This is another area to check on your Huey. We inspect this area at least once a year. You can’t see the crack unless you pull up the floor panels over the lower fuel cells. We plan it so when the aircraft you want to inspect has flown in at the end of the day and it’s below 300 lbs. of fuel. You can pull the floor with out a problem. Never pull them with the cells full as the fuel weight from the aft cells will swell them up and you can’t put the floors down with out defueling. I also suggest not trying to put a sealant between the floor panels and the structure. You not sealing any thing, all the tie-down rings are not sealed and any liquid passes into the cell area. There are drain holes at the front & aft inner channel of that cell area they are about a half inch in diameter. I have seen panels damaged when trying to pull-up ones that were sealed down, they are made to be removed. Back to the areas to be inspected. The areas that crack are covered inside and out by vertical structure as you will see in the photos, that is why you have to pull the floors.
Hope this helps and that you find no problems. ( keep looking ) More later
Pete Sacramento Fire