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  #31  
Old 04-25-2009, 03:10 PM
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az_gila az_gila is offline
 
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Quote:
Originally Posted by David-aviator View Post
.....
The MS21042 nuts do weigh less than any of the other nuts and are quite strong for their size. I believe they came out of NASA space age technology.
...great in a shear application - but poor for this particular tension application.

It's relevant test with interesting results.
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  #32  
Old 04-25-2009, 06:43 PM
scsmith scsmith is online now
 
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Default Dan H is correct on all counts

What Dan said is right. See my new post called "A Tale of Two Airplanes" if you care to know what I am up to.
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  #33  
Old 12-23-2012, 04:58 PM
mspenc45 mspenc45 is offline
 
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Question Bracket gaps - Landing Gear

OK guys, I figure this is as good a place as any to post this question. I just switched over to the 12 point NAS1804-5 nuts, and also the NAS6606-27 bolts, which are slightly longer, thus giving a few threads through the new taller nuts. These nuts are certainly easier to get on with a socket to torque, but I have another issue. My gear both had no gap in the front but about the 0.035 recommended in the rear between the bracket and plate. By being careful in the torquing process, going back and forth I ended up with about .010 gap, both front and rear on the left, but on the right .003 front and .014 rear, and all gaps varied between the gap at the inside, closest to the gear leg, and on the outside of the bolts, away from the gear legs. I've read about removing them and taking material away, but is shimming a possible solution? I don't know about other RV-8's, but getting the bracket completely out requires the removal of my vent and fuel fittings. Hardened shim stock in the recessed area of the bracket, between the leg and bracket, would increase the gaps, but I am not sure the same quality of results.
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  #34  
Old 12-23-2012, 06:03 PM
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GAHco GAHco is offline
 
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Exclamation Better Bolts, Nuts and maybe washers!

Gahco has 12 point bolts (MS21250-06028) 180Ksi plus.

We also have 12 point nuts that are rated to 220 ksi and they are nylon locking, this means little if any thread galling.

We have washers flat and counterbored hardened to 260 ksi.

I will get exact item #,s as I am at home and not all of thes items are on the webstore.

The 12 point bolts do have a taller head than the Vans bolt.

I am building a 6, so I am open to suggestions about the RV8,s

GAHco will consider additional discounts for RV customers. Let us know what your thoughts are?
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Last edited by GAHco : 12-23-2012 at 06:16 PM.
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  #35  
Old 12-24-2012, 01:59 PM
madhun madhun is offline
 
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Default

An interesting read and excellent discussion. One thing I'm fairly certain of is that I sure don't want to be in the aircraft when either the nut, bolt or anything surrounding it lets go!
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  #36  
Old 12-24-2012, 02:25 PM
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Mark, how many hours on on the plane? The small gap may be a result of wear on the wear plate. It should not be that hard to change if that is the problem, if I remember correctlly, it is held on with two 1/4 in bolts and nuts. Also, I don't think shaving a Few thousandths off of the u bracket would Not hurt.


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Last edited by bird : 12-25-2012 at 07:38 AM.
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  #37  
Old 12-24-2012, 04:21 PM
scsmith scsmith is online now
 
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Default No shimstock

Any kind of shim between the saddle bracket and the gear strut is likely to walk/work its way out over time.

Just remove the saddle and grind 0.010 or so off the ends. Not sure why you need to get the vent and fuel lines out to get the saddle out -- I don't think you should have them that close to the saddle. The brake line does run by pretty close, but I think you can squirm the saddle bracket out without taking anything else off. Probably don't even need to jack the plane up, as long as you don't move it with the bracket off.

And one other point for emphasis - reading back through the old thread, there were a number of people who said that there were no known failures so why fix it -- when in fact, at that time there were at least two known failures. Since that time, a few more cases have also emerged. Some failed on landings, some were found loose on inspections.
An interesting thing about the failure mode of the horrible NAS679A6 nuts is that they have inadequate hoop strength around the thread, so when loaded in tension, they stretch circumferencially, climbing up the ramps of the threads. At a certain point, they actually leapfrog over a thread, and are now loose by a full thread, without ever turning. Some folks have looked at them after finding them loose and say the threads look OK so it must have just loosened (by turning) but I have witnessed the leapfrog-mode and I really think those old nuts are trouble.
I happened to be looking at my old preview plans, which date from a time about 8 years before I bought my kit. It was interesting to note that as of that point, the call-out for the gear nuts was for AN365 - which would be a somewhat better choice, but still not as good as the strong NAS 1804-6 nuts.


Quote:
Originally Posted by mspenc45 View Post
OK guys, I figure this is as good a place as any to post this question. I just switched over to the 12 point NAS1804-5 nuts, and also the NAS6606-27 bolts, which are slightly longer, thus giving a few threads through the new taller nuts. These nuts are certainly easier to get on with a socket to torque, but I have another issue. My gear both had no gap in the front but about the 0.035 recommended in the rear between the bracket and plate. By being careful in the torquing process, going back and forth I ended up with about .010 gap, both front and rear on the left, but on the right .003 front and .014 rear, and all gaps varied between the gap at the inside, closest to the gear leg, and on the outside of the bolts, away from the gear legs. I've read about removing them and taking material away, but is shimming a possible solution? I don't know about other RV-8's, but getting the bracket completely out requires the removal of my vent and fuel fittings. Hardened shim stock in the recessed area of the bracket, between the leg and bracket, would increase the gaps, but I am not sure the same quality of results.
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Last edited by scsmith : 12-24-2012 at 04:33 PM.
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  #38  
Old 12-25-2012, 01:35 AM
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Andy Hill Andy Hill is offline
 
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Default

Hi Steve...

Interesting thread / research.

I know structures / loads to a basic level, but nowhere near yourself, so it is a god education

Just fitting a Grove Gear, and it was supplied with:
  1. NAS 6206-36 Bolt (longer than Vans plan due thicker leg (?) and maybe longer nuts)
  2. MS14183L-6 Washers - I have no idea of the merits between various washer types, I am sure you will let us know [Vans plans use 062-25783054]
  3. NAS 1804-6 Nuts as you are tending to...
If you are looking to up the strength for soft field, I would think the first line of defence is the larger tyre (380-150-5)?

Whilst I can see a broken bolt or nut is preferably to a damaged gear tower, it misses the point that I would think a load that breaks the bolt or nut is very likely to see this followed by the leg folding with associated wing/fuselage/propr/engine damage.

Vans do give some detailed explanation of how to set this up, but seems more concerned with wear aspects than configuring the components for Ultimate Strength.
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  #39  
Old 09-26-2013, 04:26 AM
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chepburn chepburn is offline
 
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Location: Ottawa , Canada
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Default Service bulletin ALERT

Hi all,

Canada just issued a service bulletin for MS21042-6 nuts.
http://www.tc.gc.ca/media/documents/...sa-2013-04.pdf

Although this isn't the preferred nut here in Steve's study, some of you may be using it.

Just a heads up.
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Last edited by chepburn : 09-26-2013 at 04:35 AM.
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  #40  
Old 09-26-2013, 05:53 AM
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grubbat grubbat is offline
 
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Default Thanks

Thanks Steve for your post. Very informative.

We used a lot of those NAS nuts building jet engines way back when and I had to update my tool chest with 12 point sockets and wrenches when I went to the engine shop. Now I know why those nuts were preferred.
Fj
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