door frame rivet heads missing

[rydfly]

While unloading the plane after a great weekend vacation with the family this evening, I noticed 3 rivet heads missing along the horizontal surface of my passenger-side door frame. I'm due for annual by the end of this month, so we'll be inspecting for corrosion and such anyway, but can anyone tell me if this area specifically is inherently troublesome on our 170's? Is there something that could cause these rivets to fail like this, other than corrosion? It's entirely possible they were 60 yr-old originals.

[Bruce Fenstermacher]

Certainly more experienced opinion here but that is a odd place. I wonder if you will find corrosion, likely caused by animal urine as that area above would be a nice nesting place I'd think. But then I'm not a mouse so I could be way off base whether that is an ideal nest location.

You just might not find anything that would give you a clue as to why those rivet heads popped and those next and in between have not.

[GAHorn]

Using a common screwdriver blade and a small hammer, lay the blade along the adjacent or middle rivet head and give it a light "tap"...
If the head pops off easily... then it was ready to fail anyway. This is an area below the wing-root where water can seep aft when parked (especially outside) and contribute to corrosion.

[flyguy]

I wonder if you will find corrosion, likely caused by animal urine as that area above would be a nice nesting place I'd think.

Funny that you would mention pee. . . I hangared Delta at a little country strip northeast of Kansas City just before I brought her to Louisiana. While in transition and moving all our stuff here, Delta sat out here on the pad. A few weeks had gone by before I came back, and it was a real shock when I opened the door and that smell nearly knocked me down. Delta had been sitting outside here just a few short weeks but I assume the mice had done their dirty work while she was sitting in that open hangar in MO. The little buggers had made nests over both door frames and bringing the plane to the rainy humid conditions here in LA, caused the moisture reacted with the mouse pee. I took out the headliner, side panels, seats and all the carpet . It was a messy but when I finished the cleaning and neutralizing process, I zinc chromated the areas above the door frames. Never saw the critters before we came here but have never had them show up since. Next on the hit list - - LOOKING TO ELIMINATE THE MUD DAUBBERS.

But then I'm not a mouse.

YOU SURE ABOUT THAT? YOU COULDA FOOLED ME

[rydfly]

It's exactly as expected. I inspected above the headliner last night with a mirror and flashlight and things looked generally good. However, looking straight on at the seam between the two riveted layers you can see the corrosion which has eaten the rivets. The one in between the missing locations is only held on by the paint.

Looks like an expensive annual ahead. Cessna thinks those door frame parts are made of gold... Not to mention all the labor involved to replace. Anyone done this repair before? Do the wings have to come off, or is there enough access with the fairing strip removed?

(Sigh )

Part #'s required:

Door frame upper outboard 0511000-6 (left), -7 (right)
" " inboard 0511000-22 (left), -23 (right)

The outboards appear to still be available new, for A LOT of $$$. Inboards are unavailable. Options other than salvage yards?

[wingnut]

Do you really need the upper door sill parts? If they aren't bad, you can just drill them off (or finish "popping" them off ), clean and apply quality primer and shoot it back on.

[rydfly]

Do you really need the upper door sill parts? If they aren't bad, you can just drill them off (or finish "popping" them off ), clean and apply quality primer and shoot it back on.

I guess I just assumed the worst... That corrosion = end of life for any airframe component. I guess it doesn't hurt anything to wait until they're removed before we condemn anything if there's a chance any of the parts can still be salvaged. It all depends upon what the definition of "bad" is.