Use of threadlocker - Kosher?

Tried to do a little research on if the use of threadlocker - Loctite Blue 242 or Permatex Medium Strength Blue is acceptable practice. I can't seem to find a clear answer.

I see that both RED and BLUE threadlock are called for under the RV-14's supply requirements on Page 03-04 of the Van's Manual.

I was considering using it on various screws and AN bolts an addition to torquing only as an added insurance measure. Obviously in more critical areas where a locknut or lockwire is used this is not necessary.

Thoughts?

Do not use around any plexiglas. The plexi will start cracking quickly if you do.

I used some red locktite on my wings tie downs. But I'm also an amateur. I just use a tiny bit, about as little as you can possibly use. I did a little research and didnt find much, but basically i figure it cant possibly hurt anything.

What Does that have to do with "Kosher?"

There are various substances from different manufacturers marked as "blue threadlocker" and "red threadlocker". They are not all created equal, although some are similar.

It would be best to first understand the particular location and conditions where you want to use a threadlocker, then contact a threadlocker manufacturer to determine what threadlocker might be appropriate for that application.

On any normal setup with a lock feature like a lock nut or a plate nut, I think it's unnecessary. Can be detrimental too if you damage a fastener or surrounding part during removal. It has it's place, but I sure wouldn't drip it on fairing screws or similar duty fasteners.

Aero_Octaveus said:

I was considering using it on various screws and AN bolts an addition to torquing only as an added insurance measure. Obviously in more critical areas where a locknut or lockwire is used this is not necessary.

Thoughts?

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Unless thread locker is specifically called for, I'd avoid it. The hardware has been proven sound over decades of use and literally millions of flight hours.

Every instance I've heard of in which a threaded fastener came loose has been due to failure to use appropriate hardware or to apply the proper torque in the first place. Instead, ensure that the correct hardware is used and torqued in accordance with AC43.13b. A little bit of nail polish or similar inspectors marking paint can then be applied when, and only when, you have verified that the hardware stack has been properly torqued.

My $0.02.

I use threadlocker on EVERY bolt or screw that is doesn't have a nut or platenut on the other end. There are not that many places to use it on a regular RV but on a -12, many of the engine bolts are blind. This is a holdover from building a 427 Cobra, which wants to shed parts like a dog shedding fleas! Be careful with the red stuff as that is meant for permanent connections but go ahead and use the blue stuff where needed. Ditto on keeping it far away from the plexi. You will craze it if you get any on it. Been there, done that, have a spare rear window for the -12 to prove it.

I would not use it as extra insurance where nuts and platenuts are present. It's not needed and just an extra pain in getting the parts apart. On platenuts, I actually lubricate them to make it a little easier to get screws out and to prevent galling and cross-threading.

My $.02.

"Kosher"

indicates approved, legitimate, correct etc in this usage....

I use 242 (blue) in addition to lock nuts in "critical" locations where loosening would have really undesirable consequences such as:

Control rod ends and jam nuts (includes flight and eng. controls & attach).
All flight control "Jesus" bolts/nuts.
Autopilot servo and attach hardware.

Probably some others but that's what came to me off the top of my head, you get the idea.

Make sure the thread locker is both Kosher and gluten-free.

I echo Walt's suggestion for using it on all jam nuts, for the control pushrods and hinge points for the elevators and rudder. It's just a little bit of extra insurance.

Yes, avoid all contact with plexi and don't even think about using it on a d-sub backshell housing. I tried this and one drop made that plastic explode!!

Rotax uses the stuff all over their engines. Magic stuff to keep fasteners on some vibrating pieces in race cars for me.

Just be careful when you have to check torque on some applications, will have to remove and clean threads. I would not use it everywhere but it certainly has its uses.