Fuel line penetration of the firewall

[macrafic]

It seems strange to me to use an aluminum fitting to go through the firewall with a fuel line. What is everybody doing? SS fittings? Gooping with fireproof sealant? Something else? Or, am I worried about nothing?

 

[MS19087]

I used a SS fitting . . .

just seemed better/stronger given it goes through the firewall.

 

[alpinelakespilot2000]

There's a doubler on the firewall here for stiffness and the gascolator is (probably) aluminum, so what purpose would the steel fitting serve that an aluminum would not? (Having said that, I agree that steel is better for fuel in general, and especially is more important on flex lines that fixed lines.)

 

[John Courte]

I'm trying to make everything that goes through the firewall or on the engine be steel if possible. For the firewall, I think the idea is to keep an avgas- and 200mph-fanned fire from melting your fittings and creating little blowtorches at your feet. Steel fittings might buy you enough time to cut off the fuel flow and get down before you can't fly the plane anymore, On the engine, they're less susceptible to fatigue induced by vibration and the stresses of connected hoses.

As far as I know.

 

[alpinelakespilot2000]

Good point. Not sure which is harder on fittings: airframe vibration on firewall or the movement of parts, even with flexible hoses, FWF.

As far as the fuel fitting on the firewall that's connected to the gascolator, if the fire makes it through the gascolator then it won't matter what whether the firewall fitting is steel or aluminum.

Again, though, I'm curious about whether the firewall fittings are prone to failure due to vibration issues. If so, I think that's the best argument for a steel fitting in this particular case. Just thinking aloud...

 

[jaradtke]

The aluminum fitting plumbs into the back of an aluminum gascolator, which is up against the fire wall. The gascolator is going to melt away before the fire gets to the aluminum fitting and fuel line.

 

[flyboy1963]

fuel, cabin air, brake, etc.

...in the long list of firewall penetrations, how 'bout them little aluminum brake reservoirs, and the PLASTIC fittings and lines.
Oh, and the fluid that flames at 200 F or so.

hmmmmmmm