You Do Need power plug adapter while traveling from Costa Rica to Chad.

Here is Why You Need An Adapter

The outlet and plug type used in Chad are C, D, E and F and in Costa Rica are A and B. This is how they look like.

Costa Rica

In Costa Rica, outlets of type A and B are in use.

Type A

Type B

Chad

In Chad, outlets of type C, D, E and F are in use.

Type C

Type D

Type E

Type F