I think a number of crashes over the years and dependability looking at the internet Osprey’s Readiness Struggles: 4 Out of 10 MV-22s Aren't Available for Combat — But Initiatives Are Underway to Improve the Unique Aircraft's Dependability - Seapower
I remember the political wheeling and dealing that was going on when they were being developed. It seems that the Dept of Defence and the Navy didn't want them after they evaluated the prototypes but the Congress and president pushed the project through anyway. Again recalling the stories of they day, the V-22 was touted as being less vulnerable to ground fire than helicopters because of it's speed. But the Navy (read Marines) realized that the speed increase over helicopters wasn't great enough to make a big difference. And they'd be sitting ducks when transitioning for landing. I like reading about WWII planes and equipment and modern stuff isn't my thing but these stories caught my attention because they show how loathsome politicians are. In the US it is a custom to have a military flyover during the final verses of the national anthem before major outdoor sporting events. If I'm around the house I try to put the TV on for it even if I'm not going to watch the game. I've never once seen Ospreys. I always figured it was because it would be embarrassing if some of the scheduled ones were grounded but don't know for sure. Everything else from Apaches, C-130s, F-22s etc. The best ones are the ones with B-52s and B-2s.