Helimutt,
Overall, once the value of the company drops below it's liabilities, the company is legally insolvent and will (should) end up in court with it's creditors.
As a US listed stock, they could be able to file for bankruptcy protection (either Ch 10 or 11 - I can never remember which) which gives them a chance to turn the business around while the creditors are kept at bay and a viable business can emerge.
Whether this is possible for CHC I don't know but it has been successfully used to turn around a few businesses in both aviation and the car industry.
The shareholders take a real bath though and the company usually ends up pruning a huge of it off.