TimT From United States of America, joined Jun 2001, 168 posts, RR: 0 Reply 6, posted (11 years 11 months 2 weeks 1 day 20 hours ago) and read 6870 times:
CFM's are way too cool-- on our 319-320 fleet the manual specs 2 (two) different CFM's. Got on and need the other? Change the FADEC! There you go. Might be able to do that on the IAE too. Just don't have any experience with them.
HAWK21M From India, joined Jan 2001, 31201 posts, RR: 58 Reply 8, posted (7 years 3 months 1 week 3 days 14 hours ago) and read 6765 times:
Recently most A320 operators are changing over from V2500 equipped A320s to CFM56B operated A320s.
Is there a Technical reason for that choice or purely Marketing.
The query is because for so many years the A320s out here were choosing V2500s until a few months back.
A/c train From United Kingdom, joined Jun 2001, 501 posts, RR: 4 Reply 9, posted (7 years 3 months 1 week 3 days 10 hours ago) and read 6720 times:
from a maintenance point of view, most jobs on the V2500 are simpler than the CFM-56, there are some really crap borescope plug locations on the CFM !!! Fan arrangements etc are simpler on V25.
Spares/ engine spares, I second VC-10, it seems harder to source a V2500 than a CFM, must be a maintrol nightmare if your airline doesnt hold any serviceable spare V25's.
As far as reliability, each airline will look at that question with their own view, I havnt heard of too many AOG's involving CFM engines.
Tristarsteve From Sweden, joined Nov 2005, 3689 posts, RR: 34 Reply 10, posted (7 years 3 months 1 week 3 days 9 hours ago) and read 6694 times:
We get both here. I work on a line station and in 18 years of CFM and 5 years of IAE, I have changed a starter on an IAE, and err thats it. We get about 4 a day. IAE advantage is that it doesn't use oil. I average 2 lts/day on CFM and 1 lt/week on IAE.
Laxintl From United States of America, joined May 2000, 22023 posts, RR: 51 Reply 11, posted (7 years 3 months 1 week 3 days 8 hours ago) and read 6687 times:
Having done the analysis on this specific subject previously I'd say the following.
The V2500 is a newer design, has a slight fuel burn advantage, and tends to degrade at a slower rate in EGT margins and consumption bias then the CFM56.
However both engines are very competitive and have gone thru several upgrades over the years, with CFM working on their latest "CFM56 Tech" package due out in 2007 which is to further reduce emissions along with a small fuel consumption improvement.
Due to the very competitive nature of the engines, operators often simply choose based on price or fleet commonality.
In my opinion, one cant loose with either choice, however I'd give the V2500 an ever so slight advantage.
From the desert to the sea, to all of Southern California
A319XFW From , joined Dec 1969, posts, RR: Reply 12, posted (7 years 3 months 1 week 3 days 7 hours ago) and read 6665 times:
Quoting Crosswind (Reply 4): CFMI concede in advertisements that the IAE V2500 has lower fuel consumption, but that the CFM56 has lower maintenance costs.
Make of that what you want...
An engine specialist at XFW that I spoke to was also of this opinion. That is why IAE are trying to make the V25000 more maintenance friendly and reduce the mx costs.
Quoting A/c train (Reply 9): from a maintenance point of view, most jobs on the V2500 are simpler than the CFM-56, there are some really crap borescope plug locations on the CFM !!! Fan arrangements etc are simpler on V25.
From talking to an AC mech, he said that they prefered doing maintenace on the CFM (compared to the IAE on the jetBlue a/c they did). This might of course be that they were used to the CFM from years on the the AC fleet. Also the thrust reverse mechanism on the CFM is simpler than on the IAE.
(A320tech - before you say anything, go blame Dale!)
The CFM56-7 (which is what I was referring to) on the next generation 737 has 24 wide chord blades just like the V2500. I wouldn't compare a CFM56-3 engine with 36 blades to the V2500. They're two different generations of powerplant. The only fair comparison of the V2500 to a CFM56 is to the -7 series.
320tech From Turks and Caicos Islands, joined May 2004, 487 posts, RR: 5 Reply 18, posted (7 years 3 months 1 week 1 day 21 hours ago) and read 6376 times:
(A320tech - before you say anything, go blame Dale!)
Hey, I haven't even said anything yet.
My impression, based on limited V2500 experience and lots of CFM, is that CFM's are easier to maintain. I have heard from others that V2500's are cheaper to buy. It seems likely to me that the difference is not significant enough to make a real difference, and so the deciding factor will be (as mentioned) fleet commonality and similar factors.
My airline seems happy with the CFM's, jetBlue seems happy with the V2500's.
In short, beats me.
The primary function of the design engineer is to make things difficult for the manufacturer and impossible for the AME.
Molykote From United States of America, joined Aug 2005, 1336 posts, RR: 30 Reply 19, posted (7 years 3 months 1 week 1 day 14 hours ago) and read 6337 times:
Quoting TimT (Reply 6): CFM's are way too cool-- on our 319-320 fleet the manual specs 2 (two) different CFM's. Got on and need the other? Change the FADEC! There you go. Might be able to do that on the IAE too. Just don't have any experience with them.
The two 'different' CFM56-5B engines for the A320 family include a "/P" series and a series not designated with the "/P" suffix. I believe the /P suffix indicates that some of the high pressure rotors employ a more efficient "3-D" (misnomer) airfoil section that non-/P engines lack. This is an actual hardware difference on the rotors and is of course independent of the FADEC installed. If you are familiar with the AMM (and it looks like you might be) the /P engine sometimes has different serviceable limits than the non-P counterpart.
- Each engine serial number has an "N1 modifier" associated with it. This N1 modifier is a measure of how a given engine performed in a test cell. When engines are moved between aircraft and may require a different thrust installation this N1 modifier is used in calculations to uprate or derate a given engine at an appropriate level.
- The thrust level of an engine is changed (perhaps more accurately "programmed") by installing a "data plug" that screws onto the ECU and conveys program information that sets the engine thrust output to the level desired by the operator. A given spare engine may have multiple data plugs tailored to its specific engine serial number and kept on standby for a later date if/when a change in thrust or new installation is desired for the engine.
- Each engine has an Engine Data Plate
This data plate is required for flight per FAR. Following a thrust level change as per above or the running of an engine in a test cell at any time the observed N1 modifier status and current thrust configuration are stamped onto the data plate.
Aside from the /P and non-/P difference between CFM56-5Bs, the only hardware difference (if you don't count the programmed thrust plug) is an additional sense line installed on the A319 (CFM56-5B6 or -5B6/P). This sense line is not installed on the A320 (CFM56-5B4) or A321 (CFM56-5B3) variants of the engine.
As far as hardware similarity is concerned (within a /P or non-/P family), the A320 and A321 have the same engine with exception of different thrust plug programming. The A319 configuration has an extra sense line installed. Both configurations can be achieved from the same engine serial number with no more than a couple hours of work to remove or install the sense line depending on which way you wish to go. No change (apart from screwing in a different thrust plug) is necessary to go A320<-->A321
Quoting Dl757md (Reply 13): Quoting A/c train (Reply 9):
Fan arrangements etc are simpler on V25.
I've done many fan blade lubes on both engines. The V2500 may have a slightly simpler fan design but the removal and installation on the CFM56-7 is far easier and quicker.
CFM56-5B is the relevant model if we are talking about an apples-apples narrowbus comparison.
Quoting Dl757md (Reply 16): The CFM56-7 (which is what I was referring to) on the next generation 737 has 24 wide chord blades just like the V2500. I wouldn't compare a CFM56-3 engine with 36 blades to the V2500. They're two different generations of powerplant. The only fair comparison of the V2500 to a CFM56 is to the -7 series.
In my opinion the only fair comparison is the -5B to the V2500. The V2500 is not available for comparison to a -7 due to the fact that the engines can't be installed on a common airframe for evaluation. I do understand where you are going with the similar appearance of the -7 and V2500 blades but no market competition exists between the -7 and V2500.
A319XFW From , joined Dec 1969, posts, RR: Reply 20, posted (7 years 3 months 1 week 1 day 13 hours ago) and read 6328 times:
Quoting 320tech (Reply 18): (A320tech - before you say anything, go blame Dale!)
Hey, I haven't even said anything yet.
It was my pre-emptive strike refering to what I remembered hearing in YWG!
I was wondering - what kind of effect does the non-circular inlet have on the 737 CFM's due to the lower landing gear?
Surely you have some performance reduction compared to the fully circular ones, as the air flow will be disturbed by it?
Scarebus03 From Ireland, joined Apr 2005, 291 posts, RR: 2 Reply 23, posted (7 years 3 months 1 week 4 hours ago) and read 6170 times:
Having a considerable amount of experience maintaining both types of engines my runaway favourite is the CFM56-5. I still have nightmares about the early V2500-A1s they were real heartbreakers. The A5 series is a much better engine than the A1 but I have had much more in-service V2500s fail borescope inspections than CFMs. The V2500 is quieter, uses less fuel, has way lower oil consumption and has better acceleration than the CFM. The CFM is easier to work on, has better on wing time between overhauls but is more expensive to choose as an option for the A32F (or used to be anyway). I can't wait to see a new V2500!