Fuel Flow on Rotax 912/914

[Thomas_Schaad]

I was reading in several topics about installing a Flowscann in to a installation with the Rotax 912/914 engine. Obvioulsy several collegues are concerned about the possibility to install the fuel flow feature due to the return line. Obvioulsy some of you even considered a second flow scann, that has to go then trough a Matronics unit.

This is all not necessary, as Rotax does offer the solution for this problem. I just had the return line installed in my Pulsar yet and it works perfectly. What you need is the right fuel devider for. This is :

Rotax P/N 10143

What I do not know, is if this part is available all over the world. If not, feel free to call the distributor for Germany and Switzerland. This is

Franz Aircraft Engines
Am Weidengrund 1A, D-83135 Schechen Germany
Tel. +49-8039 9035-0  Fax +49-8039 903535
info@franz-aircraft.de
www.franz-aircraft.de

This devider is normally clamped on the tube that equalises the carburators and works as follows:

- Fuel comes from the pump and enters the first section, one part goes in the returnline, the other part leaves the devider again
- The fuel which left the devider is now on a loop, going trough the flowscann, before entering the second section of the devider
- Trough the second section the fuel is now sent to the carburators. Here is also the hook up for the preassure sensor.

If you need help on this, feel free to contact me. Good luck and

Kind regards

Thomas

 

[Simn_Smith]

Thomas,

This is fine for the 912 and 912S but will not work on the 914.

 

[Thomas_Schaad]

Simn,

I think it does work with the 914 as well. How the fuel devider works, it's more a question of where the return line starts than anything else. But if you want to buy the part, you will most probably have to call a Rotax dealer, then you make sure.

Best regards

Thomas

 

[Simn_Smith]

On the 914 the fuel goe from the pumps to a fuel regulator mounted on top of the airbox. This maintains the fuel pressure to the carbs at 2 tp 5 psi above airbox pressure. The excess is then returned to the tank. Return flow to the tank is around 25gph.

 

[lucaberta]

Hi all,

wouldn't it be easy to just install one single Floscan on either carburator, so after the fuel spider, and simple double in software the reading?

This is the way the flow sender is mounted in my Pipistrel Virus with an 80HP 912UL, the Brauniger MFD takes care of doubling the flow so the actual value less the return flow is deducted from the fuel quantity in the instrument panel.

Not sure if Dynon provides the possibily to double the flow count in software today. Would be a plus for the Rotax installations, saving quite a few bucks on the Matronics unit or the newer fuel spider mentioned by Thomas.

BTW, for those who are curious about the fuel spider p/n 10143 mentioned by Thomas, here is a link:

http://www.franz-aircraft.com/Rotax/Kraftstoffverteiler10143.htm

A crude translation from german is here:

http://translate.google.com/translate?u=http%3A%2F%2Fwww.franz-aircraft.com%2FRotax%2FKraftstoffverteiler10143.htm&langpair=de%7Cen&hl=en&ie=UTF-8&oe=UTF-8&prev=%2Flanguage_tools

Ciao, Luca

 

[Simn_Smith]

The spider will work fine on a 912 or 912s and there is also a diagram in the EMS manual (at least there is one in the D180) of a suitable method of plumbing a single sensor for these engines.

The fuel lines frol the regulator to the carbs on the 914 are small bore (about 1/8") and made of metal (maybe stainless steel). I would not want to risk upsetting the balabce of the carbs by fitting something to only one of them.

 

[lucaberta]

The spider will work fine on a 912 or 912s and there is also a diagram in the EMS manual (at least there is one in the D180) of a suitable method of plumbing a single sensor for these engines.

true, seen the diagram but my current installation has a 4-way spider, so I would need to modify the fuel lines adding the "restrictor", then adding a fuel line with the fuel flow sensor between the "restrictor" and the spider.

Would the spider be the same one used today, with one output port closed? What kind of device would this "restrictor" be? Any Rotax p/n? Or is not a Rotax part?

The fuel lines frol the regulator to the carbs on the 914 are small bore (about 1/8") and made of metal (maybe stainless steel). I would not want to risk upsetting the balabce of the carbs by fitting something to only one of them.

very good point. Luckily my Pipistrel Virus barely uses the 80HP provided by the 912, I mostly run it between 4200 and 4600 RPMs anyway...

Cheers, Luca

 

[Simn_Smith]

 What kind of device would this "restrictor" be?  Any Rotax p/n?  Or is not a Rotax part?

The one used by Europa in the 912 and 912s installation (see http://www.europa-aircraft.biz/pdfs/912xs.pdf chapt 6 for details) is made of ali and is a push fit into the 6mm hose.  It is about 8mm long and has a bore through the centre of about 0.2mm.  I don't think it is a rotax part.

 

[iceman]

I got it !! This works like a bomb. You take your supply coming from the fuel pump to a spliter. (4 Way) - 1 Going to the fuel pressure sensor , 2 Blocked , 3 Goes to the return line , 4 Goes to a two ways spliter via the fuel flow sensor. At the second spliter (2 way) you split it 1. to the left carb and the other to the right hand card. You can view a pic of the setup on my aerie at the following address :

http://picasaweb.google.com/freewillyblue/FuelFlowProblemRotax912/photo#5041099260475145938

I have tested all. Run the tanks right down to empty and all the sensor work fine. The fuel flow indicates 100%. Hope this helps.