Mmmmm ...
I have a suspicion that is no longer allowed by PNG authorities ...
I do remember that when I escaped from the place in '91 that all of the 'Columbia' Vertols were then carrying P2- registrations having been allowed for some time to remain on their N- registrations ...
It is possible (?) that for 'short term' contracts some a/c may be allowed to remain on their home registrations but I'm really not sure about that !!
Cheers