Help Wanted (with metal fuel line plumbing)

[skippydiesel]

My new aircraft's fuel reticulation system, is very much as per a certified aircraft, in that its all metal (except for small sections in engine compartment) - I need to make modification  to the system.

 

A further complication, is my dislike of the imperil systems (I think the tube in OD 3/8") which makes ordering parts a very onerous (& error prone) task.

 

I lack, both the experience (past aircraft was almost all "rubber" fuel hose & all metric) and the necessary equipment (I do have a small tube cutter & a primitive small tube bender that may suffice but no aviation flaring equipment).

 

I am hoping some kind Forum member(s) will make good my lack, by supplying advice, particularly in the ordering of parts and may also assist with tools (borrow/hire/purchase).

[old man emu]

Skippy,

Are the dimensions used in your plans metric or imperial. If they are imperial, then you will be using MS parts.

  

 

Why not go down to GB Aviation at Camden ( used to be Dent Aviation) and ask Rodney to flare your tubing for you. Or got to Delta and ask Derek to do it. 

[skippydiesel]

Thanks for suggestion OME - I have a passing acquaintance with, what is now GB Aviation (& Rodney) - they are very helpful but I am reluctant to impose/interrupt their commercial activity.

 

The flaring is the least of my concerns - purchasing the correct parts looms much larger in my mind. 

 

I think the fittings are AN style eg

A quick check through the EEA catalogue, has pages & pages of offerings.

 

I think what I am after may be AN-6 (for the most part) but then if I order say an AN827-6-D (3/8 aluminium Cross) does it come with Nuts, or do I have to order AN818-6-D  (Flared tube nut, aluminium, .375) & is this compatible with the Cross & tube system??????

[old man emu]

Skippy,

AN is the old designation for what is now MS in the above material. Same dog, different collar. If you don't want Rodney to do it immediately, I'm sure he would get a  round tuit for you.

[skippydiesel]

 

Still listed as AN in the AAE Catalogue, Pages 153-171 https://www.aaestore.com.au/ and in Aircraft Spruce (limited listing) - AAE also do a limited amount of MS (green) but no where near the vast offering of AN (blue)

 

Rodney is very obliging but I cant see taking up his time to organise an order for multiple fuel plumbing parts - he doesn't live far from me - if all else fails he may take pity on this poor (metric only) klutz.

 

Aircraft still flying , when weather & other consideration's align, however will be relocating from The Oaks to home workshop, in the ,yet to be decided, near future ,to make a host of changes (including fuel reticulation).

 

Seeing as you have been reckless enough to answer my call - perhaps you would like to see the Sonex at The Oaks with a view to helping with parts order???? Unfortunately cant offer you a flight ,as still under Flight test regime.

Edited May 2, 2023 by skippydiesel

[Marty_d]

I put metal fuel line in mine, bought a little beading tool from Aeroflow - AF98-2020 - PIPE BEADING TOOL SUIT 3/8" 

That allows you to make your own barbs at the end of the line,  then hose clamp regular fuel line to it. 

[rgmwa]

Make sure you get a 37 deg flaring tool with AN fittings, not the standard automotive one.

[Thruster88]

If you have a rough diagram of what are need i am sure Rodney or any other LAME would help you. They may even have all the fittings in their store.

 

I am curious why you need to modify the fuel system, is it in accordance with the sonex build manual? Have you obtained advice on any modification 

 

None of the fittings (nipples, elbows or crosses)  come with nuts because they are usually part of hose assembly.  

Edited May 2, 2023 by Thruster88

[skippydiesel]

27 minutes ago, Thruster88 said:

If you have a rough diagram of what are need i am sure Rodney or any other LAME would help you. They may even have all the fittings in their store.

 

I am curious why you need to modify the fuel system, is it in accordance with the sonex build manual? Have you obtained advice on any modification 

 

None of the fittings (nipples, elbows or crosses)  come with nuts because they are usually part of hose assembly.  

I never considered Rodney might have the fittings I need - will contact him in the next day or two.

 

Very much a non standard, plans built, Sonex/Rotax 912 ULS - has 30 L x2 wing tanks and a 40 L header (where the standard 60 L fuel tank sits) being a header it can only be filled by transferring fuel from the wing tanks.

 

Take it from me, the fuel management system needs several changes,  including a non return valve supply around the Boost pump.

 

Being a 19 (homebuilt) I do not need to obtain advice from Sonex (who have already disowned her, due to the wing tanks & other personalisation's) but am always open to constructive advice from any knowledgeable person.

[IBob]

Does the booster pump not have an internal (non return) bypass, or some arrangement that provides that function, Skippy?

Edited May 2, 2023 by IBob

[Blueadventures]

What's the Lame hourly rate there.  Up here $190/hr.

[old man emu]

3 hours ago, skippydiesel said:

never considered Rodney might have the fittings I need

I used to run the aircraft hardware sales business associated with Dent Aviation, now GB Aviation. I was there recently and there is still a good stock of hardware for sale, and probably at prices not seen for 10 years or more. If Rodney is out of stock, ask him to get things in from the wholesaler EDMO.

 

7 hours ago, skippydiesel said:

Still listed as AN in the AAE Catalogue,

Yes, a lot of sellers keep using the AN designations because old habits die hard. It's not wrong. The items are exactly the same, and made to the same specifications.

 

Definitely be careful of the flaring tool as mentioned. The flare angles are different from automotive fittings. This is a diagram of Spec MS33584

[skippydiesel]

2 hours ago, IBob said:

Does the booster pump not have an internal (non return) bypass, or some arrangement that provides that function, Skippy?

At this stage (further investigation will take place when aircraft is returned home to my workshop) I doubt there is an internal bypass (its a Facet Cube but I don't know which model,

 

5 hours ago, rgmwa said:

Make sure you get a 37 deg flaring tool with AN fittings, not the standard automotive one.

I count about 12 variants) until I am in a position to remove a few bits & pieces and can read the part number.

 

My Sonex/Rotax experiences low fuel presser at max power (mainly TO & Climb) - I have made some changes with some improvement but not completely eliminated the problem - the Facet, being in line with the mechanical pump, may be acting as a restriction, hence the idea of putting in a bypass.

 

Rotax recommend a boost pump by-pass circuit - I don't know why this was not done by the first builder (a meticulous builder, with some novel ideas,  he like the rest of us  can err on occasion).

 

As part of the plumbing upgrade it may be that a higher flow/pressure Facet pump could be installed, if the existing one is found wanting.

 

The low fuel pressure is not the only problem - the header tank is not plumed in before the boost pump, so can only be used in cruise/taxying - I wish to change the arrangement, so that the header is used for all modes of operation (main tank), with the wing tanks acting as secondary/reserve supply (feeding the header rather than direct to the engine). I would not be removing the pilots option to fly of the wing tanks if so desired.  I see this as a simplification and therefor a safety enchantments. The plumbing to achieve this, is conceptionally simple but may be a little more complex in execution (purchasing the correct parts will go a long way to making it simpler hence my desire for hand holding).

[skippydiesel]

5 hours ago, rgmwa said:

Make sure you get a 37 deg flaring tool with AN fittings, not the standard automotive one.

Do you happen to have the flaring tool that I can borrow/hire/purchase?

[skippydiesel]

6 hours ago, Marty_d said:

I put metal fuel line in mine, bought a little beading tool from Aeroflow - AF98-2020 - PIPE BEADING TOOL SUIT 3/8" 

That allows you to make your own barbs at the end of the line,  then hose clamp regular fuel line to it. 

Great idea Marty - would make rubber hose fitting very much more secure.

 

At this stage I am hoping to do the whole system in metal (keeping faith with the first builder).

[old man emu]

8 hours ago, skippydiesel said:

At this stage I am hoping to do the whole system in metal (keeping faith with the first builder).

Design decisions are made for considered reasons. Would "rubber" hoses be more or less likely to suffer damage from rubbing or vibration? Is there a fire risk that metal would provide some resistance to?

[skippydiesel]

3 hours ago, old man emu said:

Design decisions are made for considered reasons. Would "rubber" hoses be more or less likely to suffer damage from rubbing or vibration? Is there a fire risk that metal would provide some resistance to?

Rubber hose systems, I am very familiar with & would find easier BUT that's not what I have in this aircraft, so until frustration gets the better of me, I am going with the alloy tubing.

 

The modifications are logical and simple in concept,  its the application that will test me - First with ordering the correct imperial parts/joiners,  then with installation (will order extra tube to allow for cock ups!)

[facthunter]

On your non return Valves stick with that as the system is safer and you will be safely able to get the last drop out of each tank with all pumps on and no air will enter the system. I don't like the idea of flaring aluminium. I reckon it would be too susceptible to cracking. Brake systems are steel and the flares are doubled back for strength. The special  design of the  threaded nipple prevents loads near the flare.  Vibration may be a concern and chafing on long runs. Nev

Edited May 3, 2023 by facthunter

[IBob]

A sketch/diagram would probably help the conversation here.
I don't understand how non-return valves would enable each tank to be emptied , with no risk of air.
And I don't know what sort of non return valve allows free flow in the forward direction without a throttling effect: in water reticulation, that would be some sort of swing valve, which relies (in small part) on gravity and must be installed right side up. Is there another sort of valve, more suitable for aircraft use?

[skippydiesel]

This is from the Rotax 912  installation manual - 7 is the Boost Pump. -  8 is the bypass with Non return Valve

 

[old man emu]

2 hours ago, skippydiesel said:

First with ordering the correct imperial parts/joiners,

Ignore the measurement system  These parts are made to a standard. All you have to do is order the part by its designation, whether that be AN nnn-x, or MSnnnnnn, or even NASnnnnnn. 

 

It seems that the designation of aerospace components has changed again. This chart can help decipher designation codes: https://bandemfg.com/conversion.html 

 

So a the part called for in your manual is AN827, which changed its name to MS24396 and later, as it might be called for in a design done today, AS1036.

 

The 3/8" aluminium fuel line can be obtained from https://aeroflowperformance.com/af66-3000-3-8-alloy-hard-line-9-5mm, but Supercheap has it much dearer.

[facthunter]

Plenty of aircraft have them. The  pump cavitates when the tank is empty and positive pressure from the other pump keeps the valve closed till it too cavitates.  but then both tanks are empty and you are out of fuel, which has to happen when the tanks are empty.  Other set ups allow air in or inadvertent fuel transfer.. Plenty of multi tank planes run out of fuel with fuel remaining due bad management because of inadequate knowledge of the fuel system.  Nev

[facthunter]

THAT fuel circuitry is not what I referred to.. Multi tanks with each having a pump and NR valve in or near the tank serves a different purpose. That of keeping air out of the system.   Nev

[IBob]

Thanks Skippy. I have a Facet Cube and no external bypass to that, so the Cube must allow free flow when not running: at a guess (and it is only a guess) perhaps when powered off the internals park themselves so as to allow free flow?

A minor detail with reference to your above diagram: ICP run the fuel pressure gauge via a small orifice, same as the return line. Presumably to limit the amount of fuel dumped in the cockpit if the gauge or plumbing spring a leak(?)

[facthunter]

Oil Pressure gauges  do that as well to limit the oil loss if the line breaks. That's one of the reasons Gipsy Majors have the oil pressure register so slowly. Nev