On a quick read, tuc, I think you have mis-interpreted Walter's post?
Walter - I can see no logical reason for anyone to 'hide' the fitment of what is/was a pretty standard concept in a helicopter. Radio homing devices have been around and used for decades. Whether this kit to which you refer was 'secret' or 'on special trial' I do not know. Likewise no logical reason to 'hide' the fact that it might have been fitted on this hull.
What you are suggesting is that the 'hiding' here would have been
a) The brief to 'test' it on this trip
b) The involvement of 'nefarious' personnel (your 'men in black') in this 'test'
Why not focus on that? What 'evidence' can you muster that the crew (who wanted a MK I?) were either tasked or briefed on such a 'test'. That would indeed be crucial to your case.