i'm probably going to get in trouble for doing this,
but I emailed ANfittings.com, with this question:
'Are the fittings you have class 2 or class 3 threads?'
Their reply:
Hello,
Thank you for your inquiry. We are the manufacturer of this product although production occurs overseas. They are standard AN threads with the specifications listed here:
https://en.wikipedia.org/wiki/AN_thread
Thanks,
(name ommited by me)
Customer Service
AN Fittings Direct, Inc.
www.anfittingsdirect.com
[email protected]
So---since there is a big discussion of AN grade, or not AN grade, they seemed to sidestep the question by referring to the definition of AN Thread, and its comparison to JIC, instead of saying whether or not theirs was a class 2 or class 3 thread. Also their statement that "production occurs overseas" isnt a surprise to me, based on the pricing of the fittings.
I am NOT knocking companies that produce components overseas that use MIL SPEC standards, including the prints, the materials, the manufacturing procedures (like thread rolling for 3A thread), and the quality control inspections with the appropriate certifications and documentation. I am not comfortable with companies the say this is a 'AN fitting' when it isnt. Manufactured to a MIL-SPEC drawing is different than to MIL-SPEC. What materials were used?
If you REALLY want to dig into this, request the MILL report on the materials that were used to manufacture the fittings. Then get an independent lab to verify that report. Then examine very carefully the machining, the threads and the common dimensions of the fitting. Then, in the case of a teflon hose end, the Nut will probably be Mil-Spec, the body and OD and ID will 'probably' be within a range margin. The crimp area, or the screw collar area will be different, because thats where the individual company that has the manufacturing rights (lets say Eaton Aeroquip, Parker Stratoflex, Smiths-Titeflex, and some others including Earl's Performance) differs from their competitor. They are certifying that the materials, the connection part of the fittings meet the "AN" Mil Specification for that fitting. NOT necessarily the way the hose attaches to the fitting. Aeroquip's design is different than Stratoflex, which is similar but different than Titeflex, that is also different than Earl's. Why? copyright or patent infringement stuff.
So---with all that, does Stratoflex, Aeroquip, Titeflex, Earls, etc meet AN Spec? They certify they do. Does Earls; they say AN fittings, so they say ( I assume) that some part DOES meet the AN spec. Others---um--maybe in the name 'AN fitting' but maybe not AN grade as per the Mil Spec. It may look like it, smell like it, assemble like it, resemble a "certified" fitting by the way the components integrate, (like the brass olive over the liner, under the braid, squeezing onto the stem design that was pictured in this thread.) But, calling it an AN fitting with a brass olive isnt exactly right. Aeroquip's 'certified' design has a stainless olive. And class 3 threads on the stem and collar, not class 2. AND--swivel stems--Aeroquips design has the stem is part of the body of the fitting, with the threaded collar and a male threaded nut to capture the olive to the hose and stem. It 'can' rotate during assembly if indexing is necessary BEFORE final assembly. NOT a live swivel that is sealed by an O'Ring, and lock wire that not only 'can' rotate after assembly, 'can' leak under not nominal conditions. A Mil SPec live swivel has redundant seals around ball or needle bearings to allow the fitting to rotate.
So---when talking about "AN" or not 'AN" is a gray area. IF the fitting is stamped 'AN" or has a MilSpec number on it, it IS a true certified fitting. And, somewhere there is the traceability information on that fitting. IF there isnt, it may be manufactured to the PRINT of an AN or MilSpec fitting, but may NOT meet all the criteria. Steve and I just spent the better part of 2 years dealing with this.
I certainly dont mean to stomp on anyone, and if I have I certainly didnt mean to. We build experimentals because they give us some latitude in things we can do. What a particular builder puts on his or her aircraft is up to them, under 'suggested' guidelines, either published ones, or from similar applications. We all want to use the best materials we can, given the conditions we operate under. For most of us its a budget. There are many applications where a builder has a choice whether to use a certified component, or something that does the same job that is 'experimental'. In the long run, I think we can all agree that safety FIRST is the mission.
Tom