V22 operational issues
The V22 ultimately suffers from the same basic problem that any VTOL aircraft with a turboshaft engine suffers from: Debris ingestion into the engine during landing or takeoff that results in erosion of the compressor airfoils. This is a serious problem with any turboshaft engined aircraft, whether fixed wing, tilt rotor, or rotary wing. The V22's Rolls AE1107C engines are lasting less than 100 hours in service, even with their modern IPS systems. These are 1000 hour MTBR engines that likely cost over 1.5 million dollars each.
Besides the engine life issues, there are also issues with other subsystems such as the electrical slip ring life in the rotor system.
The reason the V22 is attractive as a CSAR platform is due to its speed and range capability. But its primary drawback for CSAR is its high rotor downwash velocities.