Same same in PNG, need a 10% power margin for slingload ops but only when pax are carried on board. Any pax so carried must be associated with the load; eg if you're carrying a net full of Telikom gear up to the top of a mountain, you can have a Telikom employee onboard to help dismantle the load on arrival.
However, when lifting from sea level to altitude then ops manual requirements for OEI or OGE power margins might kick in as well.