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Fuel Flow sensor Install

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8 months 10 hours ago #18783 by Rotax jack
Fuel Flow sensor Install was created by Rotax jack
I want to install an FT-60 fuel flow sensor on my Rotax 912ULS. My concern is caring for the beautiful hose that Rotax provided between the engine driven fuel pump and the carburetors. What is the recommended method of installing the FT-60?
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8 months 3 hours ago #18785 by Roger Lee
Replied by Roger Lee on topic Fuel Flow sensor Install
The FT60 should be in the supply hose not the out pressured hose. It should be horizontal for 6" on each side and have a fine mess filter before the FT60. Google FT60 installation instructions.

static1.squarespace.com/static/5282b286e...80/FT_60_install.pdf

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell

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8 months 1 hour ago #18787 by Bill Hertzel
Replied by Bill Hertzel on topic Fuel Flow sensor Install
912uls engines are now supposed to utilize a restricted flow, Fuel Return line, to purge vapors.
You will also need a second flow meter in the Fuel Return Line to measure fuel that was not used by the engine.
Otherwise, the measurement will be falsely high.
More fuel circulates through the fuel lines than the engine actually uses.
The Flow Meter will need to subtract the Return Flow from the Gross Forward flow to compute the Net Flow to the Carbs.

This is a common configuration for the 914, 915 and the 912is. It is now Required/Highly Recommended for All 912 series engines.
See the 912 Installation Manual Section 73-00-00, Page 3

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7 months 4 weeks ago #18788 by Roger Lee
Replied by Roger Lee on topic Fuel Flow sensor Install
Hi Bill,

Do as Flight Design did with there's. Put the return line in downstream of the transducer. You would only need two of these if you put the return line back upstream of the transducer.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell

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7 months 4 weeks ago #18790 by Bill Hertzel
Replied by Bill Hertzel on topic Fuel Flow sensor Install
Roger,
Re-read your last post.
I think you got an "Upstream/Downstream" and a "One/Two reversed. ;)
If you put the Transducer Downstream of the Return Line, you would only need One.

The installation Instructions suggest installing it "Between the Engine driven pump and the Carburetor".
The Specs quote a 100psi Working Pressure.
They have no restrictions in placing it in the High-Pressure, Out-Flow side of the pumps.

Jack,
It will need to go After the Fuel Pump and the Return Line but Before it splits to the Carbs.
And, Yes! You WIll be cutting those pretty Hoses. :ohmy:
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7 months 4 weeks ago #18795 by Roger Lee
Replied by Roger Lee on topic Fuel Flow sensor Install
Yes your right. Downstream of the FT60. Like on a Flight Design. The fuel goes through a fine filter then the FT60, then through the gascolator and up to the pump. Then the
re-circulation line goes back down to the top of the gascolator which is downstream of the FT60. So all the fuel only passes through the FT60 one time. The re-circulated is is only accounted for that one time.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell

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7 months 4 weeks ago #18802 by Rotax jack
Replied by Rotax jack on topic Fuel Flow sensor Install
Roger,
Which "fine filter" do you recommend? Placing the FT-60 before the gascolator means the fuel pressure at the FT-60 entrance in due to the fall from the High wing tanks plus the suction from the fuel pumps on the output side of the FT-60. Correct?

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7 months 4 weeks ago #18803 by Roger Lee
Replied by Roger Lee on topic Fuel Flow sensor Install
Most any fuel filter you would use on an aircraft is fine. The reason to put the filter before the FT60 if to keep debris out that may clog or restrict its flow.
Something like a 10 micron, but it doesn't have to be exact. Just something before the transducer.

Roger Lee
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Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell

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7 months 4 weeks ago #18804 by Bill Hertzel
Replied by Bill Hertzel on topic Fuel Flow sensor Install
Agreed!
Any filter will do the job.
The flow meter is a miniature paddle wheel.
As the fuel flows, the circuitry counts the revolutions. 68,000 per gallon.
The mechanism is built like a fine watch, so any dirt big enough to see is too big.

The sensor can measure flow rates approaching 100 gallons/Hour
Do NOT blow into it to see if it is working.
A light breath from a foot away will make it spin.
Most normal individuals can muster a peak breath flow rate exceeding 100 Gallons/Minute!
Extremely Overspeeding the tiny jeweler's bearings in the sensor.

As tempting as it is to try... Don't do it!

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7 months 3 weeks ago #18813 by DHeal
Replied by DHeal on topic Fuel Flow sensor Install
I have heard that fuel filters with "paper" elements are inappropriate for use with gasoline containing ethanol.

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7 months 3 weeks ago #18816 by Pacheco
Replied by Pacheco on topic Fuel Flow sensor Install
True

Ethanol contains water that cause the filter to clog

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7 months 3 weeks ago #18824 by jiott
Replied by jiott on topic Fuel Flow sensor Install
A couple of things:
1- It was strongly recommended to me that the FT-60 not be mounted on the engine due to heat and vibrations. I mounted mine in the cockpit in the fuel supply line.
2-Yes it measures total flow including bypass flow. I did not want the expense and complexity of using two flowmeters as was suggested, so it was a simple matter to recalibrate my pulses/gal "K" factor to give an accurate reading at cruise rpm. I manually measured my actual fuel used for a straight and level x-country trip and compared this with the FT-60 reading, which gave me a % to modify the "K" factor. Admittedly, this only gives an accurate reading when cruising at the rpm used for calibration, but that is all I really care about anyway.
3- I did not use a fine filter ahead of the FT-60, just the coarse strainers in the wing tanks. My fine filter is ahead of the fuel pump. This system has been working fine for 600 hours. If you look thru the hole in the FT-60 and the little paddle wheel, you will see that there is actually quite a large area to pass particles of fairly large size.

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7 months 3 weeks ago #18831 by Bill Hertzel
Replied by Bill Hertzel on topic Fuel Flow sensor Install

David HEAL wrote: I have heard that fuel filters with "paper" elements are inappropriate for use with gasoline containing ethanol.


Water in Diesel fuel causes issues because there is no Ethanol to dissolve the water.
Algae can grow in the water and clog the filters, Paper or otherwise.

The alcohol in MoGas dissolves any water up to ~1/2% of the tank. (~6oz per 10 gal)
This water harmlessly passes through the engine in the same manner as the water that is dissolved (evaporated) in the air used by the engine.

250 million U.S. Automobiles use Paper Fuel Filters with Gasoline containing Ethanol every year without issues.

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7 months 3 weeks ago #18836 by RobSeaton
Replied by RobSeaton on topic Fuel Flow sensor Install
Bill, I have learned that automobile comparisons are tricky. You do have to be more careful with aircraft as you dealing with altitude, longer storage times and aircraft are often built using a mixture of technology such as fuel components and materials, possibly un-tested in combination with each other. Autos are designed and tested as a complete package.
So paper filters have been proven to be a problem in aviation and should be avoided.
But can you even tell if it is paper? the Rotas 912iS fine filter is a composite material but it sure looks like paper....

Roger, I would not recommend an inline 10 micron filter for the carby engines; this is much too fine and due to the very small surface area of an in-line filter it can can plug up almost immediately with crappy fuel use.

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7 months 3 weeks ago #18841 by Roger Lee
Replied by Roger Lee on topic Fuel Flow sensor Install
Hi Rob,
"Roger, I would not recommend an inline 10 micron filter for the carby engines; this is much too fine and due to the very small surface area of an in-line filter it can can plug up almost immediately with crappy fuel use."

You're probably right. I see some use 40-70 micron.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell

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7 months 5 days ago - 7 months 5 days ago #19143 by Ed L
Replied by Ed L on topic Fuel Flow sensor Install

Roger Lee wrote: Yes your right. Downstream of the FT60. Like on a Flight Design. The fuel goes through a fine filter then the FT60, then through the gascolator and up to the pump. Then the
re-circulation line goes back down to the top of the gascolator which is downstream of the FT60. So all the fuel only passes through the FT60 one time. The re-circulated is is only accounted for that one time.


Hi Roger

New guy here, with a 912ULS in a Magni M-16 gyro on its way here from Italy. I'm wanting to put in fuel flow, e.g. with an MGL Vega, and am trying to make sure I do this right.

I THINK I understand your answer and want to make sure I don't do something stupid. To confirm, that means it is OK to put the return line directly into a tee between the FT60 and the electric and mechanical fuel pumps (and past/downstream of the fuel filter)? The return line doesn't need to be vented to atmospheric pressure or anything? Seems like if the return line had pressure while the primary line didn't, the fuel would be able to flow back through the transducer and filter into the tank, so that would seem to be OK.

I know the FT60 install instructions referenced in one of your earlier posts specifically says the 912 should have a second FT60 for the return but my guess is it would be a bear trying to accurately calibrate K factors for two transducers like that. If plumbing the return basically into the fuel pickup line after the filter but before the pumps as I think you propose works, that would seem to be ideal. I just want to make sure it wouldn't result in flooding the carbs or some other unexpected outcome because the return line is now plumbed directly into the circuit, albeit on the negative/suction side.

Also, you had said earlier they need to be mounted with 6" of HORIZONTAL run on either side of the FT60 - is that true? The install sheet says they need to be STRAIGHT for 6" but didn't specify orientation.

Thanks!

/Ed
Last edit: 7 months 5 days ago by Ed L.

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7 months 5 days ago #19149 by Roger Lee
Replied by Roger Lee on topic Fuel Flow sensor Install
Hi Ed,
So long as the return line is downstream of the FT60 then you don't need a second FT60 because the fuel has been accounted for once and not coming back through the FT60 again. If your return line is upstream of the FT60 then you would need a second one.
The idea of the 6" straight is to try and keep air bubbles and vapor from influencing the transducer.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell
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3 months 1 week ago #20139 by bushwalker
Replied by bushwalker on topic Fuel Flow sensor Install
Hello!

Are you speaking about applying that thing: appretailor.com/accessories/2/ PN: 10143?
Found it on forum: dynonavionics.com/cgi-bin/yabb2/YaBB.pl?num=1165011860

I have a rotax 914, and want to install ft-60 transducer. Installing two of them to the supply and return line with a ffdm-1 differential module is too expensive, so I search the variants.

Another variant is to install transducer to a carb fuel line between the fuel divider and stbd carb. And just multiply the flow by 2. But it is not recommended to install ft-60 ner the engine.

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3 months 1 week ago #20156 by jiott
Replied by jiott on topic Fuel Flow sensor Install
I have the FT-60 installed on my 912uls in the fuel line from header tank to engine. Its under the seat in a nice cool vibration free area. It does measure the sum of engine fuel + return fuel, but this has not been a problem for me. By far, most of your flight time is in cruise mode, so I just calibrated the "K" factor to give accurate fuel flow to the engine only at cruise. Here's how I did it: On a cross country of about 100 miles I started with fuel tanks topped off full. At the destination I filled the tanks to the top and recorded the gallons and the exact time of the flight in hours. Gallons/hours = average gal/hr and knowing the exact actual fuel burn I could compare this with the indicated fuel burn from the FT-60. Of course the indicated fuel burn was more than the actual because it was also measuring return flow. I then just reset the "K" factor using the ratio actual gallons/indicated gallons x original "K" factor = new "K" factor.Its been giving accurate results ever since. If you spend a lot of time idling or taxiing, or a lot of time climbing or descending of course the readings will be less accurate. I find I depend on the FT-60 readings mostly on longer x-countries rather than on short hops.
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3 months 3 days ago - 3 months 3 days ago #20253 by Thermalbug
Replied by Thermalbug on topic Fuel Flow sensor Install
I too am installing an FT-60 on my Rotax 912 S. My Europa Monowheel has a return line. I am going to try and install just 1, FT-60 and see if it works for my needs. Big question here; Did anyone try to move their tank return line ahead of the FT-60 and put the FT-60 just before the Carburetor split (T-line) to measure only fuel going to the carbs as Roger Lee suggested? I don't want to have to buy a second transducer if I don't have to. The FT-60 manufacturer says we do need two sensors but that seems mighty convenient for them to sell $250.00 more worth of a sensor. I have included a sketch of Roger's idea for clarification. A picture is worth a thousand words and fuel for many more questions and critiques. Thank for any help you can give us.

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Last edit: 3 months 3 days ago by Thermalbug. Reason: Answered my own question of if I had a return line.

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