Castle Nut Replacement?

[Sven]

Does anyone know if castle nuts need to be replaced if they have been removed? The ones I am looking at removing seem to be in excellent shape. I just don't want to mess with something if I don't need to.

Thanks,

Sven

[Mcstealth]

No, just the cotter pin that should be with the castellated nut.

[KSMooniac]

that was me above, not Mcstealth...

[jetmech1972]

The castlenut does not have to be replaced as long as the threads are good, however the cotter pin must be replaced.

[Sven]

These are the kind without cotter pins. Maybe they're not called castle nuts but they look like them.

[Sven]

Looking at Aircraft Spruce online, it may be called a stop nut.

[jetmech1972]

Does the nut have plastic or colored material inside the upper third of the nut?  If so, it's a fiber locking nut.  They may be reused once or twice provided there is resistence once the bolt begins to pass through when tightening, otherwise discard.  Note there should be 2-3 threads showing after torqueing nut.

[Sven]

It does not have any nylon in it. It's all metal. It looks like this:

[Kwixdraw]

That would be a metal locknut. I don't happen to remember the AN #.( Working on my A&P now.)  Get a copy of AC 43.13 approved methods and techniques of repair and you will have the answers to most any of these questions that pop up. Around $19 from Sportys or Spruce. You should have a copy around when doing any work on your bird along with the service manual.

[carusoam]

Advice from the assistant to the mechanic......

The all metal lock nuts are reusable.  (My mechanic would re-use them).  They are also easy enough to replace.  Low cost and available from Spruce and Specialty.  (I usually keep a few of the most common on hand and pass new ones to my mechanic)

You can usually get a feel for their health while tightenening them on.  The locking part  will provide extra resistance compared to the first part of the nut.  If you do not feel the extra resistance.....strongly consider replacement....

The all metal lock nuts are usually used in places where the temperature can be high.  The nylon or "fiber" lock nuts could have their locking mechanism melt in these high temperature environments. 

Nylon lock nuts do come in a high temperature version.  They are usually color coded (white, green or red)

I would stay with the recommended part from the parts manual for your bird.  On 40 year old planes, there may have been substitutions.

Disclaimer: Always check with your mechanic (not the assistant for further guidance)

-a-

[rogerl]

Quote: Kwixdraw

That would be a metal locknut. I don't happen to remember the AN #.( Working on my A&P now.)  Get a copy of AC 43.13 approved methods and techniques of repair and you will have the answers to most any of these questions that pop up. Around $19 from Sportys or Spruce. You should have a copy around when doing any work on your bird along with the service manual.

[jetmech1972]

Great point Carusoam, Always follow maintenance manual and illustrated parts catalog for correct hardware and installation.  AC 46.13 is a great book for general repairs, for proper hardware use, installation, and torque specs; and can be referenced when signing a logbook.

If the lock nut came from a high temp area I would consider replacing it even if tension was felt.

side note: Marvel mystery oil is great for loosening seized bolts and nuts!  Works better than brands like mouse milk, or WD40 and can be found in any autoparts store.  We use this all the time in the UAL jet shop. 

[Sven]

Thanks for all the advice. I really appreciate the help. The link to the FAA maintenance manual is a big help. It has a section devoted to the identification of a lot of hardware. Part of my problem, as evident in this thread, is that I don't know what things are called. This should help me feel a bit more smarterer.

Sven

[Alan Fox]

That is a tourque nut and does not have to be replaced if it still has resistance , I do however replace all the hardware when I work on my plane.. (my a&p thinks I am nuts(no pun intended))

[N201MKTurbo]

With regard to the nuts, if I cannot spin them on with my fingers then they are still good.