Carb Fuel Line Question

[nippaero]

I finally got a change to pull the cowl off the 170. Should the fuel line to the carb have a fire sleeve on it? I am used to having fire sleeves or Aeroquip 466 on my O320 in my RV.

[bagarre]

it's not a pressurized line. A fire sleeve is not required.

[nippaero]

Ok thanks. Sorry for the questions but I am having to re-think things after spending so much time in the Experimental world. Can a hose like this be replaced with say Aeroquip 303 or does one have to use a certified part from Cessna or something like that?

[flyboy122]

Just because it isn't required doesn't mean it's not a good idea. Mine are all firesleeved.

Aeroquip 303 would be fine as long as you use correct fittings and assembly procedure. No need to buy the official Cessna part.

DEM

[DaveF]

In my opinion, all fuel hoses forward of the firewall should be firesleeved and all fittings should be steel. Go with the Teflon AE466 integral firesleeve. Not only is it nice and neat, but it has no calendar lifetime, unlike the rubber hoses.

The hose is considered a generic part so you can use any hose that meets requirements for material and pressure. There are very few hoses that must be replaced with Cessna parts. A few of the Cessna 210 gear hoses fit that description.

[canav8]

Nippaero, On old fuel line, no fire sleeve was required. There are a few requirements that affect the way aircraft fuel and oil systems are constructed for Type Certificated Aircraft. FAR § 23.99: Fuel system lines and fittings. (e) No flexible hose that might be adversely affected by exposure to high temperatures may be used where excessive temperatures will exist during operation or after engine shutdown. And §23.1183 Lines, fittings, and components. (a..., each component, line, and fitting carrying flammable fluids, gas, or air in any area subject to engine fire conditions must be at least fire resistant, ... Flexible hose assemblies (hose and end fittings) must be shown to be suitable for the particular application...
You must use external fire sleeve if you are not using Aeroquip or Stroflex hoses when you replace the old lines. Doug

[nippaero]

Thanks for the info guys.

[n2582d]

Nippaero, On old fuel line, no fire sleeve was required. There are a few requirements that affect the way aircraft fuel and oil systems are constructed for Type Certificated Aircraft. FAR § 23.99: Fuel system lines and fittings. (e) No flexible hose that might be adversely affected by exposure to high temperatures may be used where excessive temperatures will exist during operation or after engine shutdown. And §23.1183 Lines, fittings, and components. (a..., each component, line, and fitting carrying flammable fluids, gas, or air in any area subject to engine fire conditions must be at least fire resistant, ... Flexible hose assemblies (hose and end fittings) must be shown to be suitable for the particular application...
You must use external fire sleeve if you are not using Aeroquip or Stroflex hoses when you replace the old lines. Doug

While it is a good idea to conform to part 23 requirements, our aircraft were certified in accordance with CAR 3. The applicable regulation for fuel lines is this:

LINES, FITTINGS, AND ACCESSORIES
§ 3.550 Fuel system lines, fittings, and accessories. Fuel lines shall be installed and supported in a manner which will prevent excessive vibration and will be adequate to withstand loads due to fuel pressure and accelerated flight conditions. Lines which are
connected to components of the airplane between which relative motion might exist shall incorporate provisions for flexibility. Flexible hose shall be of an acceptable type.

I've added this article on maintaining flexible fuel hoses to the Maintenance Library. Page 6 shows some things to watch out for regarding hoses with firesleeving.

[ghostflyer]

Having the Teflon AE446 hose is the best , it's not a life item but goes on condition , BUT looking at the photo of your fire wall there is a lot of GREEN stains indicating a fuel leak .

[nippaero]

There were no leakes that I could detect. I was using a rag soaked in old gas to wipe down everything. The gas really cuts through all the oil and grime.

[nippaero]

I just got to thinking today while working on my O-320 in my RV6 that I never saw a fuel pump on my new C170. The fuel line goes straight from the gascolator to he carb. Is that normal? Was it an option from the factory? I am guessing it just relies on pressure form gravity

[gfeher]

Yes, the fuel line goes straight to the carb from the gascolator. It's a gravity-fed fuel system from the tanks to the carb. No fuel pump is needed or approved for the stock C145/O-300 on the C-170s. Simplicity at its best.

[cessna170bdriver]

...No fuel pump is needed or approved for the stock C145/O-300 on the C-170s. Simplicity at its best.

Unless it's a ragwing.

[blueldr]

I have found that quite a few straight C-170 airplanes (Ragwings) are operating successfully without a fuel pump although a fuel pump is actually required to be completely legal. The fact that the required fuel pump is an automotive type operating off of a lobe on the camshaft, it is a damn site more expensive than a very similar one used on your old '38 Chevy. After all, it's going to be installed on some rich guy's airplane. I strongly believe that's why a good many of them have been left off of the engine.
I've never heard of a case of fuel starvation on a C-170 that is operating without a fuel pump.

[edbooth]

I believe Duane Shockey (CA) replaced his engine mounted pump with an electric fuel pump. Did this several years ago.