Not "out" as far as i'm aware lowmick, whilst the aircraft is a SPA aircraft, when operated on an AOC, it is required to operate as a multi-pilot operation, and therefore the 500 hours can be counted towards unfreezing the ATPL...and know of people who have unfrozen with the C525 hours counting towards the 500 hours total, obviously subject to getting a suitable Type to unfreeze on, and the skill test.