Savannah fuel setup

[Marty_d]

Hi all,

 

Given that I've got Sav wing tanks installed, I'll probably get a header tank as well.

 

At the stage now where I need to drill holes through the seat front, which are for rudder cables, elevator trim cable, fuel and brake lines (left and right). There's another hole too but I can't remember what that's for.

 

I've got some questions about the Sav fuel setup if that's ok...

 

1) Does the header tank remove the need for a gascolater?

 

2) Anyone done rigid (aluminium) fuel lines?

 

3) Assuming I end up with a Rotax, does the return line go to the header or one of the tanks?

 

4) Anyone got some pictures of fuel lines within the fuselage?

 

5) If I want a selector (Left/Right/Both) where does that go?

 

6) Is there a line between the two tanks to balance them, or is that a bad idea because of unexpected fuel movement?

 

Thanks in advance,

 

Marty

 

 

[Kyle Communications]

Marty Its a controversial subject :) My system has 4 tanks all individual coming to a 4 way manifold with separate switches for each tank. The output for that goes into the top of the collector tank. The other inlet into that collector tank I use as a breather that goes all the way to the top of the pax side inner tank . My overflow from the rotax fuel system goes back to the manifold and enters there but I do have a tap on it so I can tuen it on or off as I want or need to. This way I do not get vapour locks in the collector and I have full control of all fuel in the aircraft at a individual tank level. I have some pics I will find and post them here. I am dying from the man flu at the monent so will get out to the shed soon and get some pics for you. The fuel pipe system in a Sav uses a lot of alu tube connected with lengths of hose..it stops a lot of vibration issues

 

Mark

 

 

[Marty_d]

Thanks Mark, you've already answered something I was wondering about - didn't know whether the return line went to the tank or the collector. Makes sense that it goes to the collector then a separate breather line from collector to tank.

 

Glad it uses aluminium - I've read in other places that it's better to have a rigid fuel system and I've been wanting to go that way. Any idea of the pipe size?

 

Hope you kick the flu soon, I'm also suffering from a cold but over the worst of it.

 

 

[Kyle Communications]

The return line from the motor is supposed to go direct to the right inner tank but I changed mine when I made the manifold so that the return goes direct into the side port of the manifold...it will become clearer when I post some pics. The fuel lines from the collector to the engine are made up from alu tube mostly but do have rubber hose in parts so it sort of breaks it up. It comes from under the front floor from the main fuel switch then around the corner at the firewall then in mine it goes to a gasculator/filter then up to the fuel splitter

 

 

[IBob]

Mark, I am pretty much following your scheme, which makes every sense to me.

 

1. This will include the Rotax overflow going back to the manifold. You say you have a valve on that. What is your thinking there, please?

 

2. I was having a conversation as per Marty's question 1 above: Does the header tank remove the need for a gascolator. Any thought on that one?

 

Get well soon...some nasty late winter stuff going round here too.

 

 

[Kyle Communications]

I didnt have a gascolator originally I had that stupid motor mower filter they supply so I wanted something better so looked at a few and the one I have I got locally it has a filter inside it but its not too fine. What I did though is I shifted my fuel pump to under the seat to get it away from the firewall and that stupid cover it had and was also a nightmare to get to. Its now easier to get to through the access hole also I have a sealed proper fuel filter at the bottom of the collector now and I change it every 12 months or so. I have a new one here I am about to replace now. The pic showing the girlfriend you can see the system on the pax side of the wall behind the seat so it is easily got to while flying. The one showing the manifold and hoses you can see the right hand end where the fuel return from the engine comes to into the end of the manifold and I have a tap there in that line so I can turn it off. I turn it off to see the actual fuel flow to the engine as my fuel flow sender is on top of the engine at the new fuel spitter I made as the kit one I repaired 3 times from leaking it was crap. I have attached some pics of the one I made. Its a little heavy as its all brass but works a treat and of course gives me the fuel flow sender point. Also I modified my oil pressure sender position. When its mounted on the block they fail due to vibration especially the older type with the resistor. I had the honeywell one electronic type but it failed at 150 hours and they want another 400 bucks for another so I used the older VDO type as they are cheap and just as good but fail because they are attached to the block so I made a flylead up and you can see it now on the top of the motor near my fuel splitter and it works fine. My MGL Xtreme Rdac can take in either type of sender unit

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[Kyle Communications]

The gascolator also traps any water that may get through the system and of course has a filter and it was what help me diagnose the issue when Mike was flying and the engine went stupid..coming across Moreton Bay..when he landed to get back on the ground in a hurry is when the noseleg got snapped off and I had to fix her up. I thought it was throttle cables but after I replaced them all and checked everything I could when I started the engine I was doing full power runs when the engine wanted to tear itself out of the mount...this is what he experienced coming across the bay...it ended up being a blockage in the fuel line. A piece of thin plastic from inside the fuel tank..had come off and gone all the way down the system and got trapped at the bend of the alu pipe where it comes under the firewall. This was before I had the sealed filter between the gascolator and the collector. This was causeing the bowls in the engine to empty at full power so the engine was starving as this plastic had turned sideways in the alu pipe. I found it when I turned on the drain tap on the gascolator..fuel was not gushing out it was trickling out so I chased why and that is what caused the whole issue. So having one I think is a good thing for the filtering it does and allows other diagnosing of any issue

 

 

[Kyle Communications]

I hope I have answered your questions Marty...I think the way I have done the fuel system is the easiest and most logical way of keeping full control yet simple to operate and also takes away the problems with fuel locks that many savannahs seems to get

 

The only issue I ever had was when a insect blocked a tank breather in the cap when I was using the std breather system in the kit. I got rid of that and now have the pipes in the caps and now its perfect. I found that early as well because I could see that tank was not emptying. This is why I like full control of the whole fuel system. I was able to redo my fuel tank scenario and get to a airfield where I solved the issue. I had plenty of time to make the decisions

 

 

[Marty_d]

The one showing the manifold and hoses you can see the right hand end where the fuel return from the engine comes to into the end of the manifold and I have a tap there in that line so I can turn it off.

Yep that's pretty clear Mark, very nice setup.

 

Just a question about the return from the engine though - so I get that it goes back in to the end of the manifold. Have you got a one-way valve or something? Just wondering why the fuel pressure from the tanks wouldn't force fuel backwards through the return line, or is the pressure from the return line more than the gravity flow from tanks?

 

 

[Marty_d]

Also - do I have this right - looks like you're not using the 7L header tank that the Savannahs usually have, you're going straight from the manifold down to the bottom filter then along to the pump?

 

 

[Kyle Communications]

The second input to the top of the collector is my breather. You cant see it in the pics but it comes from the collector then goes all the way up the side of the aircraft and connects at the top of the inner right side tank at the pipe I have coming out of the tank for my fuel sight gauge. The total fuel weight overcomes any pressure from the engine return which is about 3 litres per hour which is quite low anyway. We are working on a system to see how much fuel you have left at the moment and it works on that pressure idea. The other end of my manifold has a plug in it. We think a pressure gauge will show how much "weight" you have in fuel. If you only have 1 tap open you will see how much fuel will be in that tank and you could do that with all tanks or one at a time. The pressure required will be small but a gauge that goes from 0 to 2 PSI we think will do the trick and it can be callobrated easily with volume etc and all the fuel being about 500mm head from the gauge it should work so thats another project we are working on

 

 

[Kyle Communications]

That single pipe from the bottom middle of my manifold goes into 1 of the 2 inputs at the top of the sump/collector and the other opening in the top I use for the breather as explained above

 

 

[Kyle Communications]

sump/collector = 7 litre header tank

 

 

[Kyle Communications]

The hole in the original savannah splitter Tee for the fuel bleed back to the tank is 0.3mm this gives about 3 litre per hr...mine is about 0.4mm that I made and I can see this when I turn that tap on and off on the fuel return line. As the system is essentially a closed system that fuel return pressure doesnt really make any difference I think as it all just levels itself out in the long run

 

 

[IBob]

Mark, I am pretty much following your scheme, which makes every sense to me.1. This will include the Rotax overflow going back to the manifold. You say you have a valve on that. What is your thinking there, please?

2. I was having a conversation as per Marty's question 1 above: Does the header tank remove the need for a gascolator. Any thought on that one?

 

Get well soon...some nasty late winter stuff going round here too.

Hi Nobags.

 

The Savannah has a vertical collector tank which sits on the floor behind the pilot's seat. This is the low point in the fuel system.

 

The base of the tank is recessed downward at one point, below the fuselage skin, with a bleed valve fitted. Fuel is taken from a point 30mm up from the base of the tank.

 

Forward of the firewall, it is then usual to have a fuel filter.

 

(Apologies here if I am pointing out what you already know!)

 

That being the case, I am not sure what extra protection a gascolator offers. Hence my question.

 

 

[Kyle Communications]

Nobags? hahahhaha is that me?

 

There is no real need for a gasculator Bob. It just so happened that I replaced the filter with the gasculator. You have to remember these mods are done over a 6 year period. The plane has had 2 different dashes and instruments also mods to fuel tanks and pipes and fittings , dual sticks , flap brackets etc.....I have always maintained that its a work in progress..maybe its because I like to "fiddle" with things on her

 

 

[IBob]

Nobags? hahahhaha is that me?There is no real need for a gasculator Bob. It just so happened that I replaced the filter with the gasculator. You have to remember these mods are done over a 6 year period. The plane has had 2 different dashes and instruments also mods to fuel tanks and pipes and fittings , dual sticks , flap brackets etc.....I have always maintained that its a work in progress..maybe its because I like to "fiddle" with things on her

No, not you: a member called Nobags put a Caution on my earlier question here.

 

But thanks for your thoughts. And yes, even by build seems to be some sort of evolution.........)