What are these holes in the trailing edge of my wings for?

[Halhayden]

I’ve been meaning to ask about these holes (maybe threaded) in the trailing edges of my wings in my DCat. Anyone know?

 

[Sully]

Those are drain holes. Looks like the inboard bays have then at both corners.
Normally, only the lower corner is done.

 

[Halhayden]

Good to know… thanks!

 

[Bartman]

maybe they have extra holes where the fuel tanks are in case of a leak?

 

[Sully]

Probably put them in the inboard bays because the wing is fairly level there.
No harm - No foul.
I usually use seaplane grommets. Especially under the fuselage.