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By Helix3
#398641
During a preflight of my year-old Sport 2 135 this past weekend, I noticed the bolt that goes through the hinge at the top of both uprights was sunk in the nylock nut. In other words, instead of 2 threads of the bolt screw showing above the nylock nut, the bolt was 2 threads *below* the nylock nut surface.

Looked at all the other WW wings in the LZ (T2C, Sport 2s) - all of their bolts showed 2 threads above the nylock nut.

Because the hinge keeps the bolt from turning, I'm worried the bolt might be stripped which caused it to sink in the nylock.

Took 1 upright off and rotated the hinge on the nylock nut side 360° while holding the bolt head steady with nose pliers so 1/2 of a bolt thread now shows above the nylock nut. Couldn't turn the hinge for another 360° because the hinge edge bumps up against the keel.

Is this sufficient for safe flying? There is a fly-in I'm attending at a site with notoriously rough air this weekend. Wondering if I need to disassemble the frame to inspect the bolt....

Has anyone heard of this happening to someone else + what caused it + how s/he solved it?

Thank you for your time.
User avatar
By Helix3
#398642
Sharing kind WW guru KH's response:

"It's very unlikely that the bolt or nut are stripped. The downtube fittings can't rotate more than half a turn relative to each other (unless things are taken apart) so there's no stripping mechanism. Also the nut doesn't really need to be a nylock for the same reason since the nylon part is there to keep a nut from spinning off. The bolt heads and nuts fit snugly into the fittings and sometimes bind before seating fully in the fittings and thus the threads may not emerge past the nylon. Not a problem in this particular application as long as the whole assembly doesn't rattle side-to-side. For peace of mind you could disconnect the downtube again and remove the nut completely to look at the threads then put it back together. Re-using the nylock nut in this case is perfectly ok."
User avatar
By red
#398645
Helix3 wrote:During a preflight of my year-old Sport 2 135 this past weekend, I noticed the bolt that goes through the hinge at the top of both uprights was sunk in the nylock nut. In other words, instead of 2 threads of the bolt screw showing above the nylock nut, the bolt was 2 threads *below* the nylock nut surface. Looked at all the other WW wings in the LZ (T2C, Sport 2s) - all of their bolts showed 2 threads above the nylock nut. Because the hinge keeps the bolt from turning, I'm worried the bolt might be stripped which caused it to sink in the nylock.
Is this sufficient for safe flying? There is a fly-in I'm attending at a site with notoriously rough air this weekend. Wondering if I need to disassemble the frame to inspect the bolt.... Thank you for your time.
Campers,

I hate it when "impossible" stuff appears on a preflight. Short answer: No, DO NOT FLY when there is ANY question about your hardware. Sorry if that keeps you on the ground for a few, but there are worse alternatives. The sky will still be there, when you and your gear are fully ready.

Stripped hardware is a possibility, and likely in this case. Threads can be stripped by force, misuse, cross-threading, or corrosion, not just by rotation. A new Nylock nut and new AN bolt will be the bare minimum that I recommend there, even if the old bolt appears to be perfect. Like I said, I do not like such mysteries. You may be able to loosen the keel fitting to install the new bolt and nut, rather than doing a complete disassembly there. DO NOT over-tighten any hardware on re-assembly; you do not want to crush (ovalize) the tubing. Make things as tight as they were when you started, but no tighter. NyLock nuts are not to be re-used, normally; all-metal lock nuts may be re-used, if they are undamaged.

You should know that with real (not counterfeit) AN hardware, the nut is designed to strip threads before the bolt does, because AN bolts may be scarcer than AN nuts, and the nuts are much cheaper than the bolts. Here (linked) is a lot more about aircraft hardware, which will explain the industry-standard AN bolt numbers that WW uses.

http://user.xmission.com/~red/AN%20Bolts%20Decoded.htm
User avatar
By dbotos
#398648
Helix3 wrote:Wondering if I need to disassemble the frame to inspect the bolt...
Better on the ground than in the air. Nut is a 5/16-24 AN365-524A ( $0.16 ), bolt is a 5/16-24 x 2-11/32 undrilled AN5-22A ( $1.18 ). Prices from Aircraft Spruce.

The CAD model in the Wills Wing manual shows the end of the bolt short of the end of the nut (see pg 59/79, ID # 16 and 33). Not sure if that's intentional or not. The next two longer AN5 bolts are 1/8" and 1/4" longer than the one listed, so it's not like you'd be making a major jump up in length and having excessive thread stickout.

http://willswing.com/wp-content/uploads ... y_2009.pdf
User avatar
By Helix3
#398651
red - Out of all the non-instructor hg mentors out there, you probably spend the most time answering questions + generously sharing your knowledge. Another round of drinks on me next time I'm in town (despite the 2.5% Mormon rule).

dbotos - Never would have found the parts without your help. Putting in an order today. Bless your heart for saving me from dealer prices. If you're ever in NorCal and need a glider, you can borrow one of mine. How did you figure out the 2-11/32 Nominal Length from the manual?
User avatar
By dbotos
#398652
Helix3 wrote:dbotos - Never would have found the parts without your help. Putting in an order today. Bless your heart for saving me from dealer prices. If you're ever in NorCal and need a glider, you can borrow one of mine. How did you figure out the 2-11/32 Nominal Length from the manual?
I'll have to keep that offer in mind if I ever finish up my H2. :mrgreen:

Length is in the congugation of the part number:

AN5 = 5/16-24 thread size
-22 = 2-11/32 length for AN5
A = undrilled

The full eye chart that includes AN5 is here (click orange Download File button to see pdf):

http://everyspec.com/AN-SPECS/AN100-AN9 ... V-12_6281/
User avatar
By klh
#398657
Attached is an image of the Litestream Control Bar Apex bolt and nut. As can be seen, the fittings hold the sides of the nut and the head of the bolt such that they cannot rotate relative to each other more than 1/4 of a turn or so as long as the cables and such are attached and the downtubes are intact.

The Nylon material in the Nyloc nut is not doing a thing except maybe keeping the fitting from rotating when one is replacing a downtube. If the end of the bolt is into the nylon then the threads are past the metal threads of the nut and the pull strength is full. The bolt is in a shear load anyway.

Good Flying,,
Ken Howells
Attachments
litestreamApexBoltAndNut.jpg
litestreamApexBoltAndNut.jpg (482.1 KiB) Viewed 1490 times
User avatar
By dbotos
#398660
Ken,

To remove that bolt and nut for inspection, would it go something like this?

0) Glider in bag, zipper facing up. Open up bag to access control bar portion. Keep downtubes parallel to ground.

1) Remove screw holding left downtube to elbow (where the elbow is the piece that has the nut captured).

2) Pull left downtube away a few inches.

3) Rotate elbow and nut together to remove from bolt.

4) Slide bolt out once elbow and nut are off.

David
User avatar
By klh
#398661
David,

Yes, that's pretty much it. I lift the downtubes out and lay them out to each side, perpendicular to the keel. There's a 5/16" nut on the end of the bolt that secures the elbow to the end cap and you need a small open end wrench to hold the nut in the slot. Also there are thin plastic washers between the elbows and the mounting bracket - don't lose them in the sail ;)
User avatar
By red
#398662
klh wrote:Attached is an image of the Litestream Control Bar Apex bolt and nut. As can be seen, the fittings hold the sides of the nut and the head of the bolt such that they cannot rotate relative to each other more than 1/4 of a turn or so as long as the cables and such are attached and the downtubes are intact. The Nylon material in the Nyloc nut is not doing a thing except maybe keeping the fitting from rotating when one is replacing a downtube. If the end of the bolt is into the nylon then the threads are past the metal threads of the nut and the pull strength is full. The bolt is in a shear load anyway. Good Flying,,
Ken Howells
Campers,

Excellent pix! This is one of those "non-normal" applications where a NyLock nut could be re-used, because the Nylon locking feature is not needed by the design. The Sport2 has a very similar design concept, in the same place. No "free standing" NyLock nut should ever be re-used, normally. These particular designs are two special cases, which do not relate to most real-world applications of NyLock nuts. Again, all-metal locking nuts may be re-used, if not damaged.

:mrgreen:
User avatar
By dbotos
#398663
Ken,

That is a clever design. I'll have to remember about the washers if I ever take that joint apart.

David
User avatar
By peanuts
#398682
If anyone out there ever decides to replace a bolt on their dangle kite with a longer one, check to see that it can't do harm to other pieces, tubes,etc when wing is folded for bagging.
User avatar
By Tormod
#398841
dbotos wrote:
Helix3 wrote:dbotos - Never would have found the parts without your help. Putting in an order today. Bless your heart for saving me from dealer prices. If you're ever in NorCal and need a glider, you can borrow one of mine. How did you figure out the 2-11/32 Nominal Length from the manual?
I'll have to keep that offer in mind if I ever finish up my H2. :mrgreen:

Length is in the congugation of the part number:

AN5 = 5/16-24 thread size
-22 = 2-11/32 length for AN5
A = undrilled

The full eye chart that includes AN5 is here (click orange Download File button to see pdf):

http://everyspec.com/AN-SPECS/AN100-AN9 ... V-12_6281/
Isn't the lenght in 1/8" inch steps? The first number defines the lenght in whole inches, then you multiply the next with 1/8 and add that.

A AN5-22(A) bolt would then be 2 and 1/4" long measured from under the head.
User avatar
By dbotos
#398844
The dash number (the number after the "-") is just referring to a specific row in the table. Depending on the thread size, the same dash number could be a completely different length. For example, look at the dash 22 row on page 2:

AN3-22 is 2-9/32" long
AN4-22 is 2-9/32" long

AN5-22 is 2-11/32" long

AN6-22 is 2-21/64" long

AN7-22 is 2-11/32" long
AN8-22 is 2-11/32" long

AN9-22 is 2-13/32" long

Be careful on the step sizes too. Sometimes the steps are smaller when they're really short. For example, AN3-3 to AN3-4 is only a 1/16" step, but then starts going into 1/8" steps after that.

The short answer is "always refer to the spec / tables". :wink:
By Carl
#398846
It appears to me,from a mechanical standpoint,that particular bolt is intentionally short in order to prevent abrasions- a location that a cap nut could be used in.
Like it has been said the securing feature of the nylock is not being employed here.
I believe a lot of thought was put into the decision to go this route

Thanks for the AN bolt chart and information!
I find it very interesting and useful
Another bit of knowledge that will keep me flying more safely
Thanks again
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