That is something I do. Also, it's not just the acquisition but the in-service technical authority; we are working on that.
We are completing a very large program to extend them to 2020. It is in the billions of dollars. We have a very detailed plan to do structural reviews, structural repairs, but also a significant number of upgrades to communications and their sensors. That is happening to all 77 aircraft.
Our estimate of the cost to go from 2020 to 2025 is about $400 million. We're doing work to bring detail to that. It breaks out as follows. Roughly half of that is for spares and maintenance. Irrespective of the aircraft we have—and I assume we have a fighter, which I think is a forgone conclusion—we will spend that money, irrespective of what was in the order of battle.
We have set aside another $200 million, approximately. Our efforts today to do the structural work to 2020 have worked very efficiently. They've worked very well. In fact, they have not been as costly as anticipated. That's because we have a process in which we, literally, take the aircraft completely apart, inspect all of the airframe, all of the structure, and then repair it where needed. In a number of areas there's been less repair required.
Our plan is to continue to do that. We will do as many aircraft as required to 2025. I'm not sure, at this point, how many that will be. We have an annual cycle of revisits. That will be some of the capital piece that we do to life-extend the airframe.
Of that $400 million, we've set aside about 20%—and again, these are rough orders of magnitude—for anticipated upgrades. If all of our allies go to a different set of communications crypto, we would upgrade the aircraft accordingly. That is the intention.
Again, about half of that money will be spent no matter what. It's about $200 million for structure, and potentially other pieces.
From the perspective of extending the life of the aircraft, that's what we'll do. From the context of the operational effectiveness of the aircraft, again, that's something the air force would have to speak to.