[RV7Guy]

A friend of mine is the IA for a University Aviation program. The U became the owners of an abandon RV6A project. He said the tail group is done and the workmanship is excellent. The wings are done and the workmanship is also excellent. He told me the wings skins were attached with Cherry Max flush pop rivets.

The University is going to sell the project because of liability concerns dealing with an Experimental aircraft. This decision was made before the airframe was received and has nothing to do with the use of the Cherry Max rivets.

I told him I would post this to the group and see if anyone has used Cherry Max for construction of any part of an RV. He will be calling Van's tomorrow to see if they have any engineering concerns.

Thanks in advance.

 

[jdmunzell]

They're great but expensive!

Spoke with Tom at Vans the other day about Cherrymax rivets and structural reliability. He told me that you could build the whole airplane them! The problem is that they are expensive.... about a $1 a piece. Okay for small jobs. but prohibitively expensive for larger ones...like all the rivets on the wing skins!. But then again in this instance, that isn't a concern for you.

 

[osxuser]

I wouldn't. Pulled rivets aren't as good because they don't stand up to vibes as well. I do like Cherry's, they have a place in aircraft construction, but I don't like them for building a whole wing... sorry, but there is just no replacement for solid bucked rivets.

 

[az_gila]

Question for them...

Since CherryMax don't make structural rivets in 3/32 diameter, was the wing riveted on with 1/8 CherryMax rivets and bigger dimples?

Or was it some non-structural Cherry rivet used in the 3/32 size?

Big difference......

gil in Tucson

 

[Rick6a]

Since CherryMax don't make structural rivets in 3/32 diameter, was the wing riveted on with 1/8 CherryMax rivets and bigger dimples?..............Big difference......gil in Tucson

I would echo that. There are Cherry rivets and there are Cherry rivets. Some people can be rather cavalier about describing all Cherry rivets as max. Examine the heads of those alleged structural rivets carefully. The center stem should NOT break off below the surface of the rivet. In no case is a center hole allowed. Using the correct grip length and set professionally, the solid stems of a structural CR3212 would normally break off slightly high and a rivet shaver would be then be used to flush the stem to the surface. If the plane was assembled with CR3212 Cherry max rivets, I would have absolutely no problem at all with long term structural integrity. But at a cost easily exceeding $0.50 per fastener, I can't imagine the original builder went that route.

 

[briand]

Scrap aluminum fetches a little over a dollar a lb., use that money towards a new kit.

 

[C-GRVT]

Perhaps interesting to note in this discussion is the following quote from Van's construction manual for the 6A (circa 1991)

"Optional Skinning Procedure"

Those who choose may install the bottom wing skins using AVEX CS4-4 or MK-319-BS POP blind rivets. This procedure will permit the bottom skin to be riveted on last, and will somewhat simplify the otherwise awkward riveting procedure. However, the blind rivets, though flush headed, do not leave a finish as smooth as do AN426AD3 rivets. This is the primary reason for specifying that the bottom rather than the top skins be blind riveted......."

Bill Brooks
RV-6A fuselage under construction,
wings finished using all solid flush rivets, top and bottom

 

[RV7Factory]

What about weight? I wonder how much, if any, weight would be added by using -4 cherrymax rivets in lieu of -3 solids. Overall it is probably negligible, but I am curious.

 

[Mel]

NOT negligible. Pulled rivets weigh considerably more than solid driven rivets.