Capt Tercrue
Thanks. I spoke to some buddies with a lot of time on the Chook (CH47) and they'd not run into it in many hours on type. I can remember talking to some CH54 (Skycrane) types in SVN after they'd hooked out my busted bird and they said they were very fearful of VR because of their normal profiles. My interest dates from a personal encounter. But I can't see how an overlapping tandem-rotored helo could generate a consistent vortex, yet I admit that I'd not found anything academic that said yea or nay. But more importantly, it would seem that it has been overlooked as a potential pitfall for the tilt-rotor breed. The TP's at Pax River will probably have some exciting rides whilst coming to terms with it. I wish them luck.
Pants
If you look at the following URL's I think the answer will jump off the page.
Unfortunately they thought about engine failure but disregarded pitch-lock, VR (espec asymm) and transmission failure. Nacelle-tilt gear-box failure can be accommodated because the blades are composites and will simply break off (harmlessly and hopefully symmetrically) during any enforced "run-on" landing.
http://www.navair.navy.mil/V22/fltcntls.htm
http://www.navair.navy.mil/V22/propul.htm
http://www.navair.navy.mil/V22/convert.htm
