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Why do we need a Fuel Solenoid?

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Why do we need a Fuel Solenoid?

Old 06-29-2015, 01:41 PM
  #26  
Harley Condra
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Originally Posted by basimpsn View Post
If I remember correctly the older manual start ram engine didn't use fuel or gas solenoid.
Very true.
I had RAM 750 S/N 042 back in the day.
Air start, and separate oil tank. A 4 oz. fuel tank contained the turbine oil which was fed to the engine oil port by case pressure.
No need to mix oil in the fuel.
It did not use a fuel or propane solenoid valve.
Old 06-29-2015, 05:58 PM
  #27  
vega406
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i picked up on a Velox and a Falcon with Ram 500 and didn,t know it but hidden in the mess under the canopy there were no solenoids fuel or gas and ran fine...i did simply add one for fuel just for extra safety
Old 06-29-2015, 08:57 PM
  #28  
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There are a lot of good answers and theories here. The solenoid valves are important and needed like gunradd stated for starting purposes. The ECU commands the pump to start the fuel but it is the solenoids being controlled to pulse at a certain rate to allow small amount of fuel for ignition, then allow more for pre heat as well as the run valve will start pulsing with the start valve to regulate the fuel during pre heat and fuel ramp until it is running. I don't think a fuel pump can be controlled at such a small rate for starting purposes. The pump is pumping way more fuel than what is needed so the valves are restricting the amount supplied. Once it is running the "start solenoid" is shut off and the run solenoid is held full open with the ECU controlling the pump for full fuel delivery. The Solenoids are electro magnetic to open and they have a spring to return them closed when power is shut off to them. When you start most turbines, you hear the ticking of the valves opening & closing rapidly through the whole start process. You can manually start a propane version but even then you are opening and closing the propane valve (acting like a solenoid) to get the proper initial fire going. You don't just go wide open on the propane as it usually to much gas and won't ignite. As for a kero start version, good luck with manually trying to start that. Yes, the solenoid valves have many other benefits like many others here have stated.

Hope this helped,

Dirk
Old 06-30-2015, 07:13 AM
  #29  
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Like Flyinfool & Gary stated, I have seen many valves that were supposedly broken but actually quite the contrary, I have found slivers of fiber glass, fuel tube and most recently, appears to be algae goop from old bad fuel keeping the valve from doing its job. I know we all use fuel filters and I have no idea how this stuff gets past the filter, but I find debris all the time stuck in the valves.


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Old 06-30-2015, 03:53 PM
  #30  
Vettster
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Lets speak about runaway fuel pumps caused by a failed ECUs for a moment. If the fuel pump is a runaway and is constantly pumping fuel and increasing the engine RPMs above its rating... Is the solenoid actually strong enough to hold back all the pressure in the fuel line? Would the fuel line not pop off or even worst have a partial leak emitting fuel mist into the fuse and being ignited by the still running engine. Seems to me.. the best way to cut out the problem would be to have an electronic switch on the fuel pump that is activated by the Tx.. Not the ECU.
Old 06-30-2015, 03:53 PM
  #31  
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.......................

Last edited by Vettster; 06-30-2015 at 04:19 PM.
Old 06-30-2015, 03:55 PM
  #32  
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........................

Last edited by Vettster; 06-30-2015 at 04:19 PM.
Old 06-30-2015, 03:55 PM
  #33  
Vettster
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wow!... I see RCU is all screwed up Yet Again!!

Last edited by Vettster; 06-30-2015 at 04:19 PM.
Old 06-30-2015, 11:15 PM
  #34  
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I have read all sorts on this tread.

The valve was used because it provided automatic control over the fuel flow to the engine. Back in the day when starting manually many people had problems in starting engines and it was not uncommon to see fuselages roasted. This was normally due to opening the manual fuel valve during the start having forgotten to open it at the start. Also the starter motor needs a separate power supply and the battery may not have been freshly charged. Also people found it difficult to juggle the externally applied igniter for the glow plug, the gas supply, and electric power for the starter. By all means switch the ecu back to manual mode (the Xicoy unit can be toggled in the menu structure when the start mode is displayed). Do not come back and moan though if you toast the fuselage.

The little valve only opens when power is applied. No power and it stays shut with the spring inside. If fuel is filtered then it is very rare for valves to get stuck. on one of my planes last weekend I managed to block the vent with it on the stand and the first of the 2 tanks was pressurised, it quickly had bent sides rather than flat ones and the bung started to spray fuel out of it. I was concerned that the valve would have leaked fuel but none went through it and the start was normal. In normal use the valve should not leak fuel past it.

How many of you have ever seen a runaway pump caused by an ecu?

John
Old 07-01-2015, 03:40 AM
  #35  
Art ARRO
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John,
Several years ago I personally experienced a runaway fuel pump during a slam throttle test on a FTE-500 turbine. This was in the model, which was on the ground- fortunately. The first indication was the bubbling of paint at the rear of the fuselage. I quickly shut off the manual fuel valve (Jet Cat type) and shot a few squirts of Halon down the tailpipe quickly extinguishing the fire. When I picked up the model about a liter of kero poured out the rear of the fuselage. I later removed the turbine and sent it in for checkout and/or repair. Note that this occurrence was with an early version of the ECU and I have not experienced any problems after software upgrades. I'm strongly in favor of monitoring every start with a Start Box/ Data Terminal and having a suitable extinguisher close by. A dedicated manual fuel shut off valve is also mandatory. Anyone else care to relate their experiences with on-board fires ?
Rgds,
Art ARRO
Old 07-01-2015, 04:04 AM
  #36  
Vettster
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John.. I dont think anyone here has said they are NOT going to use it anymore..

For Kero start you absolutely need it, But for Gas start, not so much, but still is an important part and should stay. Times have evolved the turbine engines and the parts that come with it.. Sometimes you wonder if things have become un-necessary. ie..UAT I dont use that anymore

Curiosity prompted me to ask the original question... Had no Idea it would gain so much attention lol
Old 07-01-2015, 05:49 AM
  #37  
S_Ellzey
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Originally Posted by rhklenke View Post
I did not think of it that way. When I read it, the phrase "closes with loss of power" implies a normally closed solenoid valve - a fuel pump does not "close" in the normal sense one thinks of "opening" and "closing".

You are right though in that the wording is ambiguous. I don't know what the intent was when the rule was originally written, but my guess is that, since most production turbine engines have (or have had, RAMs not withstanding), a fuel solenoid, that it was intended to require them, along with a manual valve.

For my part, I have never had a failure of a fuel solenoid, but in spite of myself, I quite often forget to check the manual shutoff before fueling, and I don't think that just a stopped fuel pump is enough to keep from flooding the engine during fueling - what with the high speed fueling pumps most of us use...

Bob
As one of the authors of the regulation I can say that the intent was for there to be a shutoff valve, just stopping the pump was discussed and ruled out.

You have to remember that at the time this was written JPXs where still flying (and may still be) and they had a servo operated shutoff valve, and most of the newer engines of the day had solenoid valves. So the regulation was written to allow these to operate and set a standard for future engines. The wording was left somewhat open to allow for new technology. Had the regulation said “solenoid valve”, if someone came up with, say a piezoelectric valve, it would not be compliant.

As to run away fuel pumps, I saw one at the Mississippi event many years ago. It resulted in a fire ball in the sky. There was no ECU operated shutoff valve, so the pilot could do nothing about it. This event is one of the contributors to the regulation.

Steven
Old 07-01-2015, 06:08 AM
  #38  
Airforce7
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I've never personally had an issue with a runaway pump, but I did have an issue with the solenoid valve once. Troubleshooted for several hours and then realized I had connected the valve backwards in the JC ECU. Wasn't paying close enough attention the the wire colors and pinout text on the label.

For smoke, I definitely recommend a manual shutoff valve incase there are issues with the pump or during startup. Sometimes you can introduce to much residual smoke oil to the back of the turbine and fuselage to cause it to catch fire during startup. This was something I experienced on my old Rookie II many years ago.
Old 07-01-2015, 06:11 AM
  #39  
rhklenke
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Originally Posted by S_Ellzey View Post
As one of the authors of the regulation I can say that the intent was for there to be a shutoff valve, just stopping the pump was discussed and ruled out.

You have to remember that at the time this was written JPXs where still flying (and may still be) and they had a servo operated shutoff valve, and most of the newer engines of the day had solenoid valves. So the regulation was written to allow these to operate and set a standard for future engines. The wording was left somewhat open to allow for new technology. Had the regulation said “solenoid valve”, if someone came up with, say a piezoelectric valve, it would not be compliant.

As to run away fuel pumps, I saw one at the Mississippi event many years ago. It resulted in a fire ball in the sky. There was no ECU operated shutoff valve, so the pilot could do nothing about it. This event is one of the contributors to the regulation.

Steven
Steven,

Thanks for the clarification. I thought that the intent was for an electronic valve of some type, but I was not completely sure.

Thanks!
Bob
Old 07-01-2015, 06:41 PM
  #40  
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Originally Posted by dyuj View Post
Just wondering what its real purpose is? When the engine is not running, the fuel pump is not active. Also we shut off the valve. If the plane goes into fail-safe the pump stops working. When the engine is running.. all it does is stay in the open position

the solenoid provides a means of immediately stopping fuel flow to the turbine. shutting off the power to the fuel pump doesn't immediately stop the flow of fuel.
Old 07-02-2015, 02:39 AM
  #41  
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Originally Posted by KC36330 View Post
the solenoid provides a means of immediately stopping fuel flow to the turbine. shutting off the power to the fuel pump doesn't immediately stop the flow of fuel.
A turbine will not continue running without fuel pressure. If the pump stops the engine stops it is that simple. I have run engines many times with manual start and stopping the fuel flow stops the turbine.

Have a look at this video and the problems manually starting 6 engines but they all stop instantly when at the end of the video the fuel pumps are stopped. There are no solenoids on this plane but there are 6 manually operated valves.


https://www.youtube.com/watch?v=9NmhlhZgLjA John
Old 07-02-2015, 02:13 PM
  #42  
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Originally Posted by Jgwright View Post
A turbine will not continue running without fuel pressure. If the pump stops the engine stops it is that simple.

did i say that power loss to the pump wouldn't stop the turbine?

the question asked was what is the purpose of the solenoid, so once again, the solenoid provides a means of immediately stopping fuel flow to the turbine. shutting off the power to the fuel pump doesn't immediately stop the flow of fuel.

if you don't believe that take a fuel pump and prime it, use a AA battery and pulse the pump every 1/2 second by contacting the battery to the leads on the pump, the stream of fuel out of the pump will be a steady trickle, do the same to a solenoid and it'll be a broken stream.
Old 07-02-2015, 04:07 PM
  #43  
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Originally Posted by KC36330 View Post
did i say that power loss to the pump wouldn't stop the turbine?

the question asked was what is the purpose of the solenoid, so once again, the solenoid provides a means of immediately stopping fuel flow to the turbine. shutting off the power to the fuel pump doesn't immediately stop the flow of fuel.

if you don't believe that take a fuel pump and prime it, use a AA battery and pulse the pump every 1/2 second by contacting the battery to the leads on the pump, the stream of fuel out of the pump will be a steady trickle, do the same to a solenoid and it'll be a broken stream.
I have ran turbines for test purposes with and without the solenoid and when you hit the kill switch they shut down immediately, The solenoid does help the engine stop any quicker in my experience.
Old 07-02-2015, 08:20 PM
  #44  
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I've been running one of engines without fuel valve for over 60 flights without any issues.
It is a gas start engines and have only a gas valve.
I did have fuel valve with this engine till the valve started to limit the amount of fuel going to the engine, so the engine will start but when I try to throttle up it stops.
I removed the valve and had no issues since.
Old 07-03-2015, 02:42 AM
  #45  
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Originally Posted by xchgh View Post
Just wondering what its real purpose is? When the engine is not running, the fuel pump is not active. Also we shut off the valve. If the plane goes into fail-safe the pump stops working. When the engine is running.. all it does is stay in the open position.
Originally Posted by dyuj View Post
Just wondering what its real purpose is? When the engine is not running, the fuel pump is not active. Also we shut off the valve. If the plane goes into fail-safe the pump stops working. When the engine is running.. all it does is stay in the open position
Just wondering what its "REAL PURPOSE"behind these identical post with different user names. Advertisement, identity theft, Getting a threat posting up to 100? lol.

Last edited by basimpsn; 07-03-2015 at 02:46 AM.
Old 07-03-2015, 09:23 AM
  #46  
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Originally Posted by xchgh View Post
Just wondering what its real purpose is? When the engine is not running, the fuel pump is not active. Also we shut off the valve. If the plane goes into fail-safe the pump stops working. When the engine is running.. all it does is stay in the open position.
On a propane start engine the valve is not really needed for normal engine operation, However it can prevent fuel from getting past the pump to the engine during refueling and also if the
ECU has a malfunction and runs the pump at full blast the valve can turn of the fuel assuming the ECU is able to turn of the valve.

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