was wondering if the shut off valve can be after the fuel pump or does it have to be between the uat and fuel pump .
thanks
Arden

Arden,

After the fuel pump and before the final filter is where it needs to be.

Cheers,

Dick
England

Dick
the jetcat manual shows the safety valve after the filter and kerosene shut off valve but on the bvm uat instruction it says to put the safety valve is located between uat and fuel pump which is the way i did it on my bvm p-80
thank you
Arden

Actually, the best place for the shutoff is before the pump... Should you have a runaway pump (ecu failure) and it runs at full pressure, instant shutoff at the valve could burst a line (has happened!). Much safer to kill the supply than the pressure

Hi Todd,

Yes, that's a good point...but in those circumstances, I'd be inclined to kill the pump supply (ie turn the ecu power off) in the first instance anyway!

I prefer to put the tap after the pump so there's less chance of air ingress due to suction drawing air past the seal (unlikely, I know, but worth a thought). Whatever you choose Arden, put the filter last in the line (no point in having it otherwise!).

Cheers,

Dick
England

Dick,
Understood BUT, having seen an ECU fail and the owners immediate response being to shut the fuel down. In doing so, the line burst or popped out of the fitting, soaking the plane with fuel.
I have always placed my shutoff ahead of the pump, never had one leak...

The location of the fuel shut off valve is only as good as your ability to reach it when needed. Once the jet is buttoned up and on the runway, or in the air, it is only along for the ride (unless you have a servo to close it).

If it is a Festo type ball valve, it should always be on the pressure side. If it has barbed fittings (and is safety wired, it can go on either side of the pump.

Wayne, did u mean that festo type should go on pressure side ?? seems that a less sturdy connection might come apart on pressure side and would be more reliable on supply side??

As far as "buttoned up and only along for the ride" I was wondering this yesterday. If you need an emergency shut off and your canopy is screwed down and the turbine is running it will take awhile to get to the Festo ball valve.

Is there a problem (other than what Todd said about being on the "pressure" side of the pump) with having an extra Festo ball valve at the back of the plane (out in the open) in the fuel supply line before it gets to the turbine? That way even if it is "all buttoned" up a person can still quickly shut the fuel off to the engine knowing though that if there is a fire back there you may or may not be able to get to the valve.

Thoughts?
Don

I prefer to put it between the UAT and the pump. This keeps the wear and tear of fueling and defueling pressures off the pump and its seals. I have had a few pump leaks in the past, and it was always on the pumps where the shutoff was downstream from the pump.

BTW, you can see the leak coming, as the first symptom is an air bubble forming in the line between the pump and the UAT when you are defuelling.

Of course, Wayne makes the best point. It has to go somewhere easily accessible, and that is the first consideration.

Here is my valve in the Hawk, easy to get to. As you can see the pump is buried under the tray an the fuel lines are covered by the smog and fuel tanks.

carlos
did you install after the pump and filter, that looks like the small size festo not the size that comes from the uat to pump i was planning to put it in the same area as you did but i was reading the instruction on the uat and bvm says to put it between the pump and uat so that is the reason for this post and i see it to concern others too it is great to be able to help each other because we all want to succeed. did you get the hawk airborne yet...............
later
Arden

CARS !!

Dude, fess up. U only weighed in on the topic to show off that masterful organisation of your lines, right?

Glad u did!

Impressive attention to detail. I hope my boomer comes outhalf as nice.

I put it between the UAT and the pump as well. I don't like pressurizing the system during fill up. You don't have to use a festo, that little barbed ball cock will do fine.

Here in Australia we must have a servo controlled shut off valve. We must demonstrate this to the inspector before we get the "Permit to Fly" signed.
You can have the model "buttoned Up' and still shut off the valve. I have mine between the pump and the engine, the servo will turn the Festo Tap OFF, but you need to manualy turn it ON. I have the servo wheel facing the tap with a 4.40 screw that pushes the taplever.

Works for me

Tom,
Do you have a picture of your setup by any chance?
Don

Hi Guys,

there are all sorts of reasons to place the shut of valve before or after the pump. Personally unless you can reach it easily without unbuttoning the aircraft then it is usless except in the fuel filling stage, to prevent kero from entering the engine.

The foolproof way is to interrupt one fuel pump wire( positave or negative doesn't matter) fuel pump wire with a small micro switch , servo operated on a separate channel, therefore if it is all going pear shaped you can flick a switch and shut the pump down . the rest of the electronics then take care of themselves. I mix this to my throttle trim, this way you never forget to turn it on.

Rgs

Norm T

An engineer whom I respect said that festo fittings are made for pressure applications (actually designed for air). Some folks have used them on the suction side, but I have seen some installations leak bubbles. I've always put mine down stream, and they have always worked for me.

Some good points made about protecting the pump during fueling, though......

Tommy, I'd like to see your servo powered shut off. Something I've wanted to do, but could never figure out the linkage geometry......

Then only time that I can think when the shut off valve is useful is when I'm about to refuel the model and this is because it will prevent fuel going into the engine if the selenoid was to fail or remain in the open position, other than that I can not get to it in time for any other reason and if I get a hot start the thing that I do is to shut off the engine via the trim.

So for me, I choose to have my shut off valve where I can get to it to turn it to the off position right after I have removed the cannopy the rear hach and have shut down the engine to preven fuel to pass during refulling.

In my Kangaroo ( my first jet and instal ) I have my shut off valve between the UAT and the pump, I haven't got a leak in this instal been two years old by now, I have learned here on RCU the the Festo fittins and valves where designed to be use under pressure not succion, it worry me in the begining but I never got a leak on the Roo instal, never change it but now days as you can see I prefer to intal my Festo valves on the pressure side and yes I have used the other valve, the one with barbs lots of times.

Highhorse

Thank you, for some reason I can't instal any other way, it took me about one year and about 5 instals to learned this way, I have a friend that has a Boomer and since I was his jet instuctor part of his training was to redo his instal in the boomer 3 times before I was satisfied with it. Need an instructor????

Hi Synthetic,

I make a small ply plate, attach the Festo Tap with a bracket (I think I got it from Dreamworks), and attach the servo with good servo tape. Drill a hole in the wheel to fit a 4.40 bolt. Make it just far enough out to touch the tap near the end.

It does not need to be aligned perfectly but try to get it close.

The pics should explain it all.

You can turn the tap on only by hand, but you can turn it off with the servo or by hand.


I use a Hitec servo so I can set the end points. I guess you could do it just as well with the radio.

I attach the plate to the side with velcro. This is in my Turboprop Extra

Regards

Arden, not yet but soon possible by woodland ( 3 weeks ) I got under my belt 2 F-16, 3 or 4 Rafales, 2 Hawks, 1 Cermark Viperjet, 1 Kangaroo, 1 yellow F-16 and possible something else that I can't remember right now and all these jets had the shut off valve just before their engines, all of them and the ones in the near future will too ( I got an F-16 and another Hawk to do soon ).

Synthetic, I sometimes fly with Tommy & this is my setup. The valve is switchable from the transmitter & shuts off when the failsafe operates. Mine is fitted between the solenoid & the engine. - John

My Cutoff switch is also the low throttle trim switch. So one switch puts the throttle into low trim and operates the valve.