Just reread your post #20. Wow, I thought all C-box failures on CH-47s were fatal.
True story: I set foot in a Chinook for the first time in 2005 during Armed Forces wkd at Ft Rucker. The pilots invited me at age 56 to join their USAR unit & transition (last flew in 1986). Went to a flight surgeon & by golly I got my up slip.
Told their CO I was honored, but flying was a young man’s game. Retired in 2011 at 62.
As you know, the x-box or combining box in a hook, same as in a 46 (Frog) connects forward and rear rotor transmissions so the blades are always in synch.
I was carrying an external load in '69 out of LZ English, Master caution lit up, x-box temp way up, x-box oil pressure way down. Trouble!!
Punched off the external load and made a maximum effort descent. I focused on a dark green spot for some reason and when I flared, discovered it to be a canal overgrown with weeds.
I asked the flight engineer if we had 10 seconds to move it to the right. He is 40 feet back where the action was and he replied "Sir, put it down"
Remembering that the hook will float I put it into the water. I forgot the hatch to the cargo hook was still open and sure enough the CH-47 proceeded to sink right there.
We shut down and climbed on top and were soon rescued by a slick. A couple of days later, a CH-54 Skycrane came and drug it out of the canal where it drained water until it was light enough for the ride home.
Maintenance later told me one of the shafts in the X-box was crystallized, meaning it was red hot and ready to let go
So Yes, i survived a failure of the combining transmission failure by seconds.
All this to say "So what if the transmissions on the Osprey are linked, things can and will go south in a hurry!"