Placekicker From United States of America, joined Apr 2008, 22 posts, RR: 0 Posted (4 years 4 months 5 days 5 hours ago) and read 4720 times:
an aircraft's engines if it believes there could be an advantage to do so? Assume that Delta Airlines had a 767-300 which it purchased with P&W PW4000-94 engines. Say two to four years have elapsed and Delta wants to consider replacing the worn engines with one of the three other engines suited for the 767-300, namely the P&W JT9D-7R4, GE CF6-80A, or the GE CF6-80C2. Could this be done with minimal expense (outside of the cost of the replacement engines (which would have to be replaced after their lifecycle anyways)? Do airlines ever do this? Or is it once an airline purchases an aircraft with a specific type of engine, that it must replace the worn engines with new engines of the same model?
Kiwiandrew From New Zealand, joined Jun 2005, 8435 posts, RR: 14 Reply 1, posted (4 years 4 months 5 days 5 hours ago) and read 4683 times:
Interesting question Placekicker ,
I believe that it in general it is very difficult and costly to do so, ( with the exception of the 787 where apparently airlines will be able to change from RR to GE or vv - but even then I believe that the originally targeted change of less than a single day has now been deemed over optimistic ) while I do not know much about the technical side of things I believe that on aircraft where more than one engine type is offered the engine pylons and pylon mountings may differ between engine types , and interfaces such as bleed air systems presumably also differ , so it is not simply a matter of taking one engine type off and bolting another one on in its place . I am sure that some of the maintenance types who are on the site will be able to give you much more detailed info on this than I can
Moderation in all things ... including moderation ;-)
AA737-823 From United States of America, joined Mar 2000, 5386 posts, RR: 11 Reply 3, posted (4 years 4 months 5 days 5 hours ago) and read 4630 times:
It's possible, but very costly.
There are hardware issues- the connections for fuel, hydraulics, pneumatics, and sometimes even the physical motor mounts themselves, are in DIFFERENT places on different engines built for the same airplane.
This is very frustrating to amanufacturer and a leasing company, who can get stuck with an old 772A with Pratts (cough cough, Varig) and not be able to get rid of them. Hence, we've already seen a 772A scrapped. That's certainly not the only reason, but it's a part of it.
There are also software issues- the onboard FMC and such are configured for the engines that are on the wing. I don't really think this is THAT big a deal, because software is software.
Quoting Placekicker (Thread starter): Could this be done with minimal expense (outside of the cost of the replacement engines (which would have to be replaced after their lifecycle anyways)?
Quoting Placekicker (Thread starter): Or is it once an airline purchases an aircraft with a specific type of engine, that it must replace the worn engines with new engines of the same model?
You're making a bad assumption here, namely that engines are replaced after a relatively short (compared to reality) life cycle.
There are some ANCIENT jet engines out there. Once they reach their cycle or hours limits, they're inspected. One some models, like the RR RB211, many repairs and parts replacements can be done with the engine still "on-wing". Hence American Airlines has the on-wing record for that engine of 36,000 hours (as of two years ago when I heard about it, anyway... indirectly from AA mx). Other engines, like the familiar old JT-8D, typically require removal from the wing more often.
BUT- all that to say, engines last a LONG, LONG time... Decades, even.
Now, your proposal HAS been done in the past. If the airline is going to benefit from fuel burn or reliability improvements, the balance starts to tilt more toward "feasible." Hence so many DC-8-60 series aircraft became DC-8-70's, with the changeover to CFM-56 engines from their original Pratts.
Viscount724 From Switzerland, joined Oct 2006, 21690 posts, RR: 23 Reply 4, posted (4 years 4 months 5 days 5 hours ago) and read 4618 times:
Quoting Kiwiandrew (Reply 1): I believe that it in general it is very difficult and costly to do so,
I believe it is extremely rare apart from major conversion projects like the CFM56 conversion of 110 60-series DC-8s as mentioned above. However at least a couple of 747s were converted from their original P&W engines to GE. One of them below. Same aircraft in all photos.
Viscount724 From Switzerland, joined Oct 2006, 21690 posts, RR: 23 Reply 5, posted (4 years 4 months 5 days 3 hours ago) and read 4517 times:
The CFM56 conversion of the 60 series DC-8s reminds me of two earlier conversion projects in the 1960s involving the ConvairLiner series which had their original P&W R2800 piston engines replaced with turboprops.
170 Convair 340/440s were re-engined with Allison 501s, becoming Convair 580s, with major improvements in performance and about a 20% increase in gross weight as the Allisons are about 50% more powerful than the original P&Ws. Some structural changes were needed, mainly larger vertical and horizontal tail surfaces.
A less successful ConvairLiner conversion saw 38 Convair 240s and 27 Convair 340/440s re-engined with Rolls-Royce Darts, the 240s becoming Convair 600s and the 340/440s becoming 640s. (The Allison 501 was too powerful for the Convair 240 airframe so that project only involved the 340/440.)
AA777223 From United States of America, joined Feb 2006, 1116 posts, RR: 7 Reply 7, posted (4 years 4 months 4 days 19 hours ago) and read 4230 times:
If I remember correctly, the very first T7 was a 772A with Pratt engines. After testing was done, the original customer didnt' want it. It was then, after sitting on a Boeing lot somewhere for a very long time, finally sold to a chinese operator...I'm wanting to say China Southern. They would only accept the aircraft if Boeing, at their expense, switched the engines to GE90s. This supposedly was done "at great time and financial expense". I don't know if this aircraft was intended for UA or not. I can't find the photo or customer code on it, so I do not know for whom it was originally intended. Any information would be greatly appreciated.
BMI727 From United States of America, joined Feb 2009, 14419 posts, RR: 26 Reply 9, posted (4 years 4 months 4 days 18 hours ago) and read 4218 times:
It is costly and relatively rare, but possible.
Usually when engines are upgraded (like 5X 727-100s and DC-8-70s) the upgrade is usually part of a more comprehensive conversion. As far as changing from one type of engine to another comparable type, it is extremely rare. The 787 is designed to have a common interface, but I heard that there were problems it. I heard that it was mostly leasing companies pushing for this capability.
Why do Aerospace Engineering students have to turn things in on time?
AAMD11 From UK - Wales, joined Nov 2001, 1040 posts, RR: 1 Reply 10, posted (4 years 4 months 4 days 18 hours ago) and read 4174 times:
Quoting AA777223 (Reply 7): If I remember correctly, the very first T7 was a 772A with Pratt engines
WA001, the first 777 built was a 777-200. It was the principle test aircraft in the certification process. I don't think it was originally destined for any particular customer, but nonetheless when certification was complete, Boeing tried to get rid of it.
The aircraft did around 1,800 flying hours up until mid 1997 when testing was complete. They put the frame up for sale around that time and it found no buyers until CX came along in mid 2000 (around May or June). It appears it took around six months to finish modifying the aircraft for passenger service - installation of galleys, toilets and so on - and the plane was delivered to CX in December 2000, complete with RR Trent engines.
Airbuster From Netherlands, joined Mar 2007, 388 posts, RR: 1 Reply 11, posted (4 years 4 months 4 days 17 hours ago) and read 4144 times:
Not to forget that airlines make good deals for spares and overhaul/maintenance of the engines, more so, iirc there are also leasing contracts for engines.
I believe to have read somewhere that it takes the manufacturer about 15-20 years of leasing an engine before it begins to make a profit.
CF6PPE From United States of America, joined Mar 2006, 309 posts, RR: 0 Reply 12, posted (4 years 4 months 4 days 6 hours ago) and read 3991 times:
In the early 1960's, a number of B707-100, B720(A), and DC8-10 frames were converted to JT3D-1 powerplants from JT3C powerplants. In some instances the JT3C-7, -12 were converted to JT3D-MC-7, -12 via a Major Conversion (i.e., MC) kit. The resulting frames were then known as B707-100B, B720B, and DC8-50. There were some work done on the airframes to accommodate the upgraded powerplants.
Note: B707-200 and B707-300 and DC8-20/-30 frames delivered with JT4A powerplants weren't able to be converted.
KC-135 tankers (762 each) were delivered with J57Pxx powerplants; early on some were converted to use TF33P3 (JT3D) powerplants when the frames were converted to other than tanker uses (usually at Martin-Baltimore).
The remaining KC-135 tanker fleet was converted to either JT3D or CFM56 power. Details of the tanker powerplant conversions have been discussed many times in A-net forums.
The so called Valsan (Partners) conversion replaces the outboard (JT8D) powerplants on B727-200 frames with JT8D-200 powerplants. The Valsan conversion/modification is done via an FAA STC (Special Type Certificate) Approval.
There has been at least one B707-300 frame converted to CFM56 powerplants and one B707 frame has JT8D-200 powerplants fitted.
Hopefully, I haven't munged up the above thoughts too much... anyway...
AA777223 From United States of America, joined Feb 2006, 1116 posts, RR: 7 Reply 13, posted (4 years 4 months 3 days 19 hours ago) and read 3831 times:
Quoting AAMD11 (Reply 10): WA001, the first 777 built was a 777-200. It was the principle test aircraft in the certification process. I don't think it was originally destined for any particular customer, but nonetheless when certification was complete, Boeing tried to get rid of it.
Boeing doesn't build prototype aircraft like Airbus does. So, surely they had a customer in mind when they first built that frame. What is its customer code, and to whom does it correspond?
KELPkid From United States of America, joined Nov 2005, 5962 posts, RR: 4 Reply 15, posted (4 years 4 months 3 days 12 hours ago) and read 3698 times:
Quoting Viscount724 (Reply 5): A less successful ConvairLiner conversion saw 38 Convair 240s and 27 Convair 340/440s re-engined with Rolls-Royce Darts, the 240s becoming Convair 600s and the 340/440s becoming 640s. (The Allison 501 was too powerful for the Convair 240 airframe so that project only involved the 340/440.)
Hehehe, one day at LRU we had a suprise visit from a Convair 680 (it was a RR Dart conversion). Well, when they taxied up, I noticed that an engine was feathered. Apparently, they had an in-flight engine fire and had to pull the fire bottle. A second 680 from the same company (a US freight operator) with a replacement engine, and to rescue the stranded cargo that was on-board the first one. It spent about two weeks on the ground. I have never heard more noisy engines before or since.
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
Viscount724 From Switzerland, joined Oct 2006, 21690 posts, RR: 23 Reply 16, posted (4 years 4 months 3 days 10 hours ago) and read 3669 times:
Quoting AA777223 (Reply 13): Quoting AAMD11 (Reply 10):
WA001, the first 777 built was a 777-200. It was the principle test aircraft in the certification process. I don't think it was originally destined for any particular customer, but nonetheless when certification was complete, Boeing tried to get rid of it.
Boeing doesn't build prototype aircraft like Airbus does. So, surely they had a customer in mind when they first built that frame. What is its customer code, and to whom does it correspond
As far as I can tell, it had no customer code when it was built or during its years with Boeing. It was just a generic 777-200. When it was refurbished, re-engined and delivered to CX 6 years later it was assigned the CX customer code and became a 767-267.
The first 757-200 which was never delivered to a customer but has been used for various test programs (most recently for the F-22 fighter) is also just a generic 757-200 with no customer code.
As a sidenote, that aircraft made the 757's first flight 27 years ago tomorrow (or the day after tomorrow depending where you are) -- February 19,1982.
Tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80 Reply 17, posted (4 years 4 months 3 days 4 hours ago) and read 3615 times:
Quoting AA777223 (Reply 13): Boeing doesn't build prototype aircraft like Airbus does. So, surely they had a customer in mind when they first built that frame.
Boeing built "prototypes" for everything up to the 777. The 777 was the first one where the first airframe was basically production-standard, but I don't think they intended to deliver it to anyone at the time.
Derik737 From United States of America, joined Dec 2004, 331 posts, RR: 4 Reply 18, posted (4 years 3 months 2 weeks 2 days 7 hours ago) and read 3190 times:
Can't forget the UPS 727-100 Rolls Royce Tay Turbofan Conversion!
Viscount724 From Switzerland, joined Oct 2006, 21690 posts, RR: 23 Reply 19, posted (4 years 3 months 2 weeks 2 days 6 hours ago) and read 3177 times:
Quoting Tdscanuck (Reply 17): Boeing built "prototypes" for everything up to the 777. The 777 was the first one where the first airframe was basically production-standard, but I don't think they intended to deliver it to anyone at the time.
The first 727-100, line #1, which made the type's first flight in February 1963, was registered N7001U and was delivered to UA in October 1964 and spent almost 27 years with UA. So it must have been built to production standards.
Line #2 was also used in the flight test program but it stayed with Boeing. Many people think it was the first 727 since it was registered N72700 and both aircraft originally had the yellow and brown Boeing livery. But UA's N7001U was the first one built and the first to fly.
Tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80 Reply 20, posted (4 years 3 months 2 weeks 2 days 4 hours ago) and read 3140 times:
Quoting Viscount724 (Reply 19): The first 727-100, line #1, which made the type's first flight in February 1963, was registered N7001U and was delivered to UA in October 1964 and spent almost 27 years with UA. So it must have been built to production standards.
Not necessarily. Although I have no hard evidence one way or the other, there's no requirement that it have been built to the same production process as later airplanes (that's what I meant by "production standard"). As long as it could be issued an airworthiness certificate (which it obviously was), how it got that way is somewhat secondary.
Ex52tech From United States of America, joined Dec 2006, 559 posts, RR: 1 Reply 21, posted (4 years 3 months 2 weeks 1 day 11 hours ago) and read 3030 times:
On thing that I did not see in any postings was the need to re-certify the airplane with the new engine. All the paper work and cost to do that is another item that makes it undesirable.
Many of the airplanes are at a point in their life/cycle that it would not allow the carrier to even break even on the modification. That was exactly the situation with the NW DC10-40 fleet, they were offered the JT9-7R4 to replace the JT9-20/-20J, but decided against the idea due to the retirement plan at the time and cost to re-engine and re-certify. JAL went ahead and re-engined their -40s, and as it turned out NW ended up keeping it's -40 fleet until their retirement.
"Saddest thing I ever witnessed....an airplane being scrapped"
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