Thread sealant/indicator on bolts/nuts/plate nuts

I can tell it?s time to turn to the forums when I have been avoiding the project for a few weeks. Hoping you can help with question 2 of 2!

I have seen pictures on these forums and elsewhere that show a stripe of thick paint-like substance on fasteners, e.g. on the tip of a bolt where it comes through a plate nut, or where a nut goes over the tip of a bolt. I understand the concept of safety-wiring fasteners and believe this to be a separate but related practice. I see no mention of it in Van?s build manual. Is it?s purpose as I suppose, to indicate that a torqued bolt has not spun, and to help prevent them from spinning, used on fasteners with friction-safety like nylock nuts/deformed thread nut plates? What is this called?

The real question is to gage the wisdom of the crowd: does everyone do this, or is this an extra step many think a good idea and others eschew, like meticulously priming everything?

Thanks much,
Jeff

It's called Torque Seal, available from Aircraft Spruce. The idea is to apply a line along the threads, nut and whatever it bolts to so you can spot any tendency of the nut/bolt assembly to rotate or come loose.

I like to use it also, as you say, to mark fittings as a reminder that I've torqued them.

Here's a photo that shows both correct and incorrect usage (I've gone back and fixed the incorrect ones).

The Torque Seal on the rod end and jam nut of the aileron pushrod is correct. However, the pivot bolts on the bell crank are incorrect, as the bead of Torque Seal needs to extend down the nut, across the washer and onto the white powder coated metal.

I have been diligently doing this on my build, ONLY after the final assembly of the part and final torque has been verified by me.
I wake up some nights seeing a DAR breaking all the torque seals on the plane that I have so carefully installed!

Video

EAA has a video describing this: http://www.eaavideo.org/video.aspx?v=29739769001

I've also been told not to apply it to the threads on several occasions. Not sure how accuarate that is though.

Another reference: https://theleanwarehouse.wordpress.com/2012/08/01/application-of-torque-seal/

Keep in mind that ...

Torque seal can help you to remember which fasteners you torqued during assembly. It does NOT indicate that you still have proper torque after the aircraft has been operational for a period of time.

During an annual inspection, the presence of torque seal does not mean that the fastener is still properly torqued. The only way to check is to (as I learned from my brother) is to Put a Wrench on It.

I'm not saying I use a torque wrench on every fastener, every time, but I do check the tightness with a wrench on a regular basis.

Rick, a curiosity question-: Roughly how often do you find a fastener loose that came as a bit of a surprise to you when you use your "wrench on every nut" technique-?

I grab, touch, twist, feel, etc. with my hands/fingers, but usually don't put a wrench on things on a routine basis.

Willing to learn.............

PCHunt said:

Rick, a curiosity question-: Roughly how often do you find a fastener loose that came as a bit of a surprise to you when you use your "wrench on every nut" technique-?

I grab, touch, twist, feel, etc. with my hands/fingers, but usually don't put a wrench on things on a routine basis.

Willing to learn.............

Click to expand...

Pete, I find at least a few every year during the annual. Normally, it will only take maybe an 1/8th of a turn to tighten things up but there's been more than one time when it took a 1/2 turn or more to re-tighten a nut.

There's been more than one time that Walt asked me if I had checked such-and-such nut/bolt - which I had never thought to check before - and yes they needed to be tightened. At least as the years go on, I've gotten better at checking all the fasteners.

I'll put a wrench on the engine mount bolts without removing the cotter pins. I've only had to remove the cotter pins a couple of times to get them tight.

I check fuel line B-nuts at every oil change. It very rare that I find one that needs to be tightened but I feel better knowing that I checked.

Thanks, Rick. I'm gonna try to incorporate "wrench tests" into my inspections.

I did put a wrench on every nut on my first condition inspection of the -9A, there was a handful that needed just an eighth turn (mostly controls) and I did find one nut on the empennage attach points that was truly "loose" and needed a couple turns, which was shocking. None of the big nuts like engine mounts, wings, gear, plate nuts, wheels, or fuel/brake lines even budged. Of course I only flew 100 hours that year.