BestWestern
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Changing Engine Mfr On Delivered Aircraft Poss?

Fri Nov 18, 2005 6:47 pm

Engine choice for an airline can be nearly as important as the aircraft they choose. Now and again, airlines are left with aircraft because they chose the wrong engine manufacturer (BA and the 767 come to mind).

How much work is involved in retrofitting an aircraft to take different engine types, and has it been done?

(BTW I'm new to Tech_ops forum - go gently on me!!!)
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tepidhalibut
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RE: Changing Engine Mfr On Delivered Aircraft Poss?

Fri Nov 18, 2005 7:56 pm

Basically, it a BIG job. You'd need to consider the change of engine, a change of pylon, probably wiring in the wing and fuselage, and major change to the flight control system. And then you need to recertify the airframe.

Financially, you'll have to dump the old engine and hope you could find a buyer. However, you'd also need significant support (technical and paperwork-wise) from the airframer, who probably charge you and the full market price. (They're not going to sell any more airframes in the deal, so there's no incentive to discount.)

Has it happened before ? I can't think of any real examples. If it was worthwhile, I'd have expected the PW4000/B777's to be prime candidates.


NB : The BA / 767 example. From what I've been told, RR offered the RB211 on the 747, and BA liked it. The RB211 wasn't designed for the 767, but BA demanded it. BA got what they wanted for fleet commonality, and I'm not aware of any major problems with it. (However I bow to the knowledge of any passing BA powerplant people.)
 
gordonsmall
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RE: Changing Engine Mfr On Delivered Aircraft Poss?

Fri Nov 18, 2005 8:15 pm

Quoting TepidHalibut (Reply 1):
Has it happened before ? I can't think of any real examples. If it was worthwhile, I'd have expected the PW4000/B777's to be prime candidates.

Atlas Air contracted Boeing to retrofit a load of P&W powered 747 frieghters with GE CF6's a few years back.

IIRC they salvaged the pylons from some old 741's that were sitting in the desert.

As for the BA 767's with RB211's, the main problem is the huge increase in empty weight compared to the GE powered versions - I'm not sure the exact figure, but I believe the figure of 500kgs per engine was once mentioned in this forum.
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zeke
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RE: Changing Engine Mfr On Delivered Aircraft Poss?

Fri Nov 18, 2005 10:16 pm

I have seen CFM56 engines on DC8 and 707 freight aircraft.
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PhilSquares
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RE: Changing Engine Mfr On Delivered Aircraft Poss?

Fri Nov 18, 2005 10:46 pm

One of the advantages of the 787 is the ability to switch engines without a major rework of the aircraft. Leasing companies will be able to swap engines to meet customer's needs.

The Atlas deal wasn't "loads" and it wasn't old 100 pylons. It was a major rework of the entire aircraft. The one thing that made it somewhat "cost effective" was the AD on the pylons. In essence, because of the AD, Boeing subsidized some of the cost.
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HAWK21M
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RE: Changing Engine Mfr On Delivered Aircraft Poss?

Sat Nov 19, 2005 1:49 am

Quoting PhilSquares (Reply 4):
One of the advantages of the 787 is the ability to switch engines without a major rework of the aircraft. Leasing companies will be able to swap engines to meet customer's needs

Being Bleedless,there won't be many options.But a good start no doubt.
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timz
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RE: Changing Engine Mfr On Delivered Aircraft Poss?

Sat Nov 19, 2005 2:09 am

Didn't Cargolux put GE's on a couple of 747s?

And of course many smaller airliners have gotten new engines-- JT3Cs replaced by JT3Ds, and didn't a few JT4A DC-8s get JT3Ds? Those UPS 727s replaced JT8Ds with Tays, and all the DC-8-70s.
 
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lightsaber
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RE: Changing Engine Mfr On Delivered Aircraft Poss?

Sat Nov 19, 2005 2:29 am

Quoting BestWestern (Thread starter):

How much work is involved in retrofitting an aircraft to take different engine types, and has it been done?

TepidHalibut did an excellent description. Besides Parts, its almost $1million in certification costs per airframe. So engine changes aren't done lightly.

Quoting TepidHalibut (Reply 1):

NB : The BA / 767 example. From what I've been told, RR offered the RB211 on the 747, and BA liked it. The RB211 wasn't designed for the 767, but BA demanded it. BA got what they wanted for fleet commonality, and I'm not aware of any major problems with it. (However I bow to the knowledge of any passing BA powerplant people.)

BA has been happy with it, there just isn't any resale. But then again, the 762 market is very fragmented: CF-6 (Multiple versions too!), JT-9D, pw4000, and BA's RB211's.

Quoting Gordonsmall (Reply 2):

Atlas Air contracted Boeing to retrofit a load of P&W powered 747 frieghters with GE CF6's a few years back.

Woa! Keep in perspective, that was JT-9D's!

The Pw4000 are well liked by some airlines. The big problem on the 777 was the botched pw4098. Thus, the 773 with Pratt's is very underpowered and the 772ER is a little underpowered. Due to the intense amount of customization on the 777 for each engine, I just do not see any airline swapping.

Quoting PhilSquares (Reply 4):
One of the advantages of the 787 is the ability to switch engines without a major rework of the aircraft. Leasing companies will be able to swap engines to meet customer's needs.

 checkmark  Don't forget, Boeing made them go as far as sharing a nacelle!!! Oh, they won't be 100% identical at the end (in my opinion Boeing will allow variations to keep schedule). But it has been promised that swapping an engine type will be sub 2 hours! Lessors are going to love the 787. Expect to see more bleedless engine airframes in the future just because of this feature. (Imagine if the L1011 had been built with this feature. The RR strike wouldn't have hurt Lockheed much at all.)

Quoting Zeke (Reply 3):
I have seen CFM56 engines on DC8 and 707 freight aircraft.

The UA DC-8 engine refit is famous for several reasons: 1) launched the CFM-56, and 2) it was a profitable refit for all involved.

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