safety wiring AN fitting nuts

brian · #1 12-18-2006, 01:00 PM

I was recently asked this question:

Why aren't flare tube fittings and hose fittings safety wired?

I have kinda wondered about this myself sometimes. I seem to vaguely recall that when I was a crew chief in the USAF in the early 70's that some AN fitting nuts were safetied, but I could be imagining it.

Does anyone have a good answer to this question?

thanks,
brian

jarhead · #2 12-18-2006, 05:51 PM

Good question... and I don't have an answer, either.

There were a couple safetywired AN fittings on the CH-53E that I remember. There were a handful on the J-34 engines that we tore down in A&P school. There's a couple on the S-76.

I have no idea why some are, and some aren't. I guess the argument could be made that the ones that are safetied are critical, but what about the other fittings in that same system (fuel, oil, hyd.) that aren't safetied? Are they somehow less critical???

Kevin Horton · #3 12-19-2006, 04:23 AM

Quote:

Originally Posted by jarhead

There were a couple safetywired AN fittings on the CH-53E that I remember. There were a handful on the J-34 engines that we tore down in A&P school. There's a couple on the S-76.

I have no idea why some are, and some aren't. I guess the argument could be made that the ones that are safetied are critical, but what about the other fittings in that same system (fuel, oil, hyd.) that aren't safetied? Are they somehow less critical???

I'm betting the ones that were safety wired were ones that had demonstrated through service history that they tended to loosen due to vibration.

Low Pass · #4 12-19-2006, 07:56 AM

Use some thread locking compound if you're concerned. I did a couple that way.

brian · #5 12-19-2006, 08:18 AM

Thanks for the replies. If anyone knows of an answer to this question, please do let me know. I was asked this question by a kid through the EAA, so I'd like to be able to provide an answer. It's a very good question, and I just don't know the answer.

brian

jarhead · #6 12-20-2006, 05:08 PM

Quote:

Originally Posted by Kevin Horton

I'm betting the ones that were safety wired were ones that had demonstrated through service history that they tended to loosen due to vibration.

I generally agree with that, but other fittings off the same component weren't safetied...

mbell · #7 12-20-2006, 08:12 PM

On my Yak-52 they are all safetied. Must be Mil-Spec for the Russians. Just replaced about 35 hoses and have the scars to prove it. On retracting landing gear and other parts that move it seems like a good idea, but in 35 years I have never seen a hose loose on a fitting.

Mike Bell