Cy Galley wrote:
The 37° is the angle of the taper seal in aircraft fittings. Automotive uses
45°. So when you work on an aircraft, that is what you expect. Mixing the
two could be a big problem. With that said, My Factory built Bellanca has
two different style fittings as it was built with war surplus Air Corp
fittings. Since they are no longer available, some of the later repairs and
alterations use the current style fittings. They are both 37° but the nut
threads are different. AC fittings were gray, Current are blue.



So when you put automotive parts in an aircraft...

That is not a joke, BTW.

Very good answers from several people. Thank you Cy, Jerry and Kevin.
But your answers all beg the question, "If the 37 flare holds better and
is less likely to damage the hose...why would anyone standardize on 45?"

Is the 45 easier/cheaper to make?

--
http://www.ernest.isa-geek.org/
"Ignorance is mankinds normal state,
alleviated by information and experience."
Veeduber