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Thread: Lock nuts or castle nuts with cotter pin

  1. #1
    Tim's Avatar
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    Lock nuts or castle nuts with cotter pin

    There was an old thread that talked about what to use on landing gear, can't find it, any help appreciated.

    Tim

  2. #2
    cubdriver2's Avatar
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    Anything that rotates should be cotter or safety wired, but.............................................al most ever gear bolt has a nylock on it.

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  3. #3
    40m's Avatar
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    Quote Originally Posted by cubdriver2 View Post
    Anything that rotates should be cotter or safety wired, but.............................................al most ever gear bolt has a nylock on it.

    Glenn
    expound on this a little bit more, please.

    From Genesis: "And God promised men that good and obedient wives would be
    found in all corners of the earth."

    Then he made the earth round... and He laughed and laughed and laughed!

  4. #4
    wireweinie's Avatar
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    If something normally rotates about the axis of the bolt, then it should have a castle nut and cotter pin to prevent the motion from, potentially, unscrewing the nut. Landing gear bolts do have a rotation around them, however it's a small amount and most everyone uses nylocs on them for convenience. Especially with aircraft that change from wheels to skis to floats a lot.

    Web
    Life's tough . . . wear a cup.

  5. #5
    40m's Avatar
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    Quote Originally Posted by wireweinie View Post
    If something normally rotates about the axis of the bolt, then it should have a castle nut and cotter pin to prevent the motion from, potentially, unscrewing the nut. Landing gear bolts do have a rotation around them, however it's a small amount and most everyone uses nylocs on them for convenience. Especially with aircraft that change from wheels to skis to floats a lot.

    Web
    Thanks Web.

    From Genesis: "And God promised men that good and obedient wives would be
    found in all corners of the earth."

    Then he made the earth round... and He laughed and laughed and laughed!

  6. #6

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    I believe the phrase is, "if the bolt is subject to rotation" , if I recall it was an FAA test answer almost 30 years ago.

    Now most Cubs, Pacers, later T crates, and my Tripacer have a tab to lock the head of the bolt against rotation. So as an IA if it has the tab, the bolt is not rotating, then the "fiber locking" nut may be used. God I sound like a lawyer. This keeps the bolt from rotating in the weld on fuse fitting and wearing this fitting out.


    Anyway, I use a minnie nut in this location, the six point all metal one, because of the ease of attaching a socket and it firmly engages the bolt threads every time.


    If you are going to use the fiber locking nut on your gear throw them away after about two uses; they are cheap enough. If it bothers you use a new one each time. If it's old and rusty and the insert is black and oily throw the damn things away.


    If in doubt use the castellated one with a cotter pin. Better yet consult with the A&P/IA who is signing off your aircraft maintenance or who has trained you to perform your "preventative maintenance"


    There are a number places I use a fiber locking nut where a castellated one had originally been used most of them being a function of the float to wheel change world I am involved with as well as one installation where a properly torqued and pinned castellated nut will work loose before the next 100 hour, a non rotation situation, and a fiber locker will not, but this is rare.


    Ok, one more thing to keep in mind: if it takes a cotter pin this does not mean the bolt is meant to be loos!!!!!!! The ball rod end, say at your throttle if it takes one, this bolt is meant to be tight. A hundred places on spam cans and Beavers with KSP4 bearings-tighten the dang bolt! I replace hundreds of dollars of fittings etc where the previous mechanic left the bolt loose thinking it needed to rotate and it hogged out the hole. The ball in the bearing rotates not the bolt.


    The little bug on your cub mixture and or carb heat... Ha ha ha haaa. Don't mix them up and pay attention, it could cost you your life. It takes a cotter pin, it needs to rotate in the hole, one is thick and one is thin, and that's all I'm saying.



    Rocket

    ps. say, where is MCS Mike on this one?
    pps. I do mostly DHCII and C100/200 float birds so YMMV.





  7. #7
    aktango58's Avatar
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    even if the bolt is held, the rotation can still push on the nut, and unscrew. So for me even with a tab you would require the cotter pin.


    But for me, yea, a fiber one because it comes off in three months anyway...
    I don't know where you've been me lad, but I see you won first Prize!

  8. #8

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    I don't see how, on those upper bolts. However, the shock strut bolts have no such anti-rotation flat, so the lock nut is probably inappropriate. In thousands of hours I have never seen one back off of a shock strut.

    On a Cub, the seriously important places for cotter pins are control bolts. I have seen them back off of tail brace wires, and if you use them there, a new one is really good advice.

  9. #9
    PerryB's Avatar
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    Quote Originally Posted by aktango58 View Post
    even if the bolt is held, the rotation can still push on the nut, and unscrew. So for me even with a tab you would require the cotter pin.
    Yeah, and some of us (not me of course) have landing gear bolts that see more rotation than others......
    After Monday and Tuesday, even the calendar says WTF !

  10. #10
    jnorris's Avatar
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    I stick with castle nuts and cotter pins on the gear bolts. I've seen plenty of them with self-locking nuts on them, but I stick to the castle nut/cotter pin setup. Easy to inspect, and more secure. I never worry about them.
    Joe

    Fortis Fortuna Adiuvat

  11. #11
    BC12D-4-85's Avatar
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    Ski cable tabs tend to twist or rotate under adjacent washers and nuts. All-metal high temp locking nuts are better than nylon inserts if the bolt threads are in good condition and not flattened from being driven through gear fittings. Cotter-keyed nuts are best.

    Pick your battles and enjoy flying.

    GAP

  12. #12
    irishfield's Avatar
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    I haven't lost a nut yet... but of course I've stayed married to the same woman for almost 35 years!

    Nylocks if you can... but won't pass an MDRA inspection if a new amateur built!

  13. #13
    www.SkupTech.com mike mcs repair's Avatar
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    Nylocks on gear bolts with tab.

    Very few places I use castle nuts any more. Old original technology

  14. #14
    www.SkupTech.com mike mcs repair's Avatar
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    You also gotta use common sense. Even if a nylock & bolt somehow rotates and loosens some, then it has lengthened and will not be bound and able to loosen any more.

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    Gordon Misch's Avatar
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    On the other hand, what does it take, - a minute? - to use a castle nut and cotter pin?
    Gordon

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  16. #16
    Steve Pierce's Avatar
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    I have some original Piper Landing Gear Bolt Kits. Nylon lock nuts on the gear to fuselage attach and cabane Vee attach. The shock struts top and bottom were drilled bolts, castle nuts and cotter pins since they rotate some on the end of the axle and cabane vee. J3s and early PA18s had castle nuts on everything but that was slowly changed over. Find lots of drilled bolts with nylon and in later models steel lock nuts in wings etc.
    Steve Pierce

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  17. #17
    Bill.Brine's Avatar
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    My other plane is a glider. Factory built in germany without a single castle nut. 100% nylocs.
    Looking in a new motor glider engine compartment you will not find a castle nut or safety wire. Lots of Nylocs.
    Are Castle nuts a remnant from a time past? or are German glider builders idiots?

  18. #18

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    The main reason I still use castellated nuts on the so call rotating parts (so called as in like on the gear legs, just a few degrees of movement, not a continuous rotation) is so that when my homebuilt is getting eyeballed by some self designated inspector at a fly in or on a ramp, he can't go "don't you know you need a castellated nut there?" I'd feel fine using nylocs there, but don't, old habits..etc

    One thing I picked up from the hang glider and ultralight aircraft time is using castellated nuts but no cotter pin, rather a circlip/safety pin/latch pin (pick the term) done right, makes for a as secure as a cotter pin install but lets you quickly and tool free remove it repeatably. That's how I do my gear nuts, castellated but no cotter pins, so quick and easy to get on and off and nobody gives me static over using nylocs.

  19. #19
    Cub junkie's Avatar
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    See what you started Tim.

  20. #20
    Tim's Avatar
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    Quote Originally Posted by Cub junkie View Post
    See what you started Tim.
    Ha, it made for interesting reading. I think I have my answer, do it anyway I want. I used castellated nuts and cotter keys. Thanks for all the replies guys

    Tim

  21. #21
    PerryB's Avatar
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    Quote Originally Posted by irishfield View Post
    I haven't lost a nut yet... but of course I've stayed married to the same woman for almost 35 years!
    I kind of expected something like this to surface, but certainly not from Wayne....... for shame!
    After Monday and Tuesday, even the calendar says WTF !

  22. #22
    cubdriver2's Avatar
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    Quote Originally Posted by Tim View Post
    Ha, it made for interesting reading. I think I have my answer, do it anyway I want. I used castellated nuts and cotter keys. Thanks for all the replies guys

    Tim
    Only because the bolts you removed were installed 20 + years ago and new ones will never be looked at again

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  23. #23
    Marty57's Avatar
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    What's the AN number or other number for the locking tab washers?
    Marty
    N367PS
    Psalm 36:7 "High and low among men find refuge in the shadow of His wing"
    www.marty2plus2.com

  24. #24
    Steve Pierce's Avatar
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    They are welded to the fuselage.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  25. #25
    Larry G's Avatar
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    Click image for larger version. 

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    I seen this picture somewhere else never seen a cotter pin done that way before. What is the proper way

  26. #26
    Cub junkie's Avatar
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    That's the artistic way.

  27. #27
    skywagon8a's Avatar
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    Quote Originally Posted by Larry G View Post
    Click image for larger version. 

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    I seen this picture somewhere else never seen a cotter pin done that way before. What is the proper way
    Check this video from Joe Norris.
    http://bcove.me/26k3f5qr
    N1PA

  28. #28
    Steve Pierce's Avatar
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    Service Bulletin on Cub Crafters CC18-180 to cotter pin the bottom of the sticks in the torque tube this way because the cotter pin hits the torque tube.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  29. #29
    jnorris's Avatar
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    Quote Originally Posted by skywagon8a View Post
    Check this video from Joe Norris.
    http://bcove.me/26k3f5qr
    What the heck does that guy know?????
    Joe

    Fortis Fortuna Adiuvat

  30. #30
    Steve Pierce's Avatar
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    Quote Originally Posted by jnorris View Post
    What the heck does that guy know?????
    When it is Rum thirty?
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  31. #31
    jnorris's Avatar
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    Quote Originally Posted by Steve Pierce View Post
    When it is Rum thirty?
    Drinking rum in the morning does not make you an alcoholic. It makes you a pirate!!
    Joe

    Fortis Fortuna Adiuvat

  32. #32
    wireweinie's Avatar
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    Quote Originally Posted by Larry G View Post
    Click image for larger version. 

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    I seen this picture somewhere else never seen a cotter pin done that way before. What is the proper way
    The 'proper' way is any way you can install the cotter pin, in which it does not rattle and it does not catch on other parts. All else is just gravy.

    Web
    Life's tough . . . wear a cup.

  33. #33
    aktango58's Avatar
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    Quote Originally Posted by wireweinie View Post
    The 'proper' way is any way you can install the cotter pin, in which it does not rattle and it does not catch on other parts. All else is just gravy.

    Web
    It is also nice when the next guy can reach into a space and back out without tearing his shirt, or drawing blood.
    I don't know where you've been me lad, but I see you won first Prize!

  34. #34

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    That one on the lower aileron horn has left lasting scars. Occasionally it is so bad my buddies say "you need stitches!"

  35. #35

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    Ok got to ask, saw a plane awhile ago with nyloc nuts on drilled bolts, is this legal/ok?

  36. #36
    wireweinie's Avatar
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    Quote Originally Posted by sburg58 View Post
    Ok got to ask, saw a plane awhile ago with nyloc nuts on drilled bolts, is this legal/ok?
    Legal. Might have just been the bolts that were available at the time.

    Web
    Life's tough . . . wear a cup.

  37. #37
    Steve Pierce's Avatar
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    Piper did it a lot. I guess they were using their stock of drilled bolts since early on everything was cotter keyed. Most were in shear. I have seen drilled bolts with lock nuts in tension break at the drilled hole.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  38. #38

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    Thanks I will pass that on to him, he was thinking they would need to be changed. I told him it was ok for experimental, then started thinking maybe it was not a safe or accepted use. Happy to see the experts weigh in.

  39. #39
    Eddie Foy's Avatar
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    Quote Originally Posted by sburg58 View Post
    Thanks I will pass that on to him, he was thinking they would need to be changed. I told him it was ok for experimental, then started thinking maybe it was not a safe or accepted use. Happy to see the experts weigh in.
    OK for experimental? It is either safe or it is not.

  40. #40
    AdirondackCub's Avatar
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    Agree with Glenn if it rotates, pin it. My gear has Nyloks

    MK
    Mark Keneston
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