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  #11  
Old 04-13-2016, 08:54 PM
rjcthree's Avatar
rjcthree rjcthree is offline
 
Join Date: Jan 2007
Location: Bay Village, OH
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Default How does it happen?

Assuming the bolts were tight, is it loosening of the bolt(relative rotation) or simple material creep? I'dvote creep, which means it's something we've all got to check periodically, as the failure mode is fugly.
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  #12  
Old 04-13-2016, 09:14 PM
N743RV N743RV is offline
 
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Location: Livermore, CA
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It is definitely a creep problem with the lead...it's a low melting metal and has a relatively high creep rate at ambient temperatures. I didn't mention it but there is a mating lead weight on the fairing side..that's why a nut plate wasn't specified...not a great design. Too bad that I was a real rookie when I built the empenage or I might have come up with a fix at the time.

Still hoping to hear some suggestions for bonding the weight to the rest of the assembly.

By the way, the weight is only slightly loose and is in no danger of causing an interference problem with the stabilizer. But I do worry about vibration causing it to continue to creep and making the assembly even looser.

Bob Cowan
N743RV
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  #13  
Old 04-13-2016, 09:43 PM
BillL BillL is offline
 
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Location: Central IL
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Quote:
Originally Posted by N743RV View Post
It is definitely a creep problem with the lead...it's a low melting metal and has a relatively high creep rate at ambient temperatures. I didn't mention it but there is a mating lead weight on the fairing side..that's why a nut plate wasn't specified...not a great design. Too bad that I was a real rookie when I built the empenage or I might have come up with a fix at the time.

Still hoping to hear some suggestions for bonding the weight to the rest of the assembly.

By the way, the weight is only slightly loose and is in no danger of causing an interference problem with the stabilizer. But I do worry about vibration causing it to continue to creep and making the assembly even looser.

Bob Cowan
N743RV
I think the concern, with even a little looseness, is flutter. I have the same design and had those thoughts of not liking a fastener holding lead in a moving part (as I followed the instructions).

To the present - - Now. as an experienced builder, what would you do to "fix" it? ProSeal the back? Hysol? Bond a stainless backer and make a steel hat shaped retainer for proper bolt tension? Recast with a brass matrix? Removable tip and just retighten it on annual?
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  #14  
Old 04-13-2016, 09:56 PM
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Captain_John Captain_John is offline
 
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Whoah, whoah, whoah...

I had the same problem.

The bolt didn't loosen up, the nut simply bottomed out on the bolt threads.

You need to install a washer on the nut side.

It is an elevator trim cap. Drill it off, put on the washer and re-rivet it back on!

Paint the heads of the rivets as necessary.

Is this a show plane or a go plane?

CJ
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  #15  
Old 04-14-2016, 12:13 AM
N743RV N743RV is offline
 
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My build photos do show a washer under the nut as called out for in the plans. Also, the assembly was very tight initially and has only loosened over time. But maybe removing the tip fairing may be required.

Bob Cowan
N743RV
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  #16  
Old 04-14-2016, 04:53 AM
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Captain_John Captain_John is offline
 
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yes I know there is one under there now. Put in another one!

CJ
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  #17  
Old 04-14-2016, 06:52 AM
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GLPalinkas GLPalinkas is offline
 
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Default

Quote:
Originally Posted by Captain_John View Post
Whoah, whoah, whoah...

I had the same problem.

The bolt didn't loosen up, the nut simply bottomed out on the bolt threads.

You need to install a washer on the nut side.

It is an elevator trim cap. Drill it off, put on the washer and re-rivet it back on!

Paint the heads of the rivets as necessary.

Is this a show plane or a go plane?

CJ
+1 - fix it the correct way. Repainting rivets. Question remains: Is this a show plane or a go plane?
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  #18  
Old 04-14-2016, 07:12 AM
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I use proseal to bond the weights to the structure when I install them (in addition to the bolts),
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  #19  
Old 04-14-2016, 08:31 AM
RV74ME RV74ME is offline
 
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As a new builder (still building the empennage), I had similar concern about the rudder counterbalance weight. After riveting on the top rib above it, i thought "how will i ever know if this thing comes loose?".

Is this a concern for any of you experienced folks, or should be not worry about it?
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  #20  
Old 04-14-2016, 12:48 PM
BillL BillL is offline
 
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Quote:
Originally Posted by Walt View Post
I use proseal to bond the weights to the structure when I install them (in addition to the bolts),
Thanks Walt!
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Lord Kelvin:
I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.
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