The International Cessna 170 Association

Surely the question has asked before. Curiosity.

35 years ago I think I heard of some one rebuilding C170 and C172 wings as flush riveted.

Is this still feasible? What would be the results?

Could one use a std C170 wing rib, convert it to counter sunk configuration w/o having to build a new rib?

Watched a Vashon Ranger video build using CNC match hole flush riveting. Why couldn t same process be used on a C170 Re skin?

I believe the ribs and skins would be too thin to countersink. The method to use flush rivets on thin aluminum sheet is to use dimple dies. I don't see why you would want too though. The result would be alot of wasted time and money.

One might flush-rivet vortex generators rather than glue them.

I believe I would prefer flush riveted vortex generators over glued, some people prefer flush riveted sheet metal repairs as well. Who wants to see a large cluster of round head rivets on the side of their plane like a big scab.

Due to the hyper sonic speeds a Cessna 170 flys having flush rivets on it is a wasted time and effort . While the Cessna 177 had many flushed rivets a friend of mine filled all the dimples left in the skin of his Cessna 177 and painted it like a mirror. Looked good but didn’t fly 1 knot faster or climb quicker . He admitted that time could be used for drinking beer. I told him the amount time you spent on that aircraft if converted to time drinking beer he would be in the ground.

Recently at Oshkosh I looked closely at a lot of 170’s. It appeared that several were giving the flush rivet thing a try. But instead of using MS20427 countersunk head rivets they were just sanding down the MS20470 universal head rivets. I had always been told that if the dimple on a 470 rivet has been sanded down the rivet is unairworthy. I can’t find that in any FAA document though. What I did find was this video from Cessna Structures. For reference MS20470AD3 rivet heads should be .040-.050” high and MS20470AD4 rivet heads should be between .054-.064” high.

Later 180 had flush rivets lots of cracks!

I think sanding down the rivet heads is a good idea... just before installing Vortex Generators.

If the rivets are sanded down not only are they unairworthy so are the surrounding skins.

gahorn wrote:I think sanding down the rivet heads is a good idea... just before installing Vortex Generators.

I certainly hope no one took my previous tongue-in-cheek comment seriously.
I do not agree with sanding of aircraft structural components. I have seen numerous airplanes “for sale” that have fresh paint-work accomplished by questionable methods including sanding in lieu of chemical stripping. Obviously they should be avoided, IMO. Fresh paint is an automatic warning flag in many cases, depending upon the quality and documentation.