Apparently, HQ 1 Gp kept a list of 'approved' LZs - I'm sure it would be mentioned - would anyone care to illuminate this? However, the speed of the ac at impact would preclude such an idea (too fast for approach/landing).... unless they had an engine problem. Of course, we don't know, either way.
BTW, Chinook experts tell me that the engine indications found by the AAIB only tell us that the engines had stopped and run down in the same way. In no way does this tell us what the engines were doing beforehand. Anyone who states that the engines were 'fully serviceable' is guessing.