Sorry about the lack of details. I had it all in my mind and didnt type it out.
But, yes, these are accessable from ground ladders, about 20'.
They have ducts that are about 40' with no access panels. From the hood, goes up 4-6' and then turns into the 40' run to the wall fans.
The only good way to get to the duct was to take the fans off, like a roof mounted fan.
We already did these, I was just looking for tips for next time.