C-17B

http://www.flightglobal.com/articles/2008/08/19/314814/boeing-offers-c-17b-as-piecemeal-upgrade.html

# Stronger Engines. No real surprise here, my estimation is about 50-55kN more for each engine. Question is, can this be done within the limits of the current nacelles. I think NO. A switch to a small PW4000, or even a GE CF6 would be required. Would also require a re-design of the wing because both engines are fatter, but shorter.

# New double-slotted flaps. Also requires a re-designed wing. And when we’re at it: More wing area wouldn’t hurt.

# An additional belly landing gear. That is a major structural upgrade. Actually I don’t think that is realistic. Opinions?

The rest is electronics. What I would see as useful (also in the interest of aerodynamics) is a slight stretch of the fuselage. Maybe 3 feet or so.

Everything but the belly landing gear could be re-fitted to existing A models (which could be brought up to a common build standard at last). A number of new B models, like 3 or 4 years of production, would be interesting to get rid of the older batches of A models. And then the priority should be a steady slow-rate programme, like 10 to 12 a year, for attrition replacement and to keep the average age of the fleet low-ish.