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Fuel flow sensor installation-photos

Pmerems

Pmerems

Well Known Member
Advertiser
Gents,

I installed my fuel flow sensor and thought some photos might help others.

fuel flow sensor installation.jpg


I am using a FI engine and I installed my sensor next to the high pressure electric fuel pump. Installing the sensor in this location allowed over 6" of straight tubing prior to the sensor thus meeting the straight run requirement from the sensor manufacture. In addition the sensor fit under the pump cover and no significant modifications were needed to Van's stock electric fuel pump cover kit.

I am sure others have mounted their sensor in the same location but I haven't seen any good photos of the installation.
 
nicely documented. wouldn't it be cool if you received a binder with color picts like that in the plans?
 
Wow, NICE work there.

And YES it would be extremely cool if Vans would update their plans set. How about something HTML on a CDROM. I mean, the binder and paper plans went out in 1990.

If one of us would step up to the plate and do a nice job with a plans disc - well written, thorough, LOTS of pics, all hyper-linked, it would SELL big-time I think.

Anyone feel up to the task?
 
what happens if purge valve used?

I like this set up. I have a purge valve with my AFP inj system. The fuel would register through the valve but is not really "used up" as it is returned to the tank. Do you just purge with your engine monitor/fuel computer off?
 
Nice, but...

You did a very nice job, but the recommended location for FI without a return is between the Servo and Divider. You may have significant error locating your sensor where you have it, as others have reported.
 
Anyone using a return line?

I have the SilverHawk FI as well and have plumbed a return line through the Andair duplex valve. Have any of you already done this and included a pair of fuel flow sensors?

-rob
 
Don't have a return line-flow accuracy

Gents,

I don't have a return line on the Silver Hawk FI. Don't need one per Precision and Superior.

I have read different reports of flow reading accuracy. I believe this location is as good a some of the others. Possibly when the fuel pump in on there maybe some variation but during normal engine operation with the pump off I would expect the flow to very accurate since. Flowmeters don't like turbulent flow so the straighter the run to the inlet the better.

Paul
 
This is the definitive thread on installation of a fuel flow transducer. It's all been covered in depth here:

http://www.vansairforce.com/community/showthread.php?t=11698

And to read an authoritative and truly excellent document also dealing with transducer installation I recommend this publication by JPI:

http://www.jpinstruments.com/700-800_FF_install.PDF

Some builders continue to place the transducer before the mechanical fuel pump. This is obviously not ideal for two reasons. 1. The transducer can be grossly inaccurate when the electric fuel pump is turned on. 2. It creates another system of fuel flow resistance upstream of the mechanical pump thus increasing the possibility of vapour lock.

Placing the transducer somewhere downstream of the mechanical pump is the philosophy of JPI, Advanced Flight systems, EI International, and Airflow Performance. You'd think that there might be a bit of combined knowledge between that group.

Even Dan Checkoway who mounted it in the cabin directly after the boost pump said he would not do it that way again.

But hey, this is the Experimental category. Builders can do what they like.
 
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More information

After reading the Captain Avgas's post I contacted Dan Checkoway and he sent me an email he received from Airflow Performance.

Here are the excerpts:

I have one comment, in that be cautious that installing the flow transducer on the suction side of the engine driven fuel pump or boost pump may cause vapor problems. This is due to the fact that the flow transducer has a very small orifice so that if you have this device say between the engine driven pump and the boost pump the engine driven pump must "suck" the fuel through the transducer when the boost pump is off. Since there is a pressure drop through the transducer it's possible to boil the fuel under certain conditions, hot operation/high altitude. Then of course the fuel injection doesn't work to good. We have also had some cases of locked rotors in the transducer for what ever reason, trash etc. and the result was erratic engine operation because of vapor and restricted fuel flow.

We recommend that the flow transducer be mounted in the metered fuel line (the line between the fuel control outlet and the purge valve inlet). This gives the best flow reading (flow out of the fuel controller is smooth, no pump pulses) and the fuel is always under pressure. We have had great success simply mounting the transducer using the hoses to support it. A short piece of hose (#4 firesleeved) straight fittings on each end of the transducer and clamp the hose 3-6 inches away from the transducer. This keeps the engine vibration from beating up the transducer (I have seen some installations on Pipers where the transducer was mounted directly to the engine driven pump or on the top of the engine next to the flow divider). We have used a full flow 90 deg hose fitting in the outlet side of the transducer on some installations because of clearance reasons and operation and stability of the readings was fine. Use two AN816-4-4D fittings on the transducer. We try to keep straight hose on the inlet side around 6" minimum (putting a curve in the hose is OK). I wouldn't put any 90 degree fittings into the transducer.

I will continue on to fight with my Andair valve feed lines and consider relocating the sensor as advised.

Paul
 
Wise Choice

If you need pictures, let me know. Not sure if I have them archived, but I will take the cowling off and get them for you.

Mine is "hung" off of the flow divider on top of the engine with a 4" piece of firesleeved hose. The fuel line goes straight out of the back of the Silverhawk (by the way, there are ports on the front, and back, to use) and up the backside of the engine, through the baffling to the transducer.

Accuracy is so good, it is unmeasurable, at least by me.
 
These photo appear to show a completed EI fuel flow tranducer installation using the original Lycoming supplied fuel hose. In a burst of creativity, I used a Lycoming supplied "twist type" bracket bolted to the engine sump and loosely bolted through a convenient hole in the transducer's housing to help support it. I say "loosely" because I don't want to expose the transducer to engine vibration any more than absolutely necessary and according to the instructions, a supported fuel hose is considered to be all the rigidity the transducer needs. In reality, I cut the original hose in two and I'm having Varga make up new fuel hoses because I just don't want to take any chances with so critical an application as this. Nevertheless, the photo clearly shows how simple a fuel flow transducer installation on an OEM injected engine is using IE's red cube transducer. Unlike other transducers, orientation is not a concern and mounting it between the injection servo and the flow divider is the major requirement. IE claims you can mount their transducer in virtually ANY position but doing so vertically as shown is considered ideal because doing so minimizes any chances of cavitation.



 
Rick6a said:
In reality, I cut the original hose in two and I'm having Varga make up new fuel hoses because I just don't want to take any chances with so critical an application as this.
Click to expand...

It would be interesting to know what EI thinks about aluminium fittings into the flow transducer. JPI certainly specify steel fittings. Can you explain the reasoning for having steel fittings on the hose and then attaching those steel fittings to aluminium fittings at the transducer.
 
What is the big deal with aluminium fittings ?

All the fittings around the fuel valves are the same, the body of the transducer is some sort of alloy, the fuel lines themselves are aluminium, why choose steel ?

Strikes me this is a crossover from other certified aeroplanes and is not needed here.

Paul - that is the same location we chose for or transducer, after reading all of the various arguments, it is staying there. We have enough junk under the cowling already, trying to get the transducer mounted in a better or cooler location than you already have will be difficult.
 
rvermeland said:
I have the SilverHawk FI as well and have plumbed a return line through the Andair duplex valve. Have any of you already done this and included a pair of fuel flow sensors?

-rob
Click to expand...

Rob,
I haven't done what you suggest, because currently, I do not have a dedicated return system (as you do). What you suggest is the recommendation for your fuel system design by most EFIS manufacturers. The transducer in the return stream is used to calculate the amount of fuel being returned to the fuel tank. This unused fuel is subtracted from the amount reported by the "feed" transducer.
I am seriously considering converting my system to include a dedicated return system. Last year I had several long discussions with Todd from Peterson Aviation (holders of STCs for using auto fuel in 8.5 to 1 compression carbureted Lycomings and fuel injected Continentials. Todd told me that the reason Peterson could not get STCs for FI Lycomings was because of the lack of a dedicated fuel return system in the aircraft fitted with them. He strongly suggested that a dedicated fuel return system would eliminate any chance of vapor lock when using fuel injection on our RVs.
Charlie Kuss
 
JonJay said:
If you need pictures, let me know. Not sure if I have them archived, but I will take the cowling off and get them for you.

Mine is "hung" off of the flow divider on top of the engine with a 4" piece of firesleeved hose. The fuel line goes straight out of the back of the Silverhawk (by the way, there are ports on the front, and back, to use) and up the backside of the engine, through the baffling to the transducer.

Accuracy is so good, it is unmeasurable, at least by me.
Click to expand...

I mounted mine just like Paul did and now reading everyones posts I should probably move it to get more accuracy. I am intrigued that you put yours on the top of the engine but concerned about the heat build up especially after shutdown. I also have a Sliverhawk. Any comments or concerns you have had about heat build up in this area especially for hot or warm restarts? The other thing would be to to connect it behind the rear baffle.

Thanks
 
Capflyer said:
I mounted mine just like Paul did and now reading everyones posts I should probably move it to get more accuracy. I am intrigued that you put yours on the top of the engine but concerned about the heat build up especially after shutdown. I also have a Sliverhawk. Any comments or concerns you have had about heat build up in this area especially for hot or warm restarts? The other thing would be to to connect it behind the rear baffle.

Thanks
Click to expand...

This location was suggested by a local AP and from what I understand pretty common. I looked at putting it behind the baffle first, but could not find a decent location to keep my bend radius in the fuel line acceptable, and keep the straight run suggested for the sensor. It is probably doable.
Basically, this location ended up being the only clean place for me to put it.
The top of the engine is actually a very cool place, when flying, as it is in the plenum. I have not had any issues with hot starts and I do not have a purge valve, so radiant heat after shut down, so far, has not been a problem. Time will tell. (Aprox. 85 hours flying)
 
Steel fitting reason

What is the big deal with aluminium fittings ?

All the fittings around the fuel valves are the same, the body of the transducer is some sort of alloy, the fuel lines themselves are aluminium, why choose steel ?

Strikes me this is a crossover from other certified aeroplanes and is not needed here.
Click to expand...

I remember reading somewhere - maybe it was the installation manual for my VM1000C - the fittings are spec'ed as steel because aluminum fittings can gall and jam against the alloy the Floscan housing is made of. I don't think its a strength issue as noted previous posts - everything else in the fuel system is aluminum and works fine.

Now, to royally contradict myself, I used -6D aluminum fittings on my install but used liquid thread sealant on the threads. I've tested this and got no galling or jamming at all.

Is this an art, a science, or what?! :D
 
mike newall said:
What is the big deal with aluminium fittings ?

All the fittings around the fuel valves are the same, the body of the transducer is some sort of alloy, the fuel lines themselves are aluminium, why choose steel ?

Strikes me this is a crossover from other certified aeroplanes and is not needed here.
Click to expand...


These are the advantages of steel fittings FWF.

1. Will minimise galling when screwed into aluminium threads.

2. Immune to stress failure when subject to long term vibrations.

3. Fully fire rated.

These are the disadvantages of steel fittings FWF.

1. Weigh marginally more than aluminium fittings.

2. Cost substantially more than aluminium fittings.

Steel fittings are not required aft of the firewall because this area has low vibration stresses.
 
Rick6a said:
These photo appear to show a completed EI fuel flow tranducer installation using the original Lycoming supplied fuel hose. SNIP

Click to expand...

Rick, I'm not sure whose airplane these are from, but, that fuel line is way closer to the exhaust than I'd be comfortable with. Your wording indicates it is not your plane.

Would others be worried about this? I personally would not want a line closer than about 2", more is better.
 
Alex,

Pictures can be deceiving. Here is a slightly different angle. Stock hose run, stock Vetterman exhaust.


 
Captain Avgas said:
It would be interesting to know what EI thinks about aluminium fittings into the flow transducer.......
Click to expand...
mike newall said:
What is the big deal with aluminium fittings?...
Click to expand...


For those who are truly interested, the information is quite easy to find out. Inquiring minds can either call EI's friendly tech folks toll free at (877) 318-6060 and get verbal assurances OR refer to the suggested hardware call out on page 15 in the official installation document that I linked here:

http://www.buy-ei.com/Manuals/EI MVP-50P II.pdf

;) Nuff said.
 
Increasing the safety margin

Rick6a said:
For those who are truly interested, the information is quite easy to find out. Inquiring minds can either call EI's friendly tech folks toll free at (877) 318-6060 and get verbal assurances OR refer to the suggested hardware call out on page 15 in the official installation document that I linked here:

http://www.buy-ei.com/Manuals/EI MVP-50P II.pdf

;) Nuff said.
Click to expand...

Rick Galati is to be commended for taking the time and effort to post photos of his fuel flow transducer installation and sharing his knowledge. I am sure it is a satisfactory installation and will work well for him.

However if I personally was adopting Rick's installation model I would be inclined to make a few minor ammendments in the interests of increasing the margin of safety. I note them below and state my reasons for suggesting them.

1. If at all possible, I would attempt to increase the distance between the fuel hose and the exhaust. REASON: Increase the distance from a significant heat source.

2. I would use steel fittings going into and out of the transducer. REASON: Steel has superior fatigue properties, flame resistance, and anti-galling properties. Electronics International (manufacturer of the FT-60 transducer) approves aluminium fittings but recommends steel fittings for "optimum" performance. Additionally I am not certain if there is any logic in having steel hose fittings combined with aluminium transducer fittings in that location.

3. I would fire sleeve the transducer. REASON: Fire protection and heat minimisation as well. In fact Electronics International state in their installation requirements that the transducer should be firesleeved if it is located within 6 inches of an exhaust.

But in the end we are talking here only about degrees of safety margin. I tend to think it might be advantageous to be very conservative when it comes to the fuel supply system because there is absolutely no redundancy from the fuel selector forward. In other words any point failure and the plane is coming down, or catching fire (or both).
 
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What's significant?

JonJay said:
You did a very nice job, but the recommended location for FI without a return is between the Servo and Divider. You may have significant error locating your sensor where you have it, as others have reported.
Click to expand...

I mounted my fuel flow transducer between the electric and engine pumps. I know that's not ideal, but the magnitude of the error isn't that great -- at least for me.

If I burn 30 gallons without doing any touch-n-goes and the boost pump only on for single takeoffs and landings, the totalizer says I have about 0.5 gallons less than I actually have at fill-up. If I do a bunch of pattern work with that same 30 gallons and the boost pump on continuously, the totalizer says I have about 1.5 gallons less than I actually have at fill-up.

Either way, the error is on the "safe" side and the magnitude is acceptable for me.

-Geoff
RV-8
 
Followed his example

I used the same exact location. Fits perfectly. I did read one post that mentioned incorrect readings without a return. Not sure since the sensor monitors what goes through it and I do wonder if anyone has noticed any differences that are significant.

With an estimated "just under 2 months" until finished, I am interested in the accuracy once I go wheels up.

Webb
RV7A
N32WW (reserved)
 
Here's how I'm doing it

I'm putting mine between the injector servo and the flow divider. There wasn't enough room to put the ff sensor on top of the engine so I made up a bracket to bolt it to the engine case via the sump bolts.

DSCN0005.JPG

dscn0006.jpg
 
The standard config on the RV-10 is the fuel flow is mounted after the pump and filter about 12" away. I have this setup with the Silver Hawk and have very accurate reading.


Ray
 
kcameron said:
I'm putting mine between the injector servo and the flow divider. There wasn't enough room to put the ff sensor on top of the engine so I made up a bracket to bolt it to the engine case via the sump bolts.

DSCN0005.JPG

dscn0006.jpg
Click to expand...

Kevin how has this location worked out for you? This is a really nice installation, and a very elegant bracketing solution. In particular I'm wondering if you were able to make a hose short enough from the fitting on top of the fuel servo to reach the sensor inlet as shown. Second, I am wondering if engine vibration has taken any toll on the sensor mounted as shown since at least one manufacturer recommends just supporting the sensor with hoses and no brackets. Just trying to figure out how I'm going to do it and looking for a PIREP.
 
Wow! I didn't think that anyone but I appreciated this design. Thanks for the kudos.

I used a 11" hose with straight fittings from the 90 degree fitting on the injector servo to the straight fitting on the ff sensor. The hose forms a 180 degree bend and gives a straight flow path leading into the sensor.

I've flew it all last year. It was accurate and didn't give me any problems.

Here's the best picture of it I could find:
00004.jpg


Hope that helps.
 
Fuel flow sensor

JonJay, I would really appreciate some pics of your fuel flow tranducer if it isn't too much trouble.

Thanks!
 
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