|Quoting Tornado82 (Reply 6):|
7% difference between 2 engines on the same bird is a hell of a difference!!! Engine commonality amongst fleets is one thing, but with a 7% burn difference its surprising anybody could pass up the PW's if that's the case.
Unless the Pratt is a shop queen.
And note I pointed out it was only a 3% difference at entry into service (when many airlines commited to an engine) and since then RR
might have improved the fuel burn (post 2001). At $20 to $25/bbl for oil, the RR
was cheaper even with this great of a fuel burn difference. (Recall, a missed flight is DAMN expensive and the pw2037 missed a few!) The RB211 is using a core designed for 58k of thrust lopping along at ~38k. So its quite a bit heavier. (Note: they did modify the high turbine quite a bit to reduce the thermo hit.) One has to consider the times the airlines committed to their purchase decision.
Note: Recall the pw2037 was the world's first in service commercial engine with mono-crystal turbine blades*. That's a 2% to 3% drop in fuel burn on its own!
Just for a tidbit on the difference in reliability circa 1998, the RB211 on the 752 was getting ~ 12,500 to 15,000 cycles between overhauls (in other words, regularly hitting the engine cycle limit). The Pratt? About 3,750.
Ok, the pw2037 has improved since then, but its still only about half of the RR
numbers. Recall that those overhauls are a couple of million too...
Recall, 1 cycle=1 cold takeoff, but a hot/high takeoff might count for 3 or more cycles! (More is possible, but rare) Convieniently the FADAC does the math for you...
If the Pratt had been half reliable, it would have owned the 757 market. The pw2037 is the dog of the Pratt Stable and a good part of the reason airlines have gone to other engine vendors. Poor reliabilty costs. Pratt knows there is no longer any acceptible excuse for poor reliability. Will they be given a chance again? I'm hearing from people in the know there will be one last chance, possibly announced later this year.
Note I said possibly.
|Quoting ConcordeBoy (Reply 7):|
Something I'm not aware of (a possibility) or do you mean PW2037?
Umm... its the upthrust...
I don't know why I always give this engine an extra 1k of thrust... oops. pw2037 is correct (Hey, in my own defense its an engine I haven't worked on. ok? If I screwed up on the pw6022/6024, pw4062, 4168 (wanna be 4172), 4090, 4098, 8163, 8157, 8133, V2500 A7, A9, or A12 I would have no excusse. Whew! Yes, most of those are paper engines/changes and I'm still under NDA for the sonic cruiser. naa naa)
|Quoting United_fan (Reply 8):|
"If I want a lightbulb,I'll buy a GE,if I want a jet engine I'll buy a Pratt & Whitney"
Love the quote!
*yea, a few caviats there on the single crystal bit...