tsl1011
Posts: 64
Joined: Thu Jan 01, 2004 9:11 am

Different Engines On The Same Type In A Fleet.

Tue Sep 27, 2005 2:11 pm

Hi everyone.

I was sitting at work today and letting my mind wander (it can be the only exercise I get...) when I started thinking about airlines that have different powerplants on one type of plane within their fleet. The catalyst was seeing one of the 747-400s Cathay Pacific recently aquired from Singapore Airlines (specifically, B-HKD) here at YVR a few weeks back. These planes have PW powerplants, in a 744 fleet which is otherwise all RR powered. Other examples that come to mind are British Airway's B772s (RR and GE), Air Canada's B763s (PW and GE, I think) and American Airlines' B752s (RR and PW). (I know the second two examples are mixed fleets due to one airline taking over another's planes, but the first two were by choice, so to speak.)
My question is, do the pilots in these airlines have to be seperately rated to fly each engine/aircraft combination? Do the various powerplants cause significant differences, for example, in takeoff speeds and performance for a given weight or even different MTOWs? Or are they pretty much the same from the pilots perspective? In my first example, would Cathay have had to hire new pilots to fly the PW 747s, or at least spend time and money retraining some of their current pilots, or is there just one rating for the 747-400?
I know that different engines means more spare parts need to be stocked and more training is needed for the maintainance crews, meaning added costs. I'm kind of curious how much it adds to the aircrew costs as well.

Tim
CYVR
 
Dougloid
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RE: Different Engines On The Same Type In A Fleet.

Tue Sep 27, 2005 10:59 pm

Hmmmmmmmm.....good question.

The only thing I ever worked on that had a similar situation was on some Beech Kingairs that had Garrett engines on them instead of the more typical UACL PT6....although the pilot requirements were no different the way the aircraft performed was entirely different.....the kind of operating envelope that you can use when an engine offers you "instant-on" performance instead of having to set up for the wind up so to speak made it an entirely different and better aircraft. Plus you had all the bleed air you could ever want with no drop in performance....

With the big ones the key would be the maintenance and parts stocking issues on the one hand, and what the ultimate performance of each type of engine would be on the other....
If you believe in coincidence, you haven't looked close enough-Joe Leaphorn
 
SlamClick
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RE: Different Engines On The Same Type In A Fleet.

Tue Sep 27, 2005 11:30 pm

I've never seen any intermix other than differing "dash numbers" which is not uncommon.
I've run a JT8-D-1 on one side and a -7 on the other, or a -7 and a -9 together. Usually it comes with operating limits on the more powerful engine.

Symmetrical intermix used to be common enough.

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ZB330
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RE: Different Engines On The Same Type In A Fleet.

Tue Sep 27, 2005 11:52 pm

Doesn't add to flight crew training costs. In my airline we fly the A320 powered by CFM's and the A321 powered by IAE's. All pilots do a base check (simulator check) twice a year. Each base check consists out of two days. So one day we "fly" with CFM's and the other day we 'fly' with IAE's. It is just different sofeware which is loaded in to the sim.
And the only reason we do this is because the CFM's have a N1 indication which you normally use while the IAE's have a EPR indication.

ZB330

By the way you requested was about different engines on the same type within the fleet. Out of pilots point of view you can see the A320/A321 as more or less the same type.

[Edited 2005-09-27 16:54:10]
 
Pihero
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RE: Different Engines On The Same Type In A Fleet.

Wed Sep 28, 2005 7:24 am

Quoting TSL1011 (Thread starter):
do the pilots in these airlines have to be seperately rated to fly each engine/aircraft combination?

Generally speaking, no.
Each pilot would be responsible for learning the differences from his flight manual.The first flight should be done with an instructor and that's about it.
In terms of performance, as each engine, for economical reasons has been closely taylored to the aircraft,it's quite transparent.
The worst I have personally seen was the mix of 747-100 cargo planes equipped with the venerable PW with a fleet of -200/300s powered by CF-6s. It was not fun going back to one's books to re-learn the operations of the JT-3 with water injection every three to six months. And I'm not even talking of the abominably poor performance of these PWs at max gross out of Mexico in the summer time !
Contrail designer
 
calpilot
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RE: Different Engines On The Same Type In A Fleet.

Wed Sep 28, 2005 7:31 am

UPS operates the B757 with mixed engines, P&W and RR's. You do not have different crews to fly the different sub-fleets.

Similar to operating different aircraft in the same sub-base, ie., the B767/B757 crew base at any of the airlines. It's no big deal.
 
CosmicCruiser
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RE: Different Engines On The Same Type In A Fleet.

Wed Sep 28, 2005 7:49 am

Fedex has GE and P&W powered MD-11s. The P&W use EPR and start slower.
 
Dougloid
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RE: Different Engines On The Same Type In A Fleet.

Wed Sep 28, 2005 10:37 pm

Quoting Pihero (Reply 4):
It was not fun going back to one's books to re-learn the operations of the JT-3

JT3C/D were used on the B707 and 720 plus KC135.
If you believe in coincidence, you haven't looked close enough-Joe Leaphorn
 
LMP737
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RE: Different Engines On The Same Type In A Fleet.

Thu Sep 29, 2005 12:42 am

Delta's 767's use both Pratt and GE motors.
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PPVRA
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RE: Different Engines On The Same Type In A Fleet.

Thu Sep 29, 2005 12:50 am

Varig has GE and RR B777s, and their MD-11s are GE and PWs (I think). The MD-11s are especially a bad case since each aircraft has two different engines by default, so that's a total of 4 different engines/training/spare parts.

Cheers
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jeffry747
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RE: Different Engines On The Same Type In A Fleet.

Thu Sep 29, 2005 4:13 am

Quoting CALPilot (Reply 5):
UPS operates the B757 with mixed engines, P&W and RR's.

N401UP-N435UP- PW2000s.
N436UP-N475UP- RR RB211s.
C'mon Big B, FLY!
 
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litz
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RE: Different Engines On The Same Type In A Fleet.

Thu Sep 29, 2005 4:35 am

Quoting LMP737 (Reply 8):
Delta's 767's use both Pratt and GE motors.

Which ones, on which planes (or models) ? Is there a list somewhere that shows this?

- litz
 
cloudy
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RE: Different Engines On The Same Type In A Fleet.

Sun Oct 02, 2005 11:57 am

Can anyone come up with examples that are not the result of a merger? The only thing I can think of is a few 777 operators may be forced to operate a mixed fleet for awhile because of the 777-300ER and 777-200LR use only GE engines.

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