The International Cessna^® 170 Association

I need to replace the wear strips on my upper cowling, the old ones were spot welded on. No one in my neighborhood can spot weld aluminum, wondering if anyone's got any ideas on attaching these?

Thanks.

-Dustin

Mine were also badly worn and I replaced them by grinding out the spot welded pieces and then flush rivet in the replacements. Flush riveting can seem to be a bit of an art, but not impossible.
This of course all done under the supervision of an AP/AI.
per 43.13-b ?!? Not sure I have the book number correct.

I'd considered using countersunk rivets, but the question is what to do with the shop head? I think it would look bad on the outside of the cowling. I've heard there is a method to generate a countersunk shop head as well, but I've got no experience with it. Is this what you did?

Thanks.

-Dustin

Shop heads went on the inside, flush heads on the outside.
Now, the strip I am talking about, is inside the cowling and extends out around the hole where the access door rests upon the stip I am talkin about.
Maybe ya needs try and post a photo of the strip you have in mind.
I know I do not know how to post photos.
Chris

The strips I'm talking about are on the upper cowling, each side, front edge and rear. In my application at least, putting shop heads on the inside would simply have the rivet heads wearing on the boot cowling and nose bowl strips. I would think that this situation would result in relatively rapid wearing of the strips. I'd like to come up with a way to attach these strips so the entire strip would contact to opposing wear strips on the boot cowl and nose bowl.

-D

I don't have a 1948 parts catalogue and I think that is what Dustin owns, but here is a picture of a '52 cowling if that helps:

How about removing the rub strip and grinding the spot welds smooth on the under side. Then make a new rub strip wide enough to flush rivet it to the cowling far enough forward so that the buckheads are located just forward of the boot cowl where they would not be in contact with anything.

countersink the inside of the strip, use short flush rivets and the shop head will fill the countersunk area so you basically end up with two flush rivet heads, inside and out. experiment with the length on some scrap pieces until you get it right.

Countersinking both sides is also an option I considered. However, the thickness,or "thinness", of the skin and the rub strip is such that a countersink on each side is, in my opinion, going to leave a very thin and weak riveted joint. Aluminum of the thickness of that skin is usually dimpled rather than countersunk to protect the strength.

On mine the strips are still present but they were bare aluminum. So I put fiber reinforced teflon tape made by 3M on the aft edges and regular hardware store siliconized weather striping on the fwd edges (due to the relatively large gap) of my cowl. I have only replaced one piece on the fwd left side in three years and 200 + hours. There has been no metal-to-metal chafing.
Steve