Oil Hose Leaking, "Weird Fitting"?

JonJay · #1 11-28-2011, 11:03 AM

Although this is on my Bucker, I wanted to post this here as it may be relevant to RV's, or any other aircraft.
A progressive oil leak developed from one hose feeding the Oil Cooler. I could not really tell if that is where the leak was coming from but I decided to build another hose and elliminate that as a possibility. I have always built my own hoses, Aeroquip brand or style. I did not build the hoses on my Bucker however.
Upon inspection of the hose, the Aeroquip fitting (not Aeroquip) looked odd from two stand points. The flare was larger than the Aeroquip and inside of the fitting smaller diameter. The really odd thing is the color of the fitting. Instead of the anodized shiny dark blue color, this fitting had a more matted robins egg color, or lighter blue. I did not notice this odd coloring as the fire sleeve and RTV covered much of it.
I could not tell if the flare angle was correct or not, but I changed out the 90deg. elbow into the cooler and discarded it and put a new fitting in along with the new hose.
Oil leak is now fixed.

I have not torn the hose or fitting apart yet to see if I can find any possible failure point but it appears normal from the outside.

Any thoughts?

Mike S · #2 11-28-2011, 11:43 AM

Automotive fitting with a 45* taper???

TS Flightlines · #3 11-28-2011, 12:35 PM

to see if it has a MS number on the collar, and the stem.
Tom

Rick_A · #4 11-28-2011, 03:17 PM

The older style AC fitting is 35 degrees and is Gray or Yellow. The most noticeable feature, as compared to an AN fitting is that the AC fitting does not have a shoulder between the flare and the threads. The body is also shorter overall.

JonJay · #5 11-28-2011, 04:01 PM

Quote:

Originally Posted by Rick_A

The older style AC fitting is 35 degrees and is Gray or Yellow. The most noticeable feature, as compared to an AN fitting is that the AC fitting does not have a shoulder between the flare and the threads. The body is also shorter overall.

Nailed it. Gray/Blue, I am color blind so I am sure that what you describe is it. There is no shoulder as you describe. Learn something new every day here.
I will tear it apart tonight and see if I can identify how it failed.

JonJay · #6 11-29-2011, 10:50 AM

Quote:

Originally Posted by JonJay

Nailed it. Gray/Blue, I am color blind so I am sure that what you describe is it. There is no shoulder as you describe. Learn something new every day here.
I will tear it apart tonight and see if I can identify how it failed.

Well, Rick, it isn't an AC fitting. It is an older Aeroquip. I am still mystified by the gray/blue color. The hose was leaking past the threaded part of the fitting that is inserted into the hose. According to Aeroquip web site, these compression fittings are better than the type that have the sharp edge that penetrates the inner hose jacket, however, that type was on the other end of the hose and did not leak. The hose is flexible and appears to still be plyable, good shape. I am throwing it out anyway.
For those making their own hoses or for the "hose makers" that visit hear, what is your opinion of the two types?

rocketbob · #7 11-29-2011, 11:16 AM

I have some NOS Aeroquip aircraft hose fittings that are the colors you describe. Probably 30 years old. They still have some paper tags on them. I have heard that anodized surfaces will fade with prolonged exposure to fluorescent lighting. Not sure if thats true or not.

Mike S · #8 11-29-2011, 11:18 AM

Sounds like time to give Tom a call at TS Flightlines.

JonJay · #9 11-29-2011, 11:21 AM

Quote:

Originally Posted by Mike S

Sounds like time to give Tom a call at TS Flightlines.

Just to be clear, the hoses are not that old, the fitting obviously was, but it is the only one of that type used, leading me to believe they where one fitting short and found one sitting around somewhere.
Still curious about the opinions on the "compression" type v.s. the "cutter" type.