Smaller Port on Wing Cap?

[collindpyle]

I have lost the cap to go on the smaller hole on the wing. (The black cap that is smaller than the strut service hole) No joy navigating the Piper Manuals. Included is the hole in picture.

Does anyone know what this port is?

Where do I find a replacement? Piper or aftermarket would work...

Thank You all for insight.

 

[voretaq7]

 

[collindpyle]

 

[140B]