AN fittings/ proper connection proceedure?

[Steve C]

Although I have fabricated many AN hoes/fitting assemblies I have never been quite sure of correct/ best proceedure for connection and tightening.

For example:

Should a small ammount of oil be applied to the seating surfaces or left dry, should some oil be applied to the threads before make up to aid in tightning, using AN wrenches how much torque/or better yet can one overtorque using AN wrenches, ect.

Appreciate replies.

Steve P2125

 

[Scott Calabro]

The last word on the subject;

AC 43.13-1B CHG 1 [Large AC. This includes Change 1.] Acceptable Methods, Techniques, and Practices - Aircraft Inspection and Repair

Chapter 9

Section 2

9-30

fig. 9-8

 

[Steve C]

Scott,

Great info but, did not adress my specific questions as to the actual assembly of one AN fitting to the other (unless I missed it).

See my post above...I know and have done a number of hose fabrications but, have the very basic questions as noted.

With you aircraft maintenance experience I'm sure you can answer me and set straight questions like..."best to lube or not lube the conical sealing surfaces of the AN's, lube or not the threads before assy and can one overtorque ising AN wrenches".

THANKS, Steve

 

[Scott Calabro]

Hi Steve,

Yes, lube the threads as shown in fig 9-8.

Tighten the nipple until you get a clearance of between .005 - .031" no real torque here so to speak.

If you want to lubricate the 37 deg flare and its "B" nut, go ahead and do so with the fluid that will be carried within the hose assy.

For fuel and mineral based fluid lines "Hylomar" works well also.

For torque data of the "B" nuts refer to table 9-2.

Or... 2 white knuckles!!!

Yes you can easily overtighten an AN fitting, especially when the tubing in question is a pipe flare and not a hose assy.

We don't use special wrenches on the aircraft tubing/hose assy's just plain old Snap-On or Bonney, etc.

"AN" fittings are almost obsolete on corporate jets now anyway.

Not sure what you mean when you say "AN wrench".

Cheers,
S

 

[Bill Musarra]

Steve,
Since Aeroquip is the main maker of the AN hoses I think you should defer to the power. They have an assembly instruction sheet that I have seen in the past but can't tell you where I got it. Might try the web site. Aeroquip makes an assembly lube that I have used in the past and present to assemble all sizes of hoses. These surfaces are aluminum and every effort should be taken to keep them form galling. If assembled dry and any large force is used to achive a seal the surface will weld to its counter part. The wrenches that Aeroquip sells will work to a certain degree. They can and do get beaten up rather easily as they are aluminum also. I think their objective is to not mar the surface when tighening. I think you will get just as good results from an adjustable wrench. You will need oposing wrenches when installing a fiting to a hose. Most of us don't have two sets, so your choice is to use a vise or adjustable wrench. Be sure to use electrical tape or something similar to keep the wire end from flaring out. It is a b***h to get it back where it should be. There is a new devise on the market. I haven't used it as it is rather expensive, and I wouder how it holds the hose without slipping. The key when installing the fitting to the hose is to not let the hose slip while tightening. Usually a felt tip pen will mark the hose and can be removed with OOPS or GOOF OFF. If it slips less than 1/8 inch you will propably be O K. Attaching the fitting to the hose should entail tightening the fitting to about a thumbnail thickness distance between the base(hose end) and the end of the fitting. Use lots of assembly lube when doing that so it will slide into the hose. I don't know of any torque numbers between the fitting and the hose end. I just tighten til I think it is sealed.
If you are using any used fittings off of Ebay, inspect the 37 degree end to make sure there are no flat spots. Circular lines around the 37 degree face are acceptable. That is where the fitting seats to the fitting. Any running fore and aft on that surface are a sign of wear or being dropped on to a rough surface, as in thrown. These will leak no matter how tight you turn the hose end.
If you are using anodised fittings, look for shiney aluminum on the treads This is where the anodised color is missing. If on the tips of the thread it will probably be O K. Otherwise I wouldn't trust it. The friction of the two aluminum surfaces will remove it. If lubricated with a slippery substance(assembly lube), at most, only the tip of the thread will be affected.
The question of how tight should you tighten. The hose end adapter usually has a hole in its base. If it is not tight enough, oil or whatever is in the line will come out. Once tight enough, it will stop. Hope this helps.

Bill

 

[Dave P]

The race teams around here use a product called Copaslip

 

[Randy V]

I've only got a couple of additions to what's been said;

1) Spend a few extra dollars and buy the highest quality AN Fittings. The only way that I will ever put a Russell or Earls fitting in one of my cars is if it is not available from Aeroquip. Yes - I will buy Aeroquip whenever possible as I feel they are of the highest quality. Same goes for the hoses.

2) Cutting of hose to length - I tape (duct tape) over the hose with two full wraps (tight) and then use a Cut-off wheel. I wash the hose out thoroughly after assembly to remove all traces of particles. Others use sharp chisels (I never really mastered it - but it does work). There are special cutters (Shears) that are made for this task - but I've never bought one.

3) Never use teflon thread tape or sealing compound on an AN fitting unless it's the end that is threaded as a PIPE fitting.

4) Always lubricate the hose using hose assembly oil or a bit of 30w motor oil (make certain this is washed out after complete assembly)

5) Always put just a drop or two of oil on the threads of a hose fitting so as to eliminate the potential of galling the threads when assembling.

6) Understand that AN fittings and braided hose do not have an infinite life span. It varies by conditions it's being used under and the contents being carried. For fuel lines (hoses) carrying gasoline - the rule of thumb is generally 5 years for a quality hose. I've seen some that start to weep after little more than a few months. It all goes back to the quality of the hoses and components.

All this said - I've made hundreds of hoses in this manner and they've all performed as expected with little to no drama involved.

Recently I happened upon a fellow using a new tool for assembling hose ends that intrigued me so much I tried it. Now I have a full set and I'll tell you right now, my hose assembly time is cut fully in half.

I used to always use a vice with aluminum jaws or minimally a vice with cardboard taped to the jaws to assemble the hose ends - until the discovery of the Koul Tool;

KOUL tools, LLC - Lake Havasu City, AZ

I still use the aluminum jaws for holding the fitting while turning the hose end on;

 

[chuck smith]

just another suggestion on AN hose. I have started using only Aeroquip Startlite Nomex hose instead of SS wrapped. It is much easier to work with, looks far more period correct and leaves no cuts on your hands. It is expensive however. I got most of mine from a company that sells overstock and used products. Racecityraceparts.com

 

[Randy V]

The only issues I'm aware of with the Starlite hoses / fittings is that they are not re-useable.. IE - if you get a hole or nick in a hose, you will throw away the hose and the fittings. It takes a special Starlite hose assembly rig to crimp the ends..

NASCAR and others are making great use of these hoses and fittings.

Can you use the Starlite hose with standard braided line fittings?

 

[Jack]

I have purchased many, many fittings and bits from racecityparts.com and have been pleased with them.

 

[Kirby Schrader]

I'd second Randy's techniques here. A friend gave me a set of Koul Tools for helping him install his EFI system and they are fantastic. They make the fitting make up so easy, you'll wonder why you didn't use them all your life.

I'll second the aluminum clamps, as well. Prior to using those, my AN fittings (especially the larger ones) looked pretty beat up with wrench marks.

The other thing I did was buy the anodized aluminum 'AN wrenches' to minimize damage to the anodizing on the fittings themselves.

FWIW,
Kirby

I've only got a couple of additions to what's been said;

1) Spend a few extra dollars and buy the highest quality AN Fittings. The only way that I will ever put a Russell or Earls fitting in one of my cars is if it is not available from Aeroquip. Yes - I will buy Aeroquip whenever possible as I feel they are of the highest quality. Same goes for the hoses.

2) Cutting of hose to length - I tape (duct tape) over the hose with two full wraps (tight) and then use a Cut-off wheel. I wash the hose out thoroughly after assembly to remove all traces of particles. Others use sharp chisels (I never really mastered it - but it does work). There are special cutters (Shears) that are made for this task - but I've never bought one.

3) Never use teflon thread tape or sealing compound on an AN fitting unless it's the end that is threaded as a PIPE fitting.

4) Always lubricate the hose using hose assembly oil or a bit of 30w motor oil (make certain this is washed out after complete assembly)

5) Always put just a drop or two of oil on the threads of a hose fitting so as to eliminate the potential of galling the threads when assembling.

6) Understand that AN fittings and braided hose do not have an infinite life span. It varies by conditions it's being used under and the contents being carried. For fuel lines (hoses) carrying gasoline - the rule of thumb is generally 5 years for a quality hose. I've seen some that start to weep after little more than a few months. It all goes back to the quality of the hoses and components.

All this said - I've made hundreds of hoses in this manner and they've all performed as expected with little to no drama involved.

Recently I happened upon a fellow using a new tool for assembling hose ends that intrigued me so much I tried it. Now I have a full set and I'll tell you right now, my hose assembly time is cut fully in half.

I used to always use a vice with aluminum jaws or minimally a vice with cardboard taped to the jaws to assemble the hose ends - until the discovery of the Koul Tool;

KOUL tools, LLC - Lake Havasu City, AZ

I still use the aluminum jaws for holding the fitting while turning the hose end on;

 

[Jack]

A wrap of duct tape aroung a standard adjustable wrench helps prevent marring the aluminum (on the cheap). Two sets of AN wrenches are usually needed, and the Koul Tools are the BEST! Strongly suggest aluminum vice jaw clamps...

Starlite hose requires crimping. Expensive, but very good..

 

[Steve C]

What a group of overachievers! LOL

I asked:

"Although I have fabricated many AN hoes/fitting assemblies I have never been quite sure of correct/ best proceedure for connection and tightening.

For example:

Should a small ammount of oil be applied to the seating surfaces or left dry, should some oil be applied to the threads before make up to aid in tightning, using AN wrenches how much torque/or better yet can one overtorque using AN wrenches, ect."

And you guys tell me how to build a space shuttle.

Only kidding. As usual the expertise available here is teriffic AND appreciated. This thread should be put in the "How To Section" for those not yet familiar with assembling AN hose assemblies.

Thanks again for all that responded.

Steve P2125

 

[James O'Sullivan]

If a lot of you guys are buying Aeroquip hoses do you buy them direct or through a distributor? I buy a lot of Aeroquip hoses and fittings from the US for aircraft, I usually buy the fittings from a few companies who manufacture AN fittings and sell at very competative prices such as Bailey Hydraulics and one of the best companies I deal with for assembles hoses is Speciality Hose. They may be worth looking up.

 

[Jack]

I purchase a lot of AN fittings from an outfit called Race Proven Parts. These are reusable fittings from NASCAR teams (used) at about half-price of new. No failures thusfar. Sometimes I'll purchase a made up length of hose w/fittings attached. Throw away the hose and keep the fittings. Much less expensive that way. I ALWAYS use new hose.

 

[J. Salmon]

This is a great thread, about a year too late. I have assembled countless hoses now, but none have been tested in battle. I have hose ends from Pegasus, Summit, Aeroquip, and a few from Russel's. I have used all braided stainless line, most of it from Summit. I didn't use a drop of oil in assembling anything, so I imagine any of mine that leak will be discarded. I am very careful not to over tighten the flare... you can always go back and snug it up.

I bought the AN wrenches from Summit, and they have been OK. The aluminum adjustable was cool for about 3 assemblies, and then it essentially died. If you are careful, a vice and regular adjustable works fine. I bet I over-torqued many of my fittings.

I'll have to do a report in the spring and let you know what happens when a monkey assembles a mixture of crap with little instruction. I honestly think I have assembled every line I need, so there is no sense in doing anything but waiting to see what doesn't work.

 

[Alex]

I just use the summit 'bolt' cutters to cut the hose, then aeropquip vice jaws to hold the fitting while I tighten.

I looked at the koul tools, but there's one problem with them (or maybe not, but I don't see how it would work) - how do you use it with 45* and 90* connections; seems like it will only work for straight connections.

 

[Jim Rosenthal]

Amen to that....although I did have the assistance of an experienced pair of hands in one of the guys in the shop coaching me through hose assembly. We have only done the radiator overflow tank lines etc; we still have to do some fuel lines and etc. I'll have additional opportunities to screw it up, no doubt.

 

[Jack]

Alex, a little assembly lube from Summit eases the assembly. I have been using the $20 cutters as well and they work fine. Saves a lot of time. The hose end "burrs"
are all bent slightly inward, allowing for much easier fittings assembly. Yes the Koul Tools work with 45 and 90 deg fittings, just can't get a full rotation of the "nut".

The Summit tool works well for the AQP rubber hoses too.

 

[Howard Jones]

I agree with a lot of the above. So my limited comments. Russel fittings should never be used for anything that might be mission critical, better yet try to think of something that is OK to fail. There is a very good reason they are the cheapest.

Earls on the other hand in my experience is as good as areoquip. The Summit or Jegs brand type are made by someone else for them. The question is who? See comment on Russel.

Heed the warning on using thread tape. Little pieces come off and end up in the worse possible places. Carb needle and seat, oil pressure gauges, worse.

Pay special attention to tube 90's and such. They crack and fail more offen than the solid kind. Also the swivel types are easy to work with but come at a price. The o-rings have been known to fail and spray oil all over the place. Really important things like oil filter, cooler lines, and HP fuel lines should avoid tube type swivel angle fittings. Use solid straight, 45's or 90's as much as possible. Also support the lines with clamps PROPERLY located to reduce the flex stress's as much as you can. Make the lines longer if necessary to avoid tight stressed turns.

And yes lube the fittings when you assemble them with clean 30 weight oil. I do and have never galled one yet.

I use a cut off wheel also. They do a nice clean (after cleanup of debris) cut.