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  #1  
Old 04-26-2021, 08:12 AM
Robercom Robercom is offline
 
Join Date: Feb 2021
Location: alabama
Posts: 3
Default RV 8 Landing gear NUTS!

During inspection of my RV 8 landing gear I noticed one of the outer brackets was bent. I grounded the plane and ordered both the outer and inner brackets. The inner bracket was a challenge but the outer bracket is proving to be impossible. After a lot of headache and some verbal language I would never use around women or children I was successful in getting the bracket off. I got the new bracket in place and got both bolts through. Here is the issue... I was finally able to get the nut finger tight on the on the forward bolt. However, after 6 hours, bruised left forearm, bruised ribs from leaning over the side of the cockpit I finally gave up trying to get the back nut on.

I tried just using my hand and holding the nut with two fingers, I tried using painter's tape on the nut so I could put it in a socket and have it stay there while I tried to start it. I tried praying, pleading and offering my soul as sacrifice with no luck.

Looking for any advice from anyone who has changed these brackets after the build with wires, brake lines and fuel lines in the way. Frustrated...
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  #2  
Old 04-26-2021, 08:29 AM
Mike S's Avatar
Mike S Mike S is offline
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 16,052
Default Welcome to VAF

Brian, welcome to VAF

Pretty sure someone will come along with some help soon.

Good to have you aboard.
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VAF 909

Rv-10, N210LM.

Flying as of 12/4/2010

Phase 1 done, 2/4/2011

Sold after 240+ wonderful hours of flight.

"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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  #3  
Old 04-26-2021, 08:49 AM
PhatRV PhatRV is offline
 
Join Date: Mar 2018
Location: Buena Park, California
Posts: 563
Default

There are two AN3 bolts that may interfere with the nuts. They are shown in the cropped picture below. You have to loosen the AN3 nut so the bolt will retract to allow you the clearance to insert the nut from inside the gear tower. At least I think this is the problems from your description.

I also find it helpful to use Gorilla tape to secure the box wrench to the bolt head underneath the gear towers as I torque the nuts inside the tower. The tape will hold the box end to the nut to prevent the wrench from falling out. The long arm of the wrench will wedge against the landing gear structure to keep it from moving as torque is applied. I am not looking forward to retorque the nuts when I get my airplane flying. I also hope you are replacing the stock nut with the upgraded NAS nut as described somewhere in the RV8 forum

P.S. I find the open thread length of the original AN3 bolts is a bit long the long side which interferes with the access to the landing gear tower nut. I replaced one AN3 bolt with a slightly shorter one, still keeping 1 thread showing, to prevent the access problems you are experiencing
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RV8 standard build: Empennage 99% completed
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Last edited by PhatRV : 04-26-2021 at 08:52 AM. Reason: Added P.S.
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  #4  
Old 04-26-2021, 09:21 AM
Carl Froehlich's Avatar
Carl Froehlich Carl Froehlich is offline
 
Join Date: Dec 2007
Location: Dogwood Airpark (VA42)
Posts: 3,174
Default

Brian,

Just curious, are you using Van’s stock gear or the Grove gear?

If you don’t have a helper turning the bolt from the bottom while you hold the nut steady, you will continue to loose your religion.

If you missed it, here is a tread on making the miracle tool for tightening the inside the tower rear bolts.
https://vansairforce.net/community/s...d.php?t=191019

Carl
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  #5  
Old 04-26-2021, 10:46 AM
Robercom Robercom is offline
 
Join Date: Feb 2021
Location: alabama
Posts: 3
Default

I'm using the Vans stock brackets.

I believe I will try to back the bolt out and hold the nut over the hole while a helper gets it started from below. Anyway that's my next oh please make this work idea.

Is there any reason the torque cannot be achieved with the torque wrench on the bolt side while the nut is held in place? Would seem to me that would serve the same purpose and would be easier. I just made myself laugh considering the word easier in this situation. I should have said less than almost impossible.
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  #6  
Old 04-26-2021, 11:05 AM
Carl Froehlich's Avatar
Carl Froehlich Carl Froehlich is offline
 
Join Date: Dec 2007
Location: Dogwood Airpark (VA42)
Posts: 3,174
Default

Quote:
Originally Posted by Robercom View Post
I'm using the Vans stock brackets.SNIP

Is there any reason the torque cannot be achieved with the torque wrench on the bolt side while the nut is held in place? Would seem to me that would serve the same purpose and would be easier. I just made myself laugh considering the word easier in this situation. I should have said less than almost impossible.
You can do this, if you take into account the running torque of just the bolt. For example if it takes 10 ft-lb to turn the bolt with no nut (or nut loose), add this to your final torque setting. Here the old school beam and pointer torque wrenches come in handy - but I assume you can do the same with a clicker torque wrench.

Carl
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  #7  
Old 04-26-2021, 11:18 AM
scsmith scsmith is offline
 
Join Date: Jan 2008
Location: Ashland, OR
Posts: 2,945
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There has been lots of discussion and conversation about this.

First, PLEASE install the NAS1804 nuts, not NAS679 nuts. The NAS679 stamp-formed nuts are not sufficient for this application. Many examples of these being found loose. Our tests prove that they don't get loose by turning - they get loose by the nut expanding radially enough under tension that the threads actually leapfrog over to the next thread!
The primary reason for installing the better nuts is strength, but an added benefit is that they have smaller wrenching size, so easier to get a socket on the nut. Since the nuts are taller, it is desirable to buy bolts with longer threads - these are NAS6606 rather than NAS6206. The grip length stays the same. Although I say this is desirable, I don't believe it is strictly necessary. If you insist on have clear threads protrude beyond then nut, then yes, get the NAS6606. But with the NAS6206, there is sufficient thread engagement into the locking area of the nut, but perhaps not enough to protrude beyond the nut. So if you are a stickler for that, you will want the NAS6606.

Second, please read the installation instructions for the U-803 bracket. The faces that mate to the bottom of the fuselage are to be filed/ground down so that those faces do not touch when proper torque is applied. If I recall correctly, the prescribed gap is 0.030" or so - but the thing that matters is that they don't touch. This is done to assure that the bracket applies sufficient clamping pressure on the gear leg. If the faces of the bracket were to contact the fuselage prior to reaching proper torque, then adding more bolt torque does not clamp the bracket any tighter onto the gear leg. Unfortunately, this design does mean that the bracket does bend slightly at the proper torque. In a perfect world, it would be better if the faces did touch just at the proper torque, because this would prevent the bracket from bending, but in practice, you have no way to assure that the correct clamping pressure is applied to the gear leg if those faces touch.

Third, it is sort of OK to torque the bolt head rather than the nut, given the near impossibility of torquing the nuts unless the gear tower modification is done. But torquing the bolt head adds a lot of friction from turning the bolt in its hole, so one technique is to measure the friction torque with a torque wrench before drawing the bolt tight. This accounts for the bolt friction, and the locknut friction. Then add this to the specified torque value to get the torque needed to get proper value on the bolt. Even this is conservative, because as the bolt tightens, the friction increases AND the U-803 bracket bends slightly and tends to add more friction from binding on the bolt.

Many RV-8 builders were/are wise to do the gear tower modification to make working in this area quite a bit easier. In hindsight, I do so wish I had done it.
But the good news is that with the good NAS1804 nuts, you will not ever find that they have loosened. I have found that I can check the torque each year by putting a torque wrench on the bolt heads, and the nuts don't turn at the proper torque - I don't need to have a wrench on them.

Hope this helps. If you would like to learn more about this assembly, use the search capability. Look in particular for a very long thread called "breaking news" where we tested various nuts. Any additional questions, feel free to PM me.
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  #8  
Old 04-26-2021, 11:46 AM
Norman CYYJ Norman CYYJ is offline
 
Join Date: Feb 2005
Location: Victoria B.C.
Posts: 1,435
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After a lot of headache and some verbal language I would never use around women or children.

Need to be careful in your wording, that could be classified as a sexist remark. Lol
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  #9  
Old 04-27-2021, 05:39 AM
Robercom Robercom is offline
 
Join Date: Feb 2021
Location: alabama
Posts: 3
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Lots of good info.. Based on the other threads I just ordered the NAS6606-27 bolts and the NAS1804-6 nuts.

Next task will be to hire a small kid with long skinny arms and really strong hands.
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  #10  
Old 04-27-2021, 07:49 AM
werxcv01's Avatar
werxcv01 werxcv01 is offline
 
Join Date: Aug 2008
Location: Brandon, MS
Posts: 131
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Bruce Brielmaier is a VAF member who makes a clip to lock the bolt head in place in the gear tower so that the bolts can be installed from the top and one person can check the torque from the bottom at each annual condition inspection as recommended in the construction documents. I had to replace the bolts, nuts, and saddles last year before learning about these clips, but now have a set and plan to install them this year. We found if we jack up one wing, we could get enough play in the gear leg to make installation of the saddles, bolts and nuts a bit easier. Still, a long-armed, skinny helper would be useful.

Search for “Bloody annual - done” thread for a discussion about the clips.
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