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  #71  
Old 10-10-2012, 09:21 PM
NASA515 NASA515 is offline
 
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Quote:
Originally Posted by rvbuilder2002 View Post
My thought is....

Changing to a close tolerance fastener to fix a problem caused by the original fasteners not being tight, is not a good choice, and the fact that these bolts for the most part are loaded in tension, not in shear (unlike the majority of fasteners in an aircraft).
I'd have to dig out my engineering texts and - zero in the def of "close tolerance", but these bolts - especially the AN6-23A - do not exactly slide in! How about a lot of pounding with a heavy hammer - a lot. I even considered packing the bolts in dry ice.

Bob Bogash
N737G
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  #72  
Old 10-10-2012, 10:28 PM
RFSchaller RFSchaller is offline
 
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If the bolts are that tight I wonder if they are creating a hoop stress on the hole contributing to crack initiation around the hole.
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  #73  
Old 10-11-2012, 04:59 AM
BigJohn BigJohn is offline
 
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Originally Posted by RFSchaller View Post
If the bolts are that tight I wonder if they are creating a hoop stress on the hole contributing to crack initiation around the hole.
The AN6 bolts are the inner center bolts. Haven't heard of any cracks at that location.
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  #74  
Old 10-11-2012, 06:14 AM
Peterk Peterk is offline
 
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Quote:
Originally Posted by BigJohn View Post
The AN6 bolts are the inner center bolts. Haven't heard of any cracks at that location.
And Nasa's is the first I've heard of that didn't "slide in". I pretty much went by the rule, "if it doesn't fit, you've done something wrong."
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  #75  
Old 10-11-2012, 07:41 AM
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Tony_T Tony_T is offline
 
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Quote:
Originally Posted by tim walter View Post
I'm not sure that will help, the self aligning washers are used when the two mating surfaces are flat but not parallel.
The problem in our case is a "step" i.e. "not flat" surface.

all 4 of my nut locations have a significant step, I'm hoping Vans will come out with a further updated SB with instructions on what to do about these steps.
Van's is well aware of the "step" as myself and others have sent photos. Their Landing Gear Analysis publication indicates that they are working on an engineered solution, although it is not specific yet how they are going to do it. Also, in feedback to me from my photo they indicated that there will be "update parts" and the step in the center section will become a "non issue".

At this point, they have indicated that those with flying aircraft should do the SB as directed in order to prevent any damage. Those with damage should wait for the engineered solutions.

I think it can be safely assumed that hardware will be offered that will address the "step" in the center section.

Tony
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  #76  
Old 10-11-2012, 11:02 AM
NASA515 NASA515 is offline
 
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Quote:
Originally Posted by Peterk View Post
And Nasa's is the first I've heard of that didn't "slide in". I pretty much went by the rule, "if it doesn't fit, you've done something wrong."
Well, the SB does describe seating the bolt with a hammer, and using a wood block to protect the head.

I can tell you I destroyed several wood blocks, and anticipating another bolt change, have laid in a supply of red oak flooring strips for the next time around.

It could be I have a problem, but they sure didn't just slide in!

Bob Bogash
N737G
Waiting for the "Final Solution"
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  #77  
Old 10-11-2012, 11:41 AM
tim walter tim walter is offline
 
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Quote:
Originally Posted by NASA515 View Post
Well, the SB does describe seating the bolt with a hammer, and using a wood block to protect the head.

I can tell you I destroyed several wood blocks, and anticipating another bolt change, have laid in a supply of red oak flooring strips for the next time around.

It could be I have a problem, but they sure didn't just slide in!

Bob Bogash
N737G
Waiting for the "Final Solution"
I don't think they should have been THAT tight.
one of mine went in with a single rubber mallet tap
the other took a pretty good pounding with the soft mallet, but not anything that would have broken an oak plank !
(I'm talking about the AN6 through bolt)
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  #78  
Old 10-12-2012, 04:16 PM
rgmwa rgmwa is offline
 
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Default Gear analysis updated

Addendum issued:

http://vansaircraft.com/images/open/...pdate10-12.pdf
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  #79  
Old 10-13-2012, 08:37 AM
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JerryG150 JerryG150 is offline
 
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Default I'm not an aeronautical engineer ...

I'm not an aeronautical engineer ... I'm not even a good builder ... that said, it seems to me the landing gear "problem" could have been prevented by beating all the landing gear bolts and brackets with a hunk of wood and a hammer to be sure as heck they were properly seated and then torque the devil out of all the nuts and bolts (extra torque for bolt TIGHTNESS in hole and nut torque)! When the next revision for Section 35-3 is published ... it must say much, much more than "when the leg is properly positioned, tighten all hardware" as it states in revision 10-5-11.

Remember, I'm not an aeronautical engineer ... I'm not even a good builder ... but ...
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  #80  
Old 10-13-2012, 06:21 PM
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MacPara MacPara is offline
 
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Quote:
Originally Posted by NASA515 View Post
Well, the SB does describe seating the bolt with a hammer, and using a wood block to protect the head.

I can tell you I destroyed several wood blocks, and anticipating another bolt change, have laid in a supply of red oak flooring strips for the next time around.

It could be I have a problem, but they sure didn't just slide in!

Bob Bogash
N737G
Waiting for the "Final Solution"
You were not the only one having this problem. My AN6 bolts didn't split wooden blocks but I needed a hammer to get them seated in those holes and it took quite a while. The smaller ones went in ok.
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