Letting them out...
The barrels are not supposed to go in board, they are just for fuelling the plane....
The crates will go in when the cargo door of the An 2 will be open. Actually on
the real aircraft there is a system of dual door: a regular one inside a bigger one.
It is not possible to model it open with the GPM kit as there is an internal frame
which preclude to do so.
Regards