Fuel Question

Aaron wrote:

Don't you think the fuel injection hose is much better at handling the ethinal than barricade carb hose?

I'm assuming that is one of the reason I have to change hoses on the plane every 5 years and my 20 year old vehicle still has same fuel hose

When E10 became available in the Australian market it wasn't long before problems with "rubber" (generic term covering most flexible components) started to occur.

Manufacturers were quick to adjust and now most if not all rubber components are Ethanol compatible (reputable manufacturers will have detailed performance data that you can access - I use Gates).

In the 12 or so years I have been involved with Rotax they have always advised 5 year rubber replacement (I think this predates the advent of Ethanol blended fuel)- this is not about Ethanol as such - it is a recognition that most rubber components change over time (even when stored on the shelf). This changed is accelerated by exposure to chemicals (fuel, oil, coolant, etc) temperature (engine compartment), repeated movement (fatigue) and even UV (sunlight). A hose failure in a car, may result in pulling over to the side of the road & the driver seeking assistance. An aircraft with a leaking hose may catch fire/engine failure, with catastrophic results.

Ground based systems (your car) are not usually subject to the same level of failure/safety concern, compared with an aircraft. The fact that some of your hoses, seals, etc might be showing signs of "perishing (stiffer, cracking, etc) than they were 5 or more years ago is not often checked/of concern. (My 29 year old 4x4 had still has the OM radiator/coolant hoses - I accept a small oil leak around the crankshaft seal).

I recycle my old Rotax hoses onto my lawn mowers, as spacers and wear prevention sleeves.

vapor recovery or Carb hose has the same resistant to ethanol as fuel injection hose. The only real difference is the amount pf pressure they were each set up to handle. The 30R9 interior material is the key.

Both types of hoses have this.

Polytetrafluoroethylene hoses or PTFE have solved the shortcomings of dissolving neoprene rubber hoses transporting fuels with Ethanol.

In a research project I did a while back I found most hose deterioration and damage under the clamp and not in the middle of the hose. Squeezing the hose especially on top of barbed fittings causes issues. The big issue is people almost always over clamp the hose which causes that damage. I have numerous pictures that showed these damaged areas. 

Roger L

"The only real difference is the amount pf pressure they were each set up to handle." 

Possibly I am being pedantic -

In the Gates range of fuel hose (the ones I use) Fuel Injection(FI) hose has, in addition to a higher burst pressure than Carburettor hose, lower vapor/gas permeability and higher temperature resistance/tolerance.

The FI high hose busts pressure has no benefit in my low pressure fuel system.

However the lower permeability may assist in reducing fuel smell in the cockpit and the higher temperature tolerance may just give a few more seconds before my aircraft is consumed by fire.

I purchase my Gates hose through the Australian dealership - they are able to give me an FI hose price /meter only a little more than the carburettor hose. The difference in price, over the quantity I am purchasing, is only a few dollar.

I perceive the cost benefit to be in favour of the FI hose.

I've been using the Gates barricade vapor recovery hose for 20 years and all most all use 91 oct. with ethanol. Never a single issue. I still use it today. Even Rotax has used gates hose. It was in an SB. Many other owners and mechanics have been using it for years and no issues. Actually the fuel injection hose has caused some issues. i.e. carb debris. because the FI hose and less give you many times have to force it over barbed fittings that many use and this scrapes off the inner liner and causes small debris to float to the carbs and since the inner liner gets scraped at the fitting it's more susceptible to increased damage there. The old standard rubber hoses of yester-year did have more permeability, but today's hoses are far better and that isn't an issue if they have the proper inner liner. Hoses have evolved because of fuel changes. When I did my research project many years ago I talked directly to Gates hose engineers.