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AeroCanard-FG Fuel Tanks

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I'm planning to purchase the FG plans but wanted to know more about the fuel tanks mods. The info kit says "No Switch/3.5 Gal Sump" for the FG. Does this mod truly get rid of the fuel selector valve? Could this mod be applied to a Cozy MKIV?

 

Thanks.

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The system is the left and right strake tanks connected directly to a sump tank either under the rear seat(s) or under the main spar. There is an on/off fuel selector between the sump and the electrical fuel pump to the engine.

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Yes, this mod could be (and has been) applied to the Cozy. Those that argue for a fuel system with no Left-Right fuel selector have some convincing arguments and statistics.

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Just a heads up... the AeroCanard FG plans do NOT specify the sump -- they're just like the Cozy Mark IV. The AeroCanard KIT is what has the sump.

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Both systems have their advantages and disadvantages. They are well documented elsewhere in this forum and in the Cozy email archives.

 

The proponents for "On-Off" see it as a fix-all to those pilots who make emergency landings due to fuel starvation in one tank only for the FAA to find the other tank full. The proponents for "L-R-Off" will cite forced landings due to entire fuel loads being sucked out of aircraft in flight. A good example being the recent Bill Oertel incident.

 

There's no perfect answer except know your own airplane, know your own fuel system, and don't get lazy.

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I still haven't made my mind up about this mod. It would introduce more fuel into the cabin, but cut down on the fuel tubing in the cabin.

 

I have had two aircraft in my control admit to venting most of their fuel out through an open filler by injudicious use of the the cross feed, and see this system as an automated version of that. If such things are available, I think a non-return valve in the line from each fuel tank to the sump tank would fix it.

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Thanks all for the responses. This mod is one of my top things to consider putting in since I've met people in my FBO that have forgotten to switch tanks and landed at the desert. I too have forgotten to switch tanks enroute because I've gotten busy with a controller and totally forgot about it.

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Spod- Thats a great idea I think- about the non-return valve in each L and R strake tank. Give me a McMaster Carr part number!!! The fuel venting during flight due to a lost fuel cap is the only real concern, I have heard, other than fuel contamination[reason for two separate tanks].

I would like to consider getting another 3.5 gallons of fuel available if the under spar sump is a good move.

More thoughts?

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I'm planning for left, right, and a 3-4 gallon sump tank under the main spar; behind the rear seat back. I've eliminated the switch valve and associated tubing.The only "switch" will be between the sump tank and fuel pump, ON or OFF .

 

The system has vent lines from each tank, left, right and sump, joining together high on the firewall. From there a single line continues to the highest possible point on the firewall before coming back down.

 

The system will also have a check valve with a "P" trap loop in it as a second vent in the cabin should the primary vent line become plugged from ice or other material. This is an idea from my friend Andy, he's building a Velocity.

 

 

FWIW...

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My flame suit is on..

What would be the drawback to my thinking here?

What my inclination to do upon hearing of the sump location under the spar..was to keep the plans valve and location, but connect that to that sump and then take the feeder line through the FW to the fuel pump from there.

I didn't want to throw away the plans valving, I just wanted to add the 3+gal of extra fuel said to be in the under-spar location..

This seems so reasonable to me that there must be some obvious catastrophic reason it won't work or is not a good idea.

??????????????????????

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I'm planning for left, right, and a 3-4 gallon sump tank under the main spar; behind the rear seat back. I've eliminated the switch valve and associated tubing.The only "switch" will be between the sump tank and fuel pump, ON or OFF .

 

The system has vent lines from each tank, left, right and sump, joining together high on the firewall. From there a single line continues to the highest possible point on the firewall before coming back down.

 

The system will also have a check valve with a "P" trap loop in it as a second vent in the cabin should the primary vent line become plugged from ice or other material. This is an idea from my friend Andy, he's building a Velocity.

 

 

FWIW...

 

Sounds good Carlos,

 

The only correction that I would suggest is to have more than one line to the highest point and then return down. The single tube gives a single point of failure at which time your entire fuel system is shut down. why bring a second line with a check valve into the picture, especially into the cockpit. Check valves don't always work as planned. KIS

 

What I have planned is 3/8" vents (2 in each tank-- rear and mid-- see previous posts on this subject) and one 3/8" from the sump going to a header high on the firewall. From there two vent lines 3/8" descend and point into the slip stream at the bottom of the firewall.

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I currently fly with a L-Both-R (pretty sure there is an "off" in there too) in my Cozy. I fly with it in both all of the time. If I am venting, I can switch to the side that is not venting to isolate the system. And yes, if you don't know it is venting, you could be screwed. But I do have the option to go left and right.

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I currently fly with a L-Both-R (pretty sure there is an "off" in there too) in my Cozy. I fly with it in both all of the time. If I am venting, I can switch to the side that is not venting to isolate the system. And yes, if you don't know it is venting, you could be screwed. But I do have the option to go left and right.

Drew,

 

are you seriously saying that you have an option to select a position which could be detrimental to your safety, security, or life, and you are satisfied with that?

 

Murphy and his law would be aghast.

 

"Well," said he to the FAA inspector from his hospital bed, " I selected a usable fuel tank but I didn't know that was not venting, but I knew that it had the possibility of not venting without letting me know. It had to be okay, however, because it worked all the time in the past.":irked:

 

A simple solution would be to have a vacuum sensitive switch in each tank or somewhere the fuel line which would give you an indication of negative pressure in that part of fuel system. Alternatively get rid of or defeat the ability of the fuel selector to select individual tanks so that the system will then vent through the operative side.

 

Just looking out for your assets.

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Sounds good Carlos,

 

The only correction that I would suggest is to have more than one line to the highest point and then return down. The single tube gives a single point of failure at which time your entire fuel system is shut down. why bring a second line with a check valve into the picture, especially into the cockpit. Check valves don't always work as planned. KIS

 

 

The thought behind the check valve is the valve is in the cabin where it wouldn't be affected by external foreign matter like ice. Two vent lines will ice up as good as one.

 

Should the main vent tube be clogged the check valve will open and allow the tanks to vent properly. If the vent line is clear the check valve will remain closed.

 

That's what I'm thinking to do... That and 1/2" fuel and 3/8" vent lines.

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The thought behind the check valve is the valve is in the cabin where it wouldn't be affected by external foreign matter like ice. Two vent lines will ice up as good as one.

 

Should the main vent tube be clogged the check valve will open and allow the tanks to vent properly. If the vent line is clear the check valve will remain closed.

 

That's what I'm thinking to do... That and 1/2" fuel and 3/8" vent lines.

Carlos, Me Bud,

 

That all makes academic sense. However occasionally one way valves malfunction and become 2 way valves, be it by a bit of contamination on the seat, bad manufacturing or just bad design. (ever had a tank drain valve not stop draining-- yes I know they are o ring operated-- but all mechanical things are subject to malfunction)

 

If this happens, then you have a nice soda straw from the fuel system into the cockpit. Choose your drink.

 

If you are concerned about a similar set of circumstances affecting all of your vents, locate them in different positions. You need some way of equalizing the pressure ie. a manifold. You could copy Cessna for one, (and additionally put a one-way valve in it, if you wish) and locate it in back of the gear leg. (Cessna locates their vents behind the wing struts be aware that this location may, in fact induce a negative pressure).

 

I have no problems with the larger fuel lines, although to get same into pumps and/ or valves you will probably have to use fittings that will cut them down to 3/8 or smaller equivalents.

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