Wally Mk2,
With regard to your question about what happens if the engine nacelles can't be rotated to the upright position for hovering see below.
The V-22 Osprey combines the flight regimes of both helicopters and high-speed turboprop fixed wing aircraft. The need to make the Osprey crashworthy within this expansive flight envelope led to many unique features. The basic layout of a tiltrotor puts the large mass items such as engines and transmissions out away from the crew and cabin areas. In the event of a crash landing the occupants are not jeopardized by these items entering the occupied areas.
In the event of a crash landing the wing is designed to fail outboard of the wing/fuselage attachment. This "mass shedding" absorbs kinetic energy from the crash. Otherwise, this energy must be absorbed by the landing gear, structure or the occupants. In the nose of the aircraft is a very strong structure called the antiplow bulkhead. This reduces plowing, or "digging in" of the nose during a crash. The forward fuselage is designed to absorb crash forces of 4 g upward and 6 g rearward. The tricycle landing gear on the V-22 is designed to absorb a high sink rate of 24 feet per second (0.4 ft/min, 7.3 m/s)
The cockpit and cabin structure is designed to be 15 percent stronger than the wing's failure load. The overhead wing design also makes the occupied areas inherently stronger and safer in a roll-over or inverted impact. The occupied cabin area is designed to maintain 85 percent of its volume during a crash. The cockpit and cabin seats stroke vertically to absorb crash energy. Each seat has a restraint harness. The design of the cockpit has minimized the number of head strike hazards.
In the event the V-22 must land with it proprotors in the horizontal or cruise position, the occupants are protected from flying proprotor shards. The blades simply fray into individual strands that pose no harm to the occupants.
I particularly like the way they casually say that "The blades simply fray into individual strands". Bit hard to see if it really works in this video....
YouTube - V22 "Osprey" CRASH
Like this effort though!
YouTube - v22 osprey roll
CH.