[Harold Lanfear]

Vans uses an aluminum bulkhead fitting where the fuel line passes through the firewall. After changing over my heater fitting from aluminum to stainless steel, it occurred to me that another potential problem could be the aluminum fuel line bulkhead fitting. Anybody out there with knowledge regarding this or is this overkill? AC 43.13 doesn't address it that I could find.

Thanks, H

 

[G-force]

Not much of an answer, but my plan is to have nothing but steel, stainless steel, or fire sleeved looms penetrating my fire wall.

 

[DanH]

<<I am working on my firewall right now and I see all these stainless steel parts for sale but aren't they all still attached to an aluminum firewall?>>

Ahhhh, let's hope that firewall you're working on isn't aluminum.

Firewall choices are plain common sense. The basic rule is that if it won't survive 2000F, it doesn't belong in a firewall penetration. Work as close to that standard as you can.

 

[Low Pass]

Vans uses an aluminum bulkhead fitting where the fuel line passes through the firewall. After changing over my heater fitting from aluminum to stainless steel, it occurred to me that another potential problem could be the aluminum fuel line bulkhead fitting. Anybody out there with knowledge regarding this or is this overkill? AC 43.13 doesn't address it that I could find.

Thanks, H

If it makes you feel better, then do it. But if you're going to go with steel bulkhead fittings, you should follow with steel all the way to the carb. I prefer steel (oil and fuel fittings) in the engine compartment for strength, personally - to hopefully prevent a failed fitting in the first place. If there's a blazing fire inside my cowling for more than just a few seconds, I'm shutting all fuel off and heading for the deck.

 

[f1rocket]

I don't think this has been mentioned yet, but I think an important reason for using steel is the added strength. When you attach a floppy hose to an aluminum fitting, you can stress the fitting to the point it might eventually break off. This is expecially true if you use production hose assemblies that are constructed with stainless fittings.

FWIW, everything firewall forward on my ship is steel that pushes oil or fuel, and every penetration in my firewall is steel as well. Even if it saves me 15 seconds in a fire, that might be all the extra margin of safety I need to get down.

 

[alpinelakespilot2000]

Vans uses an aluminum bulkhead fitting where the fuel line passes through the firewall. After changing over my heater fitting from aluminum to stainless steel, it occurred to me that another potential problem could be the aluminum fuel line bulkhead fitting. Anybody out there with knowledge regarding this or is this overkill? AC 43.13 doesn't address it that I could find.

Thanks, H

I'm just working on my 9 now and my aluminum fitting goes straight through the firewall into the back side of the gascolator. Van's instructions say to use a bead of RTV around the back of the gascolator where the firewall penetration is. Wouldn't a fire have to burn all the way through the gascolator before it could get at that alum fitting?

 

[Low Pass]

...Wouldn't a fire have to burn all the way through the gascolator before it could get at that alum fitting?

The RTV is a fire resistant seal used to prevent hot gasses/flames from flowing though the void between the fittings/gascolator and firewall. With this hot gas flowing through even a small void, it could cause more damage than flame impingement alone. Much like firestop (RTV) penetration sealants used in commercial buildings between fire & smoke walls.

 

[mburch]

FWIW, everything firewall forward on my ship is steel that pushes oil or fuel, and every penetration in my firewall is steel as well.

Hey Randy,

Just curious, how did you bring the engine control cables through the firewall without using aluminum fittings? I just went through the process of selecting and installing eyeball fittings and I was disappointed to learn that the steel eyeballs that are commonly available can only handle cables up to 0.26" diameter. I had to go with the aluminum eyeballs instead since the diameter of Van's cables is more like 3/8".

mcb

 

[Steve Sampson]

Steel rivets?

I have puzzled about this issue of steel .v. ally. Are we not being a little overly concerned since the rivets are all made of aluminum?

I am seriously questioning where the boundary on this issue is?

 

[GAHco]

Rivets on firewalls

Certified Airplanes use Steel, Monel, and Stainless Steel Rivets for the firewall.
Its been that way for at least 25 years.

I sell a lot of them.