3top,
It has been a while since I flew those dinosausorus. If I remember correctly, there are 2 sets of different equipments :
- the regular Cargo Swing which allows up to 750 kgs
- the ERC system that consists of a reinforced frame underneath the fuel tank and goes up to 1100 kgs
These equipments come straight from the factory and don't need any STC except for external mirror, depending on local regulations.
I have never heard of any factory authorization.
Cheers
ATN