Jet Central Rabbit Kerostart Fuel System Installation
07-16-2015, 12:22 PM
#1
Jet Central Rabbit Kerostart Fuel System Installation
I'm looking at the kerostart fuel system installation diagram for my Jet Central Rabbit. The diagram shows the fuel filter downstream of the 'F' (engine fuel feed) solenoid. The Festo 'T' fitting for the branch line to the 'K' (start fuel feed) solenoid is after the fuel pump, but prior to the F-solenoid. This setup will deliver unfiltered fuel to the engine start innards. This doesn't seem right to me.
In the JetCat engines I've installed, their diagrams have the fuel filter after the fuel pump prior to any solenoids. The idea, as I understand it, is to catch any debris if the fuel pump internal mechanisms start coming from together to apart. In the Rabbit diagram, the engine fuel feed is protected, but not the start fuel feed. Seems the fuel filter should be prior to the Festo 'T' so that the kerostart side is protected, too.
I've never heard of any need to protect the engine fuel feed from a solenoid issue (both Jetcat solenoids are downstream of the filter), but even if that is the logic behind the Rabbit diagram, again, the kerostart side is completely unfiltered. What am I missing here?
Also, the Rabbit fuel filter is a clear Festo type, not the silver tank/canister JetCat type. Is this anything to be concerned about?
Oh, one more thing, I did notice another difference between the Rabbit and JetCat diagrams: Jet Central puts the manual fuel shutoff prior to the pump; JetCat has it after the solenoid and prior to the engine. After searching and reading here, it seems like where to locate the manual shutoff valve in the system is a point of debate. I've always done it the 'JetCat' way and put it near the engine (heard there's less fuel in the line to consume this way), but I've always wondered just how am I going to get to it if flames are in the engine bay. After reading the debate on this, I'm going to switch and put the valve prior to the pump and away from the engine bay.
Sluggo
In the JetCat engines I've installed, their diagrams have the fuel filter after the fuel pump prior to any solenoids. The idea, as I understand it, is to catch any debris if the fuel pump internal mechanisms start coming from together to apart. In the Rabbit diagram, the engine fuel feed is protected, but not the start fuel feed. Seems the fuel filter should be prior to the Festo 'T' so that the kerostart side is protected, too.
I've never heard of any need to protect the engine fuel feed from a solenoid issue (both Jetcat solenoids are downstream of the filter), but even if that is the logic behind the Rabbit diagram, again, the kerostart side is completely unfiltered. What am I missing here?
Also, the Rabbit fuel filter is a clear Festo type, not the silver tank/canister JetCat type. Is this anything to be concerned about?
Oh, one more thing, I did notice another difference between the Rabbit and JetCat diagrams: Jet Central puts the manual fuel shutoff prior to the pump; JetCat has it after the solenoid and prior to the engine. After searching and reading here, it seems like where to locate the manual shutoff valve in the system is a point of debate. I've always done it the 'JetCat' way and put it near the engine (heard there's less fuel in the line to consume this way), but I've always wondered just how am I going to get to it if flames are in the engine bay. After reading the debate on this, I'm going to switch and put the valve prior to the pump and away from the engine bay.
Sluggo
07-16-2015, 02:24 PM
#2
Join Date: Nov 2003
Location: Mexico CityD.F., MEXICO
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Hello Sluggo
First of all, please excuse my english
There are several reasons we prefer the filter after the pump, and only at the primary fuel line, the most important one is that there is a small restrictor for lubrication that can get clogged easily, we also prefer the filter to be at the pressure side and not at suction side, filters tend to catch air bubbles and let them go suddenly, turbines can take bubbles but not the fuel pump, the fuel pump normally is protected by the UAT, but the pump can produce small debris over time and thats what we intend to catch, the burner is not be affected by small/medium debris
The Festo filter is not supplied by us, we supply the Hangar 9 gold filter, a lot of people are using Festo filters with good results but I don't recommend it before the pump
People does not like the shut off valves in suction side but we have tested and we now recommend it to be prior the pump, the most important thing is it to be handy
Hope this helps
First of all, please excuse my english
There are several reasons we prefer the filter after the pump, and only at the primary fuel line, the most important one is that there is a small restrictor for lubrication that can get clogged easily, we also prefer the filter to be at the pressure side and not at suction side, filters tend to catch air bubbles and let them go suddenly, turbines can take bubbles but not the fuel pump, the fuel pump normally is protected by the UAT, but the pump can produce small debris over time and thats what we intend to catch, the burner is not be affected by small/medium debris
The Festo filter is not supplied by us, we supply the Hangar 9 gold filter, a lot of people are using Festo filters with good results but I don't recommend it before the pump
People does not like the shut off valves in suction side but we have tested and we now recommend it to be prior the pump, the most important thing is it to be handy
Hope this helps
07-16-2015, 04:24 PM
#3
Juan, placing the fuel filter AFTER the pump is not the issue. I understand that...to be clear, no one is saying the fuel filter should be placed BEFORE the pump. I've always paced the fuel filter after (downstream of) the fuel pump.
My question is why Jet Central shows the fuel filter after the 'F' solenoid. This location of the fuel filter does not provide filtered fuel to the start/K-solenoid. It is my opinion, and this is in accordance with JetCat's installation diagram, that the fuel filter should go AFTER/downstream of the fuel pump, but BEFORE the 'T'. This way both the F-solenoid/fuel line and the K-solenoid/start fuel line BOTH are protected by the fuel filter.
Again, if the fuel system is plumbed per the Jet Central fuel diagram, unfiltered fuel out of the fuel pump will go to the kerostart fuel line. You say the burner is not affected by small/medium debris, but why risk any debris getting in there? What harm is there in feeding filtered fuel to both the engine and the start fuel lines? How will placing the fuel filter AFTER the pump in the main fuel line, but BEFORE the 'T' where the kerostart line branches off of the main line, cause any clogging of the small lubrication restrictor?
My question is why Jet Central shows the fuel filter after the 'F' solenoid. This location of the fuel filter does not provide filtered fuel to the start/K-solenoid. It is my opinion, and this is in accordance with JetCat's installation diagram, that the fuel filter should go AFTER/downstream of the fuel pump, but BEFORE the 'T'. This way both the F-solenoid/fuel line and the K-solenoid/start fuel line BOTH are protected by the fuel filter.
Again, if the fuel system is plumbed per the Jet Central fuel diagram, unfiltered fuel out of the fuel pump will go to the kerostart fuel line. You say the burner is not affected by small/medium debris, but why risk any debris getting in there? What harm is there in feeding filtered fuel to both the engine and the start fuel lines? How will placing the fuel filter AFTER the pump in the main fuel line, but BEFORE the 'T' where the kerostart line branches off of the main line, cause any clogging of the small lubrication restrictor?
