Let me clarify that ...... Class B aircraft do not require an SOM approved under CAR 42M unless directed.
Class A require a CAR42M SOM ref ...
CIVIL AVIATION REGULATIONS 1988 - REG 39 Maintenance required by approved system of maintenance
In the case of a Caravan as per AD/ENG/5 if you do not have a CAR42M SOM in place you would have to overhaul the engine at 3,600 hours instead of CASA's generous 5,000 Hour TBO. You will not get 5,000 hours in the USA as a TBO on a PT6A unless you enrolled in a Pratt program with a cost of 10k US+.
The grass is not always greener on the other side of the fence!