Could help him but some of his issues had nothing to do with his injuries like his OCD and he had already had head injuries while making Hells Angels. No XF-11 crash will probably slow but not stop his mental decline.
That being said a functional Howard Hughes in the late '40s and into the '50s will probably make a big impact on his company and the US aircraft industry.
Agreed, Hughes isn't going to be rid of all that ails him by simply avoiding the XF-11 crash.
Assuming that someone catches the oil leak that caused the XF-11 crash, and that Hughes' first flight is successful, I'd wager that the XF-11 makes a good run at the DoD contract for a reconnaissance aircraft. However it's complexity and cost probably cause it to lose the contract despite the crash.
Hughes' failure in the XF-11 program might lead him to push the development of the Spruce Goose a little harder in order to compensate. Perhaps in TTL we'll see more tests of the aircraft and get a much better idea of it's performance and carrying capacity. The Spruce Goose probably flies earlier in TTL with more pressure by Hughes, perhaps avoiding his Senate hearing of OTL.
Now despite the potentially impressive performance of the Spruce Goose, I don't see it being built for the US Military. The twin failures of the XF-11 and the Spruce Goose, might just be enough to send Hughes over the edge, then again, perhaps not. Perhaps Hughes sets his sights on something else, I could easily see him looking at Yeager's breaking of the sound barrier and attempting to design a supersonic bomber to put him back into the good graces of the US Government.
Starting a year earlier than the same program that produced the B-58 Hustler, the Hughes bomber could just well be adopted by the US Military (perhaps after competing with and beating other rival companies). Perhaps Hughes can focus his OCD on winning the competition.