Phone Wind,
The Angola situation is not to do with anything CHC has done. Sonair has over the years told the operator (Court in those days) to leave at least twice to my knowledge and after a year or so they had got back into the country.
This time it may be permanent, though because Sonair has got themselves geared up with modern equipment and are hiring the guys they will need to keep it going for them.
I had heard of rumours that one of the CHC ships had been extended past the deadline, but that is only rumour till proven. I also heard that BP had objected to Sonair appointing themselves as the operator of the BP contract and they had been told to "take it or leave it" by Sonair. Strictly rumours, though.