As far as I remember reading, the PS-90A-76 (the variant mounted on the il(4)76 Is rated at 14.5 tons of takeoff thrust (but can be uprated to 16 tons if needed according to this website)
Well if they get the 60 ton payload capacity and improved flight range with a 14 ton class engine then a PD-14 should be fine... I have a book that describes the Il-76 and it mentions that normal cruise thrust is 2 tons thrust per engine so it really only uses power for takeoffs and for reverse thrust for landing on shorter runways... so if that is the case then a PD-14 would be fine.
The previous engines on the il-76, the D30KP had 12 tons of takeoff thrust instead.
Yes, you are quite right... just looked up my book and it mentions the 12 ton thrust of the Il-76 and the A-40 used together with booster engines.
Which means 14 ton thrust engines should improve performance and make takeoffs shorter without making it too overpowered and therefore fuel inefficient.
But the PS-90 will not be produced forever, in a few years they will look for a new one.
Just going on memory and that has recently proven wrong, but the first PS-90 engines had a lot of American components and might have been the 14 ton thrust models I was thinking of. It wasn't until they got to the PS-90A3 model that they replaced all the foreign parts from them and I think the thrust was 16 or 18 tons thrust on those versions... which might be useful for heavier aircraft but perhaps a bit over powered for an Il-476.
The PD-14 would be a much more suitable design for efficient operations.
Until they rump up production of PD14, PD14M, PD18R etc and those engine accumulate enough experience, there will be still production of these engines. PS90 are also used in the il96 and in the Tu204.
Probably they are also cheaper than the PD14, so even if the consumption is 15% higher it will be acceptable for military or government use.
One of the stumbling blocks for the PS-90s was their high initial costs... I think the 16 ton thrust model of the PS-90 was something like 6 million US dollars per engine, so while it was more fuel efficient than the original D30 engine... you would have to use it quite a bit before the 800K D-30 became worth replacing.
I seem to remember they developed an upgraded D-30 to meet noise and emission requirements and did improve fuel consumption but not to the level of the PS-90, but without increasing the price 5 fold too.
The thing was that it was the military that was paying for the new engines and they emission and noise controls don't apply to military aircraft, so for a civilian operator 24 million to replace 3.2 million dollars worth of engines is a serious thing... it will take a lot of use before the fuel savings make up the amount spent on new engines and spares of course.
Although, I do not expect terminal failures with the PD-14. Russia has an established jet engine
development and production capability.
A good design process and making a family of designs based on the same model should reduce risk and make the process much more efficient and hopefully trouble free.
Maybe around 2028 or around that date... but at that point maybe they could be thinking about replacing the il76.
If they put the Il-276 into service and get an Il-106 into service then I really don't see any need to replace the Il-476 for a few decades... as a 60 ton payload capacity aircraft it fills a gap well. Perhaps a stretched version with PD-18 engines or something to still carry 60 tons but carry it much further perhaps...