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  #1  
Old 01-03-2021, 06:52 PM
Wingit Wingit is offline
 
Join Date: Oct 2019
Location: Miranda,Ca
Posts: 54
Default Elevator counter weights confusion?

I have checked out all of the different ideas about how to make sure the bolts holding counter weights do not become loose, now I am confused.
1 is it possible to achieve proper toque on the fastener holding counter weight.
2 is tight as possible the right torque, if so, will red loc-tite keep the fasteners from coming loose.
3 if you go the nut plate version and there is a void where the nuts and washers were should that be fill with something like RTV to fill the void and anchor the nut plate
4 if you use the nut plate should you stop torquing when the bolt starts to embed in the weight
Thanks
Dave
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  #2  
Old 01-04-2021, 08:48 AM
Bavafa Bavafa is offline
 
Join Date: Oct 2007
Location: Sacramento, CA
Posts: 3,550
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I believe if you make sure the lead weight is well seated on the skin (in its place) and not being held up with any rivet heads, the chance of them to come lose is extremely low. Alternatively you can use the method that is used for the rudder, using nut plates with a few washers in the void area.
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Mehrdad
N825SM RV7A - IO360M1B - SOLD
N825MS RV14A - IO390 - Flying
Dues paid
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  #3  
Old 01-04-2021, 09:03 AM
Wingit Wingit is offline
 
Join Date: Oct 2019
Location: Miranda,Ca
Posts: 54
Default Elevator counter weights

Thanks for the reply
Dave
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  #4  
Old 01-05-2021, 12:24 PM
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czechsix czechsix is offline
 
Join Date: Mar 2006
Location: Spring Hill, KS
Posts: 378
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FWIW on my RV-8A I just snugged the counterweight nuts/bolts down per the plans (using the standard nylon locknuts) and 20 years later they've shown no signs of loosening whatsoever. So I did the same on my -14.

This "problem" reminds me of the Vans SB some years ago for the fuel pickups inside the tank. A few of them came loose and fell off so we were all supposed to open up our tanks and add safety wire. Most likely what really happened was that those fuel pickups were never properly torqued to begin with, and the same issue likely applies to the counterweights.

Make sure the the lead weights are firmly seated against the aluminum rib (sometimes if not properly trimmed the weight can hang up on surrounding rivets in the rib flange, leaving a gap between the weight and the rib, and that could cause issues later making it appear as if the nuts/bolts came loose). As long as the weights are flush to the rib and the locknuts are snugged down you shouldn't ever have a problem...yes the lead will compress a bit under load, but not enough to make them come loose if properly installed. Thousands and thousands of RV's flying around out there for decades with no counterweight issues.
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RV-8A N2D #80583 - built/flew/sold
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  #5  
Old 01-05-2021, 01:40 PM
HishamH HishamH is offline
 
Join Date: Jun 2020
Location: Salem, South Carolina
Posts: 6
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Quote:
Originally Posted by Wingit View Post
I have checked out all of the different ideas about how to make sure the bolts holding counter weights do not become loose, now I am confused.
1 is it possible to achieve proper toque on the fastener holding counter weight.
2 is tight as possible the right torque, if so, will red loc-tite keep the fasteners from coming loose.
3 if you go the nut plate version and there is a void where the nuts and washers were should that be fill with something like RTV to fill the void and anchor the nut plate
4 if you use the nut plate should you stop torquing when the bolt starts to embed in the weight
Thanks
Dave
Google
MS21047L3 Nutplate
Nutplate - 10-32 Thread, Self-Locking Nutplate, Two Lug, Low Height, Cadmium Plated Carbon Steel, 450,, With Dry-Film Lube, Plain Rivet Holes
You will notice that the AN509-10R16 screw is difficult to thread in it, that is because it is self-locking. some people think it is a bad nutplate and they run a tap through it, but then it is not self-lucking anymore. be very careful with that. Call me if you like. Good luck.
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  #6  
Old 01-05-2021, 06:20 PM
mturnerb mturnerb is offline
 
Join Date: Apr 2015
Location: Ponte Vedra, FL
Posts: 1,565
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My approach:

https://turnerb14a.blogspot.com/2017...y-12-2017.html

The advantage of using an aluminum backing plate with nutplates is that you can snug the bolts anytime you feel the need. Torquing bolts, even with washers, into lead is potentially problematic as the lead is soft and easily deformed - if it gives way a bit more over time, bolts can work loose even if the nut hasn't turned. Bridging the two holes with harder material and using nutplates addresses these issues.
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RV-14A built/sold N14VB
RV-12iS in progress as of October 2020

Last edited by mturnerb : 01-06-2021 at 06:39 AM.
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