Old Rivets

[CPSONE]

I've read that heads may split and other problems might come from using rivets that are too old. Anyone know how old is too old? I bought an un-started (no rivetting done) -7 emp kit that's from 2005. Should I get a new full set of empennage rivets?

[Mel]

This has been brought up over time. I have rivets in my shop that are over 25 years old. They are fine.

[mcencula]

...if they work, great. If they crack or don't drive right, pitch 'em and buy some new ones. I had some that are ~5 years old go bad. My brother (RV-6A sloooowww builder) has lots that are still good after 15 years. He also ran into some that were bad, too, though.

Good luck.

[CPSONE]

Thanks for the replies. I'll give them a try and inspect.

[aarvig]

So if rivets go bad in 5 to 10 years does that mean we have to replace our airplane in 5-10 years? If an old rivet can't handle the pressure of being driven I doubt it could safely handle the G loads these planes are designed for. Go with Mel's advice...he's the one that would know.
Unless they have been stored in salt water I wouldn't worry about it at all.

[David-aviator]

Originally Posted by aarvig

So if rivets go bad in 5 to 10 years does that mean we have to replace our airplane in 5-10 years? If an old rivet can't handle the pressure of being driven I doubt it could safely handle the G loads these planes are designed for. Go with Mel's advice...he's the one that would know.
Unless they have been stored in salt water I wouldn't worry about it at all.

Aaron,

I think the issue is rivets get hard when driven but sometimes they get hard before being driven and are difficult to set and may crack. Why that happens but I don't.

I bought a ton of old rivets from the Boeing Surplus Store in Seattle once and many of them were so hard they were useless. There's nothing more frustrating than trying to drive an old hard rivet. But I've never heard of RV rivets going hard before being driven.

I also read somewhere that heating old hard rivets will make them soft again, but that doesn't seem worth the effort considering how cheap they are new.

[aarvig]

Originally Posted by David-aviator

Aaron,

I think the issue is rivets get hard when driven but sometimes they get hard before being driven and are difficult to set and may crack. Why that happens but I don't.

I bought a ton of old rivets from the Boeing Surplus Store in Seattle once and many of them were so hard they were useless. There's nothing more frustrating than trying to drive an old hard rivet. But I've never heard of RV rivets going hard before being driven.

I also read somewhere that heating old hard rivets will make them soft again, but that doesn't seem worth the effort considering how cheap they are new.

Is it possible that the old rivets had a composition problem and that is why they were in the surplus store? I have a hard time believing that an aluminum rivet will actually harden over time unless it is subjected to some sort of environmental stress...correct me if I'm wrong.

[az_gila]

The rivets are made to a Mil-Spec. If they had an "expiration date" then every batch would be required to be marked with the date of manufacture - just like some Mil-Spec hoses.

The Mil-Spec has no mention of dates, so the rivets are not date limited...

http://www.everyspec.com/MIL-SPECS/M...74F.008075.PDF

Added

The Boeing surplus rivets may have been surplus because they did not meet the specifications.

I did like visiting that store....

[tjo]

Rivets don't go bad over time. If they are stored in a corrosive environment, they can, like if an aluminum rivet was exposed to ammonia stored in a closet, for instance, but just time will not do it.

The Boeing surplus rivets were probably made of some material that behaves differently than you expected it to, like a rivet that was intended to be driven while hot or something. If they had a batch of known bad fasteners, I doubt they would have resold them.

Tim

[rv7charlie]

http://www.google.com/search?aq=f&so...ening+aluminum

or, specifically

http://www.2nd-hardener.com/aluminum-alloys.htm

I'm too lazy to see where the alloy used for Van's A/C rivets falls in the scheme of things....

Charlie