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Empennage fairing attach holes

R

rv8_builder

Active Member
Hi fellow builders,

I was looking at the plans last night and couldn't figure out if the 10 holes that attach the empennage fairing to the HS have to be dimpled.

The manual states "Dimple the under structure using n pneumatic or hand squeezer. Dimple the rivet holes in the skins using a C-frame dimpling tool"

How is the empennage fairing attached and is it necessary to dimple those holes :confused:
 
I forgot to dimple mine when building. Instead I countersunk the fiberglass
fairing and installed it with tinnerman washers. Looks good and I've had no
issues to date.
 
Same here, I countersunk the fiberglass and used tinnerman washers. I also modded my fairing and inspection plate. Much nicer and cleaner look.

-Jeff

http://jeffsrv-7a.com/FUSELAGE/04-08-26.htm

FUSELAGE%20129.jpg
 
Thanks guys :)

I also got a reply from Van's today as follows:

"No need to dimple the fairing holes, because the fairing itself is thick enough to countersink"
 
Any suggestions on what to do if you already dimpled the fairing attach holes? JB weld?
 
tinnermans and a layup...

I too used tinnermans, but also modified the fairing with a wraparound at the leading edge. I then chopped the "tails" and did a layup allowing the emp fairing to overlap the aft pieces. This makes the emp fairing easier to remove and also avoids scratching the vertical stab when you remove it.
dsc01591xl9.jpg

dsc01590eo4.jpg
 
Installing nutplates

Is it a good idea to install the nutplates for the the fairing while buildug the empennage? It is not possible to deburr and prime between the two layers of metal after drilling, when the empennage is finished and and installed to the fusselage.
Thank You.
 
Twofer

briand said:
Any suggestions on what to do if you already dimpled the fairing attach holes? JB weld?
Click to expand...
Is it a good idea to install the nutplates for the the fairing while buildug the empennage?
Click to expand...
To answer the first question, I would simply UNDIMPLE the hole. Fears of weakening the metal are greatly overexaggerated. I have done this many times when I accidentally dimpled a hole in error. Personally, I would avoid the use of JB weld anywhere on an airplane, but that's just me.

To answer the second question, I would wait until the empennage group is permanently affixed because the fit of the fiberglass fairing cannot be known until then. Not only are all RV's slightly different, but the fairings are individually unique. Some fit better than others right out of the box while others may require extensive rework. In general, the fewer fasteners it takes to finally affix the fairing, the more pleasing the look and you cannot know at this time where minor surface mismatches will occur.
 
Nutplates

I agree, I would suggest to drill nothing at all until all components are bolted together. As others mentioned, the fairing often fits so poor that you have to do them over again.
But how to install a nutplate when there is not enough room to reach with a bucking bar? This problem will show up in some places like the wing root fairings and the emp fairing as well. Solution is simple: Just rivet a nutplate flush to a 1x1 piece of scrap (thick enough to CS for the rivets) and then take some structural adhesive (auto-shops use them to glue on spoilers and so on, it cures somewhat flexible compared to JB weld), fumble the piece in place and insert a cleco from the outside. There is no chance to ruin your tailcone or whatever while riveting without enough sight/space, and I see no drawbacks (OK, a little more weight..). This way you can install nutplates in areas where it would be otherwise impossible.
 
rv8r said:
.........how to install a nutplate when there is not enough room to reach with a bucking bar? ........you can install nutplates in areas where it would be otherwise impossible.
Click to expand...
Dirk,
Your tip is clever and a great idea. I offer this notion......concerning the practice of using a rivet gun to attach nutplates. Other than a couple of nutplates attached to the web of the main spar and one or two located extremely close to the ends of the training edges of the control surfaces, I cannot recall a situation I've run into in which nutplate attachment could not be accomplished with a hand or pneumatic squeezer. Surely a hand squeezer should be able to access those nutplates attached to the empennage fairing and wing root fairing area. Still, your idea is great for those builders who may not have a suitable yoke for reaching limited access areas. Alternatively, the use of blind rivets as recently discussed in this thread http://www.vansairforce.com/community/showthread.php?t=15564
though pricey, will certainly reach where any solid rivet would otherwise be difficult to set and like your idea, carries with it no risk of potentially denting the structure.
 
I'm with Rick on squeezing - I have so far done every nutplate with my squeezer, and would certainly not worry about using a pulled rivet if I couldn't do that. I do like the bonded on idea, though. Year before last at Oshkosh I looked at some Click-Bond glue on nutplates. Very cool and easy to install, but as you might expect, really expensive. Remember, the rivets (or bonding in Dirk's case) are not holding any airframe parts together - they're just to keep the nutplate from falling off when the screw is not in place.
 
Well, I just realized these are installed with #8 screws and my holes and c-sinks are only #40 so after I drill to #19 almost all the c-sink will be gone.
 
Rick6a said:
To answer the first question, I would simply UNDIMPLE the hole.
Click to expand...


I know I´m a bit late to the party here. What´s the best way of undimpling the hole? I´ve accidentally put dimples in the Vert Stab skin on one side. Not dimpled the rib beneath for these holes though. So I have either got to dimple the rib too or take the dimples out.

Thanks
 
rivet squeezer with flats

I'd use a rivet squeezer with flat dies. Take care to not over squeeze. Welcome to VAF, BTW! :)
 
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