Some of the issues identified are going to present more problems – and indeed, in some areas the F-35 program office has given up and accepted lower performance. Sustained g and transonic (Mach 0.8 to 1.2) acceleration specifications have been relaxed for all three variants — indicative of less-than-expected specific excess power, most likely due to higher drag.
The F-35C’s transonic acceleration has changed dramatically, increasing by 43 sec. compared to a 65-sec. threshold requirement. Operationally, one impact of this change is on the time at supersonic speed available in any given mission profile: a long, full-power transonic acceleration burns a lot of fuel.
The F-35B has a full-page litany of mechanical problems with the powered-lift system, including a couple of issues – redesigning the driveshaft, and a new clutch material — which have large lifetime and maintainability impacts and for which solutions are still in the design stage. There are no showstoppers, but these issues do not point to a low-maintenance system in service.
All versions are still restricted in maximum Mach number at altitude because of exhaust heat damage to coatings and structures on the horizontal tail surfaces, a problem that surfaced in 2011.