons for each engine type to never come to an end.


User currently offlineKALB From United States of America, joined Mar 2000, 573 posts, RR: 0
Reply 2, posted (14 years 5 months 2 weeks 4 days 17 hours ago) and read 2191 times:

I believe AA's 777-200s are powered by the RR Trents.

User currently offlineVH-BZF From Australia, joined Oct 1999, 840 posts, RR: 0
Reply 3, posted (14 years 5 months 2 weeks 4 days 7 hours ago) and read 2169 times:

Thanks for your reply Richie & I think you are right about on wing performance! The less time the engine requires in the overhaul shop the better it is for the airline, also less wear & tear is usually a good sign too! Ansett recently (about 2 years ago) set a world record by having the longest (highest) time CFM56 engines aboard one of their B737-300's, apparently the engines had spent their entire life (about 8 or 9 years??) on the same airframe without having to be removed for overhaul. Whilst we are speaking about engines, did you know that a group of Australian Airlines engineers who worked on the B737-300 engines came up with the idea of flattening the cone on the front of the CFM56 engine, so that the engine wouldn't stall in heavy rain whilst the aircraft was taxiing! Prior to this all the engines had those sharp pointed cones!

Cheers



Ansett Australia - (was) One of the worlds great airlines!
User currently offlineFlyAA757 From United States of America, joined Jun 1999, 1013 posts, RR: 0
Reply 4, posted (14 years 5 months 2 weeks 4 days 1 hour ago) and read 2138 times:

Your comment about engine shape of the CFM56 on 737s is completely incorrect. I dont know who told you that, but they were playing a joke on you. The CFM56 is as it is for clearance and performance reasons.

User currently offlineRick From United States of America, joined Dec 1999, 129 posts, RR: 0
Reply 5, posted (14 years 5 months 2 weeks 3 days 18 hours ago) and read 2131 times:

I had read in a post some weeks ago that the PW 2000 engines had bleed problems. The writer never explained what he ment by that. Can any one elaborate on that statement? Is that related to the swooshing noise they make after the plane lands at the very end of the rollout?

User currently offlineVH-BZF From Australia, joined Oct 1999, 840 posts, RR: 0
Reply 6, posted (14 years 5 months 2 weeks 3 days 18 hours ago) and read 2122 times:

Sorry, AA757, I am talking about the cone/dome on the front fan, not the shape of the engine itself! I have been told by many B737 pilots that for some reason prior to installing the flattened cone/dome that in very heavy rain, the CFM56 engine was prone to stalling! Now I know that the similar CFM56 engine on the A320 still has the pointed cone/dome attached to the front (initial) fan, so maybe on the B737 it is a performance issue?????? Or the engine being alot lower to the ground is more prone to failure, who knows? Anyway my previous post was the story that was going around down under, true or not?

Cheers!



Ansett Australia - (was) One of the worlds great airlines!
User currently offlineAAR90 From United States of America, joined Jan 2000, 3475 posts, RR: 46
Reply 7, posted (14 years 5 months 2 weeks 3 days 17 hours ago) and read 2120 times:

>I believe AA's 777-200s are powered by the RR Trents.

RB211-535-E4B. I've never seen them called a Trent.



*NO CARRIER* -- A Naval Aviator's worst nightmare!
User currently offlineFlyAA757 From United States of America, joined Jun 1999, 1013 posts, RR: 0
Reply 8, posted (14 years 5 months 2 weeks 3 days 14 hours ago) and read 2102 times:

-BZF, Now I see what you're saying. Thanks for the clarification.

-AAR90, I think you seem to be one of the most knowledgeable people on this forum, so I'm sure that you misread this. The 757s are indeed powered by the -535E4-B, but he was referring to the 777, which are powered by Trents, a scaled up, and I believe re-fanned version of the RB211.


User currently offlineAAR90 From United States of America, joined Jan 2000, 3475 posts, RR: 46
Reply 9, posted (14 years 5 months 2 weeks 3 days 7 hours ago) and read 2101 times:

>-AAR90, I think you seem to be one of the most
>knowledgeable people on this forum,

I doubt that.  

>...so I'm sure that you misread this.

Uhhh, yep. Subject matter was 757's and I guess I wasn't awake yet during (failed) first reading. Sorry.

>The 757s are indeed powered by the -535E4-B, but
>he was referring to the 777, which are powered by
>Trents, a scaled up, and I believe re-fanned version
>of the RB211.

Not sure, but the original Trent was to be a modification (scaled up version) of the -211. Didn't follow its development so beyond that I'm a total novice.  





*NO CARRIER* -- A Naval Aviator's worst nightmare!
User currently offlineFLY DC JETS From United States of America, joined Feb 2000, 199 posts, RR: 0
Reply 10, posted (14 years 5 months 2 weeks 3 days 4 hours ago) and read 2123 times:

Somebody asked why AA chose RR over PW, here's history as I recall.

In the early '80s American Airlines ordered a large number of PW2000 engines without ordering airframes. (this was 1981,'82, or ,83) However, before they placed their order for aircraft they cancelled their order for PW2000s due to some early teething problems with the engine and PW's lack of quickness in dealing with the problem and [other] customer's needs. Either way, PW fell out of favor and AA got a deal that was real sweet for the RB211's along with the Tay's for their F100s.

Pratt and Whitney has fallen out of favor with a lot of airlines. In general, the company is very arrogant in dealing with customers. They tend to overvalue their importance and their position. As a result, they didn't come out with new products as needed, they are constantly late with deliveries, and they are slow to fix problems that occur. Several Airlines used to be strong Pratt and Whitney customers, including AA, however, most have long lost their alliegiance to PW. Here's a short list
American Airlines
Japan Airlines
Delta
Northwest- to a certain extent CFM's over IAE's.
SAS
Finnair
Singapore
Virtually all European Airlines



User currently offlineVH-BZF From Australia, joined Oct 1999, 840 posts, RR: 0
Reply 11, posted (14 years 5 months 2 weeks 3 days 2 hours ago) and read 2101 times:

Thanks for the info! Ahh yes it is very interesting how bad customer service, in this case P & W, can affect sales! I think performance has a great deal to do with it as well, AA are obviously happy with the RR engine on the B757 & their relationship with RR (hence the order for the Trent on the 777's!).

I believe that RR power the majority of the worlds B757 fleets & currently it is the only power plant ordered for the B757-300.
Speaking of reliability, RR have been making very reliable engines for a long time now, bar the gearbox problem on the Cathay A330's a few years ago, and are now the most preferred engine on the B777. This will of course change a little when Boeing start delivering the B777X series of jets with the exclusive GE90X engine on board & many airlines like AA, SQ & MH are none to happy about it either!

Thanks again!

Cheers  



Ansett Australia - (was) One of the worlds great airlines!
User currently offlineFLY DC JETS From United States of America, joined Feb 2000, 199 posts, RR: 0
Reply 12, posted (14 years 5 months 2 weeks 2 days 20 hours ago) and read 2079 times:

You are correct about the performance, they are definetly pleased, and they should be. I went back and looked through some info and found out that much of the AA PW2000 deal centered around PW's claim that the PW2000 would be 7% more fuel efficient. When the testing was performed and all was said and done, the 2000 was only a few percentage points better, but it was far less reliable early on, thereby negating the fuel savings. Either PW had to pay American Airlines something like $40 million dollars, or they lost the deal. They lost the deal, down the road, RR came knocking with a sweet deal for RB211's and Tays. The rest, shall we say, is history.

Have a nice day to all!


User currently offlineBuzz From United States of America, joined Nov 1999, 697 posts, RR: 21
Reply 13, posted (14 years 5 months 2 weeks 2 days 16 hours ago) and read 2096 times:

Hi VH-BZF, Buzz here. THat "swooshing" sound? It's the 14th stage air bleed that dumps air to prevent compressor stalls (think of a hot belch). it's open during engine start, when in reverse, and under some engine deceleration modes. At work we generally call it a "beanpot" valve, shaped like an old fashioned pot.

I also recall changing the CFM-56 spinners many years ago, It's supposed to provide no place for ice to build up on the tip. The A320 has a rubber end on it's spinner to keep the ice from adhering very long. I guess they both work after a fashion.

P+W vs RR engines: Well, customer support has something to do with it. Also delivery times (can they build enough engines to keep pace?), engine efficiecny has some bearing on it (although a 3 spool engine has more parts to buy). But i think -- suspect, but have no proof-- that it also comes down to who's willing to make a sale on a large block of engines.

Oh yes, the P+W 2000 air bleed problems: At the moment there are some random faults in the 2.5 bleed bellcranks, generally on high time engines. And there's no good way to get in to replace it without a teardown. But that's an efficiency issue.

We've also had bleed problems of a different sort on the line: engines won't provide bleed air after engine start. Funny, they were working when it came in..... We made a kit of hoses and valves and hook up to the bleed valves of the engine, cycle the bleed valves through without running the engine, replace failing valves. It takes about 3 hours on a slow night per engine. After getting through all 98 of our 757's and getting the kinks worked out, it's now done at C-checks.

OK, how did i get such opinions? I spend my nights fixing airplanes and teaching other mechanics at the Dreaded United Air Lines. Remember: if you don' t like school, don't play with airplanes. We go to school a lot, Mechanic, or Pilot.
g'day
Buzz Fuselsausage: Line Mechanic by night, DC-3 Crew Chief by choice.


User currently offlineVH-BZF From Australia, joined Oct 1999, 840 posts, RR: 0
Reply 14, posted (14 years 5 months 2 weeks 2 days 10 hours ago) and read 2057 times:

Thanks muchly for the info Buzz! Great to get quality info from people who actually work in the field! Hey UA wouldn't be a bad place to work, surely?

Regards



Ansett Australia - (was) One of the worlds great airlines!
User currently offlinePaddy767 From , joined Dec 1969, posts, RR:
Reply 15, posted (14 years 5 months 2 weeks 5 hours ago) and read 2022 times:

Didn't read the whole thread, but I fly both A/C. Operationally, they are about the same, with some minor differences. On start, the PW takes forever to spool up, more like a CFM56 and the triple spool RR gets going much quicker, like the low bypass JT's. everthing else is about the same, except on landing when you deploy the thrust reversers. The pratts stop you NOW, where the RR's seem to puff a little and then give up.

User currently offlineCV880 From United States of America, joined Mar 2007, 1134 posts, RR: 2
Reply 16, posted (14 years 5 months 4 days 14 hours ago) and read 1972 times:


I remember how amazing it was to see RR back in the AA fleet (they once had Speys on the 1-11s). Anyhow, I remember something about a condition that the AA 757s had to do MEX -ORD nonstop with a full payload. I believe that RR really bumped up the RB211 a notch to meet this guarantee. For all I know, Pratt promised the same performance, but I can't recall. Come to think of it weren't the AA757s the first to have the wide-chord fan blades? I think this was part of that MEX performance package.

I remember the PW2000 having problems early on, most of which Delta had to bear the brunt of.


User currently offlineAirlinenut From United States of America, joined Mar 2011, 3 posts, RR: 0
Reply 17, posted (14 years 5 months 3 days 10 hours ago) and read 1944 times:

From what I have read, the P+W 2037 that are used on the Delta fleet are not ETOPS approved. Instead they should have chosen Rolls Royce powerplants.

User currently offlineFLY DC JETS From United States of America, joined Feb 2000, 199 posts, RR: 0
Reply 18, posted (14 years 5 months 3 days 7 hours ago) and read 1945 times:

They are approved, however the airlines can choose to or NOT to maintain them in a fashion that will allow for etops approval.
Either way the PW2000 has ETOPS approval, at the current stage of the game, the PW is equal to the RR.

Delta choosing RR is your opinon, I happen to think it's false.


User currently offlineJet Setter From , joined Dec 1969, posts, RR:
Reply 19, posted (14 years 5 months 2 days 5 hours ago) and read 1943 times:

Every RB211-535E4 engine on the 757 has wide-chord fan blades, only the 535C which poweres some Air Europa/British Airways does not have wide-chord blades.

To meet AA's needs, RR made a derivitave of the engine, the RB211-545E4B, which has also been chosen by Continental, plus it is the sole powerplant for the 757-300. It provides around 3000lb of thrust more per engine than the standard E4

Regards
J E T S E T T E R


Top Of Page
Forum Index

Reply To This Topic Difference Between AA's RR & UA/DL's P&W 757's
Username:
No username? Sign up now!
Password: 


Forgot Password? Be reminded.
Remember me on this computer (uses cookies)
  • Tech/Ops related posts only!
  • Not Tech/Ops related? Use the other forums
  • No adverts of any kind. This includes web pages.
  • No hostile language or criticizing of others.
  • Do not post copyright protected material.
  • Use relevant and describing topics.
  • Check if your post already been discussed.
  • Check your spelling!
  • DETAILED RULES
Add Images Add SmiliesPosting Help

Please check your spelling (press "Check Spelling" above)


Similar topics:More similar topics...
Difference Between Flying Wing & Lifting Body? posted Wed Dec 28 2005 22:02:05 by Lehpron
Difference Between Propellor & Electric Hand Fan? posted Thu Jul 8 2004 07:30:30 by Ps76
Difference Between 767-300 & 767-300ER posted Mon Jun 5 2000 16:14:33 by Aa777dr
Difference Between 757 And 757-200 posted Thu Mar 7 2002 00:27:02 by H. Simpson
Difference Between A DC-8-71 And A -73 posted Tue Jul 25 2006 02:23:39 by Jeffry747
The Difference Between Flying And Surfing? posted Wed Sep 14 2005 02:58:18 by Ps76
Difference Between 747-200 Cockpit And 747-300? posted Tue Aug 16 2005 08:04:07 by Mozart
Difference Between A-Check, B-check, Etc.? posted Tue May 24 2005 08:29:30 by ORDSPOTTER
Difference Between Part 61 And Part 141. posted Tue May 3 2005 05:28:21 by Swimpilot
Difference Between Flaps And Slats? posted Fri Apr 1 2005 17:36:42 by JAM747

Sponsor Message:
Printer friendly format