John Halliwell wrote:

have been fixed. It's a very complex creature and Bell/Boeing are
determined to try to fix it (tilt-rotor being their pet technology)
rather than look at other alternatives which may have fewer built in
problems.

The problems can be traced back to the fact that its a compromise design
based
around the ships it'll be operating from primarily. The physical size limits
of the V22
are totally restricted by the flight deck and elevator clearance issues for
the wasp-class
LHDs. Rotor diameter was restricted by needing a minimum blade-tip clearance
of 12 feet
with the island and a 5 foot clearance between the edge of the deck and the
osprey's wheels.
The blade, wing and naccele folding procedure were limited by the elevator
size on the LHDs.
Bigger elevators would have meant more room for useful things like bigger
engines, 4 blade rotors
and a longer wingspan (all of which would have improved the type's
performance in both the
hover and more importantly, single-engine operation). The previous XV-15
program operated
so well for over a decade because it wasn't tooo much airframe for too
little installed power/rotor
lift.