I don't trust tiltrotors anyhow.  They are like skydiving -- even if the
pilot does everything right, they can still kill you Just Because.

If ANY flaw appears in the transmission or power control systems, the
aircraft will most likely crash.

In helio mode, the same differential thrust problem that you have in a
310 now becomes a differential LIFT issue, with a very long moment arm.

In airplane mode, the rotors are too large to allow it to land like a
plane, and even if you shut down the engines and dead-stick, you will
catch the blades long before your landing gear is anywhere near the
ground, and it will flip you over on your back before you have the time
to swear.

Autorotation is relatively ineffective, because there just isn't enough
rotor area.

Just because a technology is attainable doesn't mean that it's practical.

Keith W

The props may or may not flip you over. Depends on how they stop. Also carbon props tend
to shatter rather than bend. For our small PAV single tilt rotor we advocate large airbags for
the pilot and pax instead of chutes as they inflate faster.

http://www.rotaryeng.net/VTOL.html

For high altitude tilt rotor PAV problems a ballistic chute will work fine.

I think the new variable twist blades
Boeing is working on will enhance auto rotation. It will certainly mitigate the vortex ring
state. Variable twist blades will make the disc area more effective in helicopter mode.

Tilt rotors are the future as they solve a lot of current car traffic and airport access problems.

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I just read  my copy of SAE Aerospace Engineering and Manufacturing magazine and I see
where Lockheed Martin is also getting into tilt rotor aircraft.