REFLECTOR: Fuel Line Routing (was Hub-bub)

Sat Jun 21 16:45:24 CDT 2014

That is one way to look at it.

It is quite by accident that I acquired this aircraft. I won’t go into that here.

I’ve had my Long-EZ plans since the early 80’s and started building my plane from the plans roughly 7 years ago and I’m just about done with the airframe. I state this as background material so you don’t think that this is my first rodeo. I know composites quite well and I know canards quite well.

>One of the most common cause of fatal accidents in experimental aircraft is mechanical 

>failure related to the fuel system.

When I got the Velocity the first thing I did was research on that aircraft using the NTSB database. Looking at the first accident that came up in the results the first link in the chain of events that followed was an empty (or near empty) tank due to uneven flow. This along with Burt Rutan & Mike Melvill’s write-up regarding the On-Off type fuel systems (i.e.feeding from both tanks at once) and why it is a bad Idea.

The system I currently fly is Left/Right/Off. The system I am installing adds “Both” to the option list. So you see if you were to compare my system to what you would propose I think that you would find that my system is a much closer portrayal of a certified aircraft design than a homebuilt/experimental design.

Now citing your argument below, would you suspect that you odds would be better if you were closer to what is typically a certified design approach?

>There have been multiple incidences of engine stoppage in experimental pusher aircraft 

>with the configuration you are describing (Scott B. described the mechanism in his earlier 

>e-mail). This would theoretically be less likely with a 200hp engine, but the inherent 

>risk/design limitation is there.

I would be interested in references that would support that statement. The point you make in your second bullet does not apply. That was related to long runs of 3/8” lines where I have a relatively short run of 1/2” lines with a minimal number of fittings. Fuel flow is retarded more by the number of fittings than the actual length of the tubing and I have seen demonstrations proving that point. 

>In the event of a "traumatic" arrival, with the valve up front, there is fuel essentially in your 

>lap

I find that unlikely but if the arrival is traumatic enough to cause such a failure …… well, no more worries. On the other hand, with a proper fuel system you may just make it to your destination. 

Burt and Mike were pretty factual in their argument and it did make sense to me. It just so happened that a Cozy flier trashed his plane about that time due to a combination of a missing gas cap and a single sump system.

I like what you have done Larry. I think you were very thorough in your approach. It’s just not what I’m looking for in my plane. I just would not feel comfortable going that route.

Tom Mann

N951TM

Sent from Windows Mail

From: reflector at tvbf.org
Sent: ‎Saturday‎, ‎June‎ ‎21‎, ‎2014 ‎3‎:‎13‎ ‎PM
To: reflector at tvbf.org

I know I'm not about to answer your question (Scott B. just did that beautifully on another post), but you may want to consider the following; 
One of the most common cause of fatal accidents in experimental aircraft is mechanical failure related to the fuel system.

There have been multiple incidences of engine stoppage in experimental pusher aircraft with the configuration you are describing (Scott B. described the mechanism in his earlier e-mail). This would theoretically be less likely with a 200hp engine, but the inherent risk/design limitation is there.

In the event of a "traumatic" arrival, with the valve up front, there is fuel essentially in your lap.

You could return the Andair valve and instead install a mechanical valve near the sump, which is actuated using pushrods in the front. There are multiple builders who have done this, who can add details (can also be found in the Reflector Archive).

Just a thought.

Larry

On Sat, Jun 21, 2014 at 11:59 AM, Velocity Aircraft Owners and Builders list <reflector at tvbf.org> wrote:

Okay, I’ll bite. 

Let’s try this.

The Background:

I have a Velocity STD/RG that I acquired. It has no fuel selector valve or shut off of any kind.

There  a known issue with the tanks draining unevenly to the sump.

I have rebuilt the sump as a split sump with two 3/8” lines on each tank leading to the sump.

There is a 3/8” vent line from each side of the sump and each wing tank to a central manifold and then to the exterior. There is also a alternate air vent to the manifold.

Lines from sump to the valve are 1/2” as is the line from the valve to the filter/pump/engine.

The Andair Fuel Selector valve that Velocity sells which has left/right/both/off options which is what I am installing. 

The Question:

I am looking for examples where builders have mounted the valve and how they ran the fuel lines. 

Has anyone used this valve in a Velocity RG with a center stick control system?

I have already received plenty of examples of various alternatives using cables, single point shutoffs, servo valves and the like so I won’t need any examples of those. Possible valve locations I have considered are the pilot’s side of the keel and top of the keel aft of the stick.

Or another location?

With the RG there will be the main hydraulic cylinder to contend with. That brings me to the fuel lines. I don’t know if I have enough room within the existing keel area or not. I may have to build a channel for the lines on top of the existing or down the side of the exiting channel.

For anyone using this valve in this configuration:

How did you address this issue of running fuel lines between the sump and the valve?

I have the rear bench seat but I would feel fine converting it back to bucket seats in the event that I need to raise the channel/keel to the back. 

Tom Mann

N951TM

Sent from Windows Mail

From: reflector at tvbf.org
Sent: ‎Saturday‎, ‎June‎ ‎21‎, ‎2014 ‎10‎:‎20‎ ‎AM
To: reflector at tvbf.org

On Jun 21, 2014, at 10:04 AM, Velocity Aircraft Owners and Builders list <reflector at tvbf.org> wrote:

So why is it that all these builders that did not use part “A” feel compelled to jump in and tell you about how they DIDN’T use part “A”?

Is this about disagreeing or perhaps something else?

I think its about knowledge, options and experimentation. I personally like hearing from those that installed part “A” and those that didn’t.  Many of us have not heard about the pros/cons of part “A”  and any options to do something different. Every post may not answer the question in the original post, but I, and I think others, benefit from hearing from those that have gone before us. If the original poster thinks the discussion is going too far off topic, then repost (nicely) and ask for a redirect to get back on track.

Tom

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