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Tip: AN fittings
- Thread starter N395V
- Start date
az_gila
Well Known Member
Well, yes and no....
...the steel ones from the hydraulic shoppe might be stronger than the AN aluminum ones, but they are equally deficient in strength over a genuine steel AN fitting (the ones without a "D" on the end of the part number).
From the article...
The most notable difference between these standards are in the threads. AN fittings use a reduced root radius thread ("J" thread) and a tighter tolerance (Class 3) to achieve a 40% increase in fatigue strength and 10% increase in shear strength (thread tensile stress area of 110.76 compared to 103.20 mm2)
This drop in strength is due to less metal, so a steel hydraulic shoppe one, with Class 2 threads, is still 40% weaker than an AN steel one - and that assumes an equal grade of steel...
You are not comparing apples to apples....
...the steel ones from the hydraulic shoppe might be stronger than the AN aluminum ones, but they are equally deficient in strength over a genuine steel AN fitting (the ones without a "D" on the end of the part number).
From the article...
The most notable difference between these standards are in the threads. AN fittings use a reduced root radius thread ("J" thread) and a tighter tolerance (Class 3) to achieve a 40% increase in fatigue strength and 10% increase in shear strength (thread tensile stress area of 110.76 compared to 103.20 mm2)
This drop in strength is due to less metal, so a steel hydraulic shoppe one, with Class 2 threads, is still 40% weaker than an AN steel one - and that assumes an equal grade of steel...
You are not comparing apples to apples....
Last edited:
frankh
Well Known Member
Well yes and no
I wouldn't use steel fittings all through the airplane but for the odd fitting they are great. They are available locally and significantly cheaper.
For me though the fact they are steel means you can weld fitting together to make custom jobs like I did for the fuel pump installation in the wing roots..I needed something like a T with a #4 O ring boss on one leg and an AN6 on the other....Welding is the easiest way and I don't have a Tig welder.
If I were doing it again I would probably use oil cooler hoses from the hydraulic shoppe though.
Frank
I wouldn't use steel fittings all through the airplane but for the odd fitting they are great. They are available locally and significantly cheaper.
For me though the fact they are steel means you can weld fitting together to make custom jobs like I did for the fuel pump installation in the wing roots..I needed something like a T with a #4 O ring boss on one leg and an AN6 on the other....Welding is the easiest way and I don't have a Tig welder.
If I were doing it again I would probably use oil cooler hoses from the hydraulic shoppe though.
Frank
