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tailcone queries

D

dinowal

Active Member
Hi fellow builders, Currently ready to install static system, & it appears that that a static line goes only to the ADAHRS unit & no further forward in the Aircraft. How does the panel mounted Skyview unit know the altitude? I presume the ADAHRS unit communicates electronically with the Skyview? I was contemplating adding small backup Altimeter & Airspeed indicators in case of the Skyview going black one day, does this mean I need to run a separate static line forward? Is this a necessary & good idea anyway? Thanks for any comments...
Also, I have recently completed the F-1211 bulkhead assembly, & am completely mystified as to why the top 4 of the 8 nutplates are attached with AD426 squeezed rivets, & the bottom 4 use CCR-264SS rivets. I had never seen these rivets before & was very surprised when the mandrel pulled straight through! I have followed the Vans instructions to the letter, but cannot think of the engineering reason for the use of these two types of rivets.. Any ideas? Thanks, DEAN...
 
I had installed a backup airspeed indicator originally, but when Dynon came out with the D1, I scrapped that idea and plan to use the D1 for my backup information. You may want to look into doing the same.
 
The pitot line AND the static line AND the AOA line (if you put one in and you should) go to the ADAHRS. As does the OAT. The ADAHRS is a computer that takes all of those inputs and computes a variety of info it will transmit to the D1000 via wires. So if you want static in the panel you will have to tee off and run it up there. Your pitot will pass through the panel area as it goes aft to the ADAHRS. So you could tee off as it passes by. This is different than how the earlier D-180 pneumatic signals were routed.

The CCR rivets are generally used where squeezed rivets cannot be accomplished using the 3 inch yoke. Yokes are expensive and the vans tool list to build the -12 only specifies the 3 inch yoke. They do pull a little differently than the LPs, you will soon get the hang of it! They take a different size "nozzle" and I found that the cheapest hardware store puller was the best tool for them compared to the "better" pullers I was using on the LPs.
 
G?Day Dean.

Don?t know the answer to your first question, but here?s what I encountered as to the rivet matter (just now finishing up the tailcone):

I also wondered about the CCR rivets, so I looked up their data sheet. Cherry makes them specifically for attaching nutplates, BUT?their literature clearly says the mandrels are supposed to be retained. The fact that they pulled all the way out causes me to wonder if the result then is an indeterminate structure. All true what they say that the only function of these rivets is to prevent the nutplate from spinning, but again there is a BUT. The difficult accessibility of those nutplates in the finished assembly means that if by any misfortune a nutplate did spin, one would be well and truly messed up. In the interest of eliminating any uncertainty relating to the attachment of a flight safety critical assembly, I replaced the rivets with AN426s.

The gentleman who is serving as Tech Counselor for my project agreed that was the best way to go. Please note that this is not a recommendation, just a description of what I did on my project, for which I am responsible.

As to the why part of your question, my understanding (always subject to critical scrutiny) is that Van?s designed the RV-12 so that any solid rivet application is reachable with a hand squeezer outfitted with a standard 3? yoke. Those eight rivets would require a shorter yoke, which translates to another hundred or so dollars in tool cost.
 
Dean.. I am having much better luck pulling the CCR-264SS rivets using a dedicated hand rivet puller, not my close quarters tool, with the _appropriate_ sized nose piece. The last CCR-264SS sets of rivets all went down fully and the rivets do not spin. I am building the fuselage, so it could just be I am becoming more familiar with these rivets, but I think not so much.

Jeff
 
What works best with these CCR rivets is to put the nutplate in place with a screw so that the nutplate is tight to the structure and then rivet the CCR rivets. If you hold the nutplate in place with just clecos the result will be that the nutplate is a bit "loose".
 
On some nut plates I was able to use a Cleo instead of a screw to hold it tight. A real timesaver over using a screw. When that didn't work I put washers on the screw so it caught only a few threads.
 
Also be aware that when you dimple the nutplate's attachment holes, the nutplate's arms are sometimes slightly bent and need to be manually straightened-out so they both lay flat against the mounting surface.
 
DHeal said:
Also be aware that when you dimple the nutplate's attachment holes, the nutplate's arms are sometimes slightly bent and need to be manually straightened-out so they both lay flat against the mounting surface.
Click to expand...

Yup. I hold a force in opposition to the bend when I dimple leaving just a bare minimum of concavity in the nut plate such that one cleco holds the nut plate adequately flush against the sheet metal. That and the appropriate size nose piece on the hand rivet gun results in a non spinning rivet for me. Disclaimer: Your mileage may vary :)

Jeff
 
Thanks for help..

Thanks Bill for your very clear description of the ADAHRS & Skyview operation, & thanks Don for the Dynon D1 Suggestion... will look into that one. Regarding the rivet query I was too dense to realise that it was access by the squeezer that was the factor. John H: the Cherry Nut Plate Rivets page I looked up describes the CCR264SS rivets as "low cost pull through style rivets" & the sectional drawing on the right seems to me to indicate no mandrell left in, although it's not totally clear. I definitely have the correct size holes, ( No. 40), so I think my rivets are set correctly, - (there is a hole right through them). I do have a 4" squeezer yoke, so can replace them if it's established that they are faulty.. Cheers, DEAN...
 
Dean,

The data you accessed apparently was correct. I double-checked and discovered the "spec" I pulled up before was posted by a vendor. Aha, let that be a lesson to me. I also found a Cherry data sheet that did not state one way or the other about the mandrel retention. I'm assuming that was an older, obsolete pub. As long as your rivets are fully set and flush, you should be in fine shape. Good to have it clear, thanks for the back-up.
 
progress

Thanks John, I feel confident to march on! I seem to be at the same stage as you, - will finish the tailcone in a few days. I am really inpressed with the photo of you & the tailcone & stabilator, very neat job in a very neat workshop. Whilst I have left some of the blue plastic on, I have basically torn the rest off, so it looks a little rough.. Like you I intend to keep the parts separate, & hopefully get them painted individually elsewhere before assembly. Currently at about 150 hours. Cheers, DEAN...
 
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