Clocking versus Torque

Several of the FWF fittings on the lycoming and firewall are often 823 or 822 (45/90 degree fittings). Often there is a specific clocking that is needed to accomodate a hose.

Often it is impossible to get the fitting within the recommended torque range AND proper clocking. The approach I've taken is to get the fitting as close to the recommended torque and then adjust for clocking - something less torque, sometimes more. I am using Loctite 567 that should also help with any thread leakage.

Am I asking for trouble by not ensuring at least the minimum torque on these fittings even with a thread sealant?

What is the best way to go about fitting that needs a minimum torque and clocking to work?

I worried like crazy about this issue, and ended up taking two approaches:
1. If a different fitting or hose length was clearly going to made a huge difference, I made the change
2. If not, I adjusted the fitting to the required clocking. Sometimes this required loosening a fitting installed by the engine builder. I talked to Bart at Aerosport about this and he said it was fine within reason.

I had no leaks and no scary hose routings once I was done.
Good luck - Paul

http://www.surpluscenter.com/techhelp/NPT.pdf. "Finger tight" is not an exact value and there is some variation in manufacture, so you may not get 3 turns after "finger tight" but you should get enough to get any clocking you need. Due to the nature of NPT fittings, torquing will not generally improve the seal, so there's no need to overdo it. Use sealant always.

Truly, think of the torque as a maximum rather than a minimum. In fact, the instructions for the FT-60 state specifically a torque value or number of turns past finger tight whichever comes first, or you risk cracking the housing the fitting goes into. On the brake master cylinders or engine fittings, I have had no problem clocking between 2 and 3 turns - no leaks and no tendency to back out.

PS - as the link states, never loosen a fitting to get the desired clocking. If you must do this, remove the fitting and reinstall from scratch.

I had this situation with the top oil cooler fitting. Was one of those situations where I wasn't sure i could get tbe 45/90 degree fitting one more revolution. It was tight, but not THAT tight. So i attached the hose and I'm flying.

You know that oil on the bottom cowling after the early flights? Guess where it's coming from? I'm going to try some other fittings and see if they clock better but I'm finding that in these fittings, tight matters.

aviation form a gasket

When I was a mechanic, we used to use Aviation Form-a gasket from Locktite on these fittings. I still have a tube from 30 years ago. I am not sure what the current FAA approved material is, but with sealant, I never had a problem clocking the fitting and having it tight enough not to leak. If you go past, it is better to remove the fitting, add a little bit more sealant, and try again. As mentioned above, I never "slightly loosen" a fitting to make the clock right. And I always keep the sealant off the first 2 threads per the FAA mechanics bible. JMHO

I ran into this also and my solution was to install straight NPT fittings wherever possible and have the hose made with a 45 or 90 deg flared fitting. If you need an angled fitting on both ends of the hose, it requires you to figure out the clocking of the fittings.

Taper/pipe thread fittings need to be TIGHT, I have found many folks under-torque them and they leak.

If you can't get the clocking right try another fitting, there is enough variation in them that many times a different fitting will give the angle you need.

Loctite 272 or 242 works really well in that type of situation. Make sure the threads are really clean and apply the thread locker/sealant and tighten then fitting as much as you can without going past the clock position you want it at and the Loctite will do the rest. No leaks and the fitting will be tight after the Loctite cures. Just to see how well this works, take a bolt and nut and assemble by hand with the Loctite on the threads. Wait an hour and now try to unscrew the nut off the bolt. Now you know why the semi tight threads in the pipe fitting are tight and non- leaking after using that product. It is wonderful stuff!
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."

Vacuum systems?

Any special concerns or precautions for vacuum systems?

Bob Axsom

Bob Axsom said:

Any special concerns or precautions for vacuum systems?

Bob Axsom

Click to expand...

No thead sealant on vacuum systems, lubricate the treads with silicone and install.