You Do Need power plug adapter while traveling from American Samoa to Papua New Guinea.

Here is Why You Need An Adapter

The outlet and plug type used in Papua New Guinea is I and in American Samoa are A, B, F and I. This is how they look like.

American Samoa

In American Samoa, outlets of type A, B, F and I are in use.

Type A

Type B

Type F

Type I

Papua New Guinea

In Papua New Guinea, outlets of type I are in use.

Type I