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lower q2 wires washers

wexfordair

Student Pilot
#1
Anyone know why they use 5/16 washers here at the upright? The bolt is 6mm.
They are very sloppy and seem like they were the only washers available at design stage to prevent the swaged wire slipping off. Or is there another reason I'm missing?
 

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Dave Morton

Student Pilot
#2
Primarily it is to stop the wire from leaving the bolt but they should be a little sloppy so any movement is allowed to move as opposed to the wire where it enters the swage from stressing should the bolts be completely tightened.
The washers are cheap and rust very quickly so I use a nylon washer which is strong enough for the job and eliminates rusting.
 

Dave Morton

Student Pilot
#4
I use both nylon inside and out, you could if wanting extra security add a small metal washer between the nylon and nut but you may have to increase the bolt length to achieve the correct amount of threads showing through the nyloc of the nut.
 

Andy Dixon

Cross Country Pilot
#5
I used aviation grade stainless steel washers, same rusting problem, different solution
N.B. stainless steel washers are usually thinner than the original steel washers, and therefore not as strong,so buy wisely or double up, but as Dave says ....make sure there is enough spare bolt sticking out of the nylon locknut.
 
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#6
Maybe merit in both ways, nylon on the inside to avoid scoring the upright, and stainless on the outside to give piece of mind.. I still don't get why they went for 5/16 instead of 1/4
 

Andy Dixon

Cross Country Pilot
#9
I’ve just done a list of every nut and bolt for a Quik wing strip tomorrow, 1/3 of the bolts are metric....1/3 unf imperial..... and a 1/3 A.N. Bolts. And 6 of the bolts are high tensile 12.3,And the rest are normal 8.8
you work that one out because it still amazes me 19 years later. It all works well and the wings don’t fall out of the sky
 
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#10
It's a funny one alright. I was thinking the other day that it could be something to do with having the right length of bolt and ideal ratio of thread vs shank and be able to get a couple of washers and swaged wires onto each end. It does work quite well and you end up with just the right amount of thread sticking out!
 
#11
Standard bolts have a specific length of thread irrespective of how long they are. From memory the thread length is 4x the diameter so as an example, for a 40mm long or less M10 bolt there would be no plain shank, just thread. For a 120mm long M10 bolt there would be 80mm of plain shank and 40mm of thread on the end. Actual dimensions depend on the spec they are made to, e.g. DIN, BS, ANSI etc.
Generally, you shouldn't have any threaded part of the bolt in the hole when a bolt is used in shear, as the threaded section is weaker than the plain shank and may also damage the inside of the hole. Also, there should be a minimum of 2 full threads exposed when the nut is tightened onto the bolt.
 
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#12
I recently changed my roll bearing on the Quik, (your trike hangs from this bearing) the bolt I removed holding the bearing in place was threaded its full shank so totally unsuitable for the job, this meant that it came from P&M like this which is shocking, but knowing P&M perhaps not that shocking...
 
#13
That may be classed as a set-screw which is in effect a fully threaded bolt irrespective of length. They are usually used to locate a part in place or provide adjustment rather than take loads, so could be ok depending on what it is doing.
 
#14
M6x80 cap head bolt.
Should only have threads for about an inch. Mine was fine when I stripped it over xmas. It should now have a nut on the end by the way. Threaded all the way would be a no no as the twisting forces would work like a hacksaw on the keel and it's sheer strength would be compromised as well, even though it doesn't take huge loads unless the Bush has swollen
 

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#15
Yes, that bolt is to locate the nylon roll-bearing on the keel tube and stop it rotating. I think it also allows changing the hang-point position on some wings. I believe there was a mod or other instruction on certain wings some years ago about that bolt, maybe to add the nut. I also have a feeling it was a special bolt with a cut-down thread-length so it didn't protrude out of the hole in the roll-bearing, but it shouldn't have any thread in contact with the keel-tube when correctly assembled.
 
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#16
M6x80 cap head bolt.
Should only have threads for about an inch. Mine was fine when I stripped it over xmas. It should now have a nut on the end by the way. Threaded all the way would be a no no as the twisting forces would work like a hacksaw on the keel and it's sheer strength would be compromised as well, even though it doesn't take huge loads unless the Bush has swollen
The nut was ok as in not protruding the bearing, the bearing itself was slightly swollen but still allowed the hang bracket to rotate by hand with the wing removed and was picked up during a wing strip early last year and most importantly there was no elongating of the hole by the threads of the bolt.
 

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