Originally Posted by
Tech Guy
Out of interest, how many engine sales would be needed to make the R&D viable?
Could the upgraded engine be used in other aircraft to provide additional sales?
The R&D costs are highly variable depending on the nature of the changes. but engine changes don't come cheap. What typically happens is the engine company finds something and implements it into their newest engine design. Assuming it works out (they don't always), they may look at using it in an older engine design. Sometimes that works great and they get a significant improvement in fuel burn and/or EGT margin (which basically means time on wing) on the older engine design. Sometimes, it fails miserably (often for reasons that they never fully understand). Example - ~20 years ago GE implemented a new compressor design ('3d aero) on the GE90 - and it worked great with a big improvements in fuel burn and a corresponding drop in EGT. So GE tried to implement the same technology on the CF6-80C2 compressor - but the results were so disappointing on the CF6 that I don't think they even bothered to certify the change.
As far as being able to use the updated engine on other aircraft, there are two problems with that. First off, both the GP7000 and the Trent 900 were pretty much point designs for the A380 and are not really optimum for any of the big twins. Second, the engine designs are relatively old - the 737 (MAX), 747 (-8), 777 (X), 787, A320 (NEO), A330 (NEO), and A350 already have newer, more efficient engines available. In fact, of the currently produced large commercial airliners, the only one with engines older than the A380 is the 767 - and both the GP and Trent are too big to be suitable for the 767.