I=99m reminded of the value of this list after contacting Ron
Pagoris who had not posted for a long timeand I want to thank
him for bringing to my attention the subject of the use of aluminum fuel
line fittings in the engine compartment.
Further research on the subject generated this response from Bud which
he willingly shares with our list:
> Fred,
> I do not have problems with aluminum AN fittings. I do have problems
with FWF techniques:
>
> AN fittings or even steel flare fittings need some sort of fastening
to prevent loosening, which is common. I see some of the fittings you
use have a safety wire hole. Use it. They do loosen, especially on
fuel injection lines. Hence the automotive and marine industry is going
to special fittings. Oil fittings get safety wiring also.
>
> I also have problems with any hard line going to an engine, from a
firewall. That is a broken fitting waiting to happen. The engine to
fuselage fitting should always be a flexible line of course. If the
line is steel braded or firm rubber, its flare fitting will tend to
loosen with age without some sort of fastener fixing them such as safety
wire or crimp anti spin connector. Reason, over time the shake of the
engine and the firm rubber or braded line will shake until the flare
fitting begins to loosen. We had this problem on jet engines. Safety
wire flare fittings in some way. If the flare fitting has no safety
wire hole, I use a Breeze clamp bent to fit on a fitting (like on the
oil tank fittings on the Rotax) rather than drilling the nut edge. Once
I have the Breeze clamp fitted, I safety wire the Breeze clamp screw so
it won=99t loosen, then safety wire the clamp to a fixed point to
assure the fitting stays tight.
>
> That said, I tend to use push on or barb fittings screwed into an NPT
fitting for oil and fuel with specified clamps so the fitting won=99
t loosen. However, Aluminum NPT fittings can crack if not supported
properly, maybe that is why your inspector prefers brass, which bends,
or steel which is much stronger. He may have been concerned about the
90 degree fitting coming off the fuel line manifold for bending. I
can=99t say. What I can see in the photo looks like a safe
fitting if it is suitable for the fuel or oil temp and pressure
requirements of the engine manufactuer.
>
> Best Regards,
> Bud Yerly
While I will continue with my aluminum fittings, I will most certainly
ensure that they are properly safety-wired! Thanks Ron & Bud!
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