The Cessna 120-140 Association Forum

Yep, it's cracked... a lot. Anyone have info on how they repaired this area? John C?

If I put a doubler over the top the latch won't be positioned correctly. Seems like the most correct way to fix it would be to remove ALL the damaged area, put a "flush" patch there and make the rivet lines/doubler outside the latch area.

That dude is a little messed up! You have a couple options.

I like option A. find another door.

Option B, replace that whole piece. Or at least as far back to get away from the tricky edge, door controls etc. That would be the approach I would take.

A little hard to tell exactly from the photos. First, you want your repair to handle tension from the upper to the lower hinge area, which means no butt splices (have to overlap to transfer the tension load). Doubling in the edge is going to increase the thickness of the edge of the door. I'm not sure if that will cause a problem or not. Doubling in the raised inner area should not be a problem.

Can you post a photo that shows all of the damage at the trailing edge of the door, and as much of the center as practical?

Here is all the damage outlined with fine sharpie.





The wide sharpie is where I think I should make my cut an form a new piece.

Well, I went to town on the door tonight. Cut out the bad, made some new.







Tomorrow I will make the doubler to go around the patch. I am going to put it on the outside rather than spend countless hours trying to mount it internally and having weak points near the window .

I would have cut the patch bigger to get overlap in the two areas circled below. The door tends to pull put at the top rear corner in flight so you need to retain rigidity in that direction. I think you can easily overlap everywhere, except possibly right at the door edge. If your overlaps elsewhere are solid you might get away without doing it there, or stagger the joint so it doesn't align with the adjacent part of the patch, like the red lines.

I plan on adding a doubler all the way around on the inside of the door like this insertion patch since I need to get access to the inside of the door for bucking rivets anyway.



The only place it can't go inside the door is on the window sill because it is tack welded. I will add a doubler on the outside for that spot. Seem reasonable?

Hard to visualize. Are you \saying you'll have three thicknesses along the door edge? It is that continuous "Z" section that gives the door its rigidity. I don't think you need a doubler, but you should use overlapping seams.

Yes, I plan to have three layers down the door edge. The patch is the same size as the section I cut out so there is no overlap with the old material. I will use a doubler as my overlap as with a typical flush patch repair. The doubler will be sandwiched between the outer door skin and inner door skin. I'll draw an example later.

OK, that should be fine. I was concerned that the extra thickness along the edge might be a problem. Be sure you use enough rivets (per AC43-13) on each side of the splice(s).