Removal and re-skin of rear hatch on MC-8

[Paladin]

Though I'm fighting the doctor over a time line for back surgery I'm still planning on keeping active until they finally get me down. I have a nasty leak in my ceiling caused by water running around and down the edges of the rear hatch which my plans don't include keeping, I do have plans for a relocated escape hatch. This in mind, I'd like to get up there and get the hatch assembly out and rivet some new skin over it. Those who have done so, can you share any tips? There will not be anything like an ac mounted in or over the old hole, it'll be just closed over.
I'm guessing .080 aluminum,sealer, rivets and possibly added framing if needed.
Would Sika be a choice for sealer?  What type and length rivets? I have a new Harbor Freight rivet gun I've never used and my only past experience has been pop rivets.

How much overlap should there be over the open hole? I thought I saw somewhere to radius the hole corners?

Any help would be appreciated, pictures even better.

-Dave   

[Paladin]

Hmm, I know others have done this. Nobody cares to speak up and help with some advice or pointers?

[Tom Y]

I but a boat hatch there. Had to make it smaller first, took alum and put a slight break around the edges about 3/4" in. Makes the edge stiffer and holds it down. Used a good sealant and riveted down.  Tom

[wal1809]

I have never done it myself.  I was up there not long ago and noticed my hatch cover was not riveted.  It has a lip on it.  It reminds me of one of those plastic storage bins you buy at the Walmart.  I have no idea how it is fastened.

[artvonne]

  Just general knowledge. Radiusing the corners prevents cracking, but the new skin fastened down over the roof should reduce that tendency. However, you could use a dremel with a 1/4" grinder and make a small round cut back in the corners. You may also want to round the corners of the patch so they lay down better. You would likely overlap the opening at least an inch. You can also run a staggered rivet pattern. Not sure of what sealer to use, but dont use anything corrosive to aluminum. You should really use Clecos to do the job right, and anneal the rivets before installing.

[robertglines1]

alum  3/16 rivets at least 3/8 inch long to allow you to colapse GE silicon caulk. If you roll edge add 1/8 inch in length. I laid back hoping some of the pro's would chime in; but that's how I do it.  Bob

[gumpy]

http://www.gumpydog.com/Bus/MC9_WIP/Structural/Roof_Access_Hatch/roof_access_hatch.htm