Fuel flow sensor fault

[morne75]

Rotax 912 uls.. aircraft stood for several years,fuel sensor worked fine till today..
Notice while flying that the flow sensor stop working.. when I switch my electric fuel pump on it reads for a while and then return to o flow..

Do I need to replace the unit or can I open the flow sensor too clean te inside..

Flow sensor runs of a enigma with radac unit.

[morne75]

I see on the engina the flow sensor value is set at K 7000..is this the correct setting for a Rotax 912uls..

I blew very slightly into the sensor I see its working and reading out on the enigma ,but I need to now this.. must the senior be mounte horizontal or vertical..

Thanks

[rainier]

7000 seems OK (that's the standard default setting).

Yes you can blow through the sensor no problem.

Best orientation is lying flat on its side with outlet slightly above inlet (Arrow is on top). This was the spindle rests on only one bearing and there is almost zero friction. You can experiment with this when blowing through the sender - you can hear the impeller spin.
You can open the sender (I am assuming you have the MGL flow sender) easily if you need to clean it out.

[Paul Sistern]

Just be aware that when blowing through the sender can easily result in droplets of water condensing inside the chamber and these can drag on the rotor, slowing it down. There is quite a pressure drop as you blow through the jet and that causes moisture to condense out of your breath.

Paul

[morne75]

Thank you yes its the mgl flow sensor..

[Major_John]

Hello gentlemen,
My FT-60 rotor blocked second time
It was blocked when I bought it. I was blowing but no sound. But finally I've heard the rotor sound, and FF-5 has show me the numbers.
Today the FT-60 worked first, but then FF-5 showed me zero
I took FT-60 out, blowing in, and there was no sound again.
I was blowing more and more, and finally I've heard the sound of the rotor, and FF-5 was show me numbers.
I've try to open the cover, but one screw was broking and I didn't continue.
Could you advice, why the rotor is blocking again?

[rainier]

Well the only similar case I know of dates back some 15 years.
This was related to our own flow sender. It was installed in Jabiru aircraft successfully until they introduced the wing tanks - the first installation went wrong very soon. The sender rotor stopped turning. When we investigated the rotor was frozen in place caused by a waxy substance that settled in the bearings. After cleaning the sender it works fine again but after an hour or so in the aircraft it happened again.
After repeating the process three times it kept on working.
The same happened soon after with other installations that had the new wing tanks.

The fuel was leaching our some whitish colored waxy substance from the inside of the wing - after a while that went away.

We have not encountered the same with other, similarly constructed aircraft.

Your case may be something similar perhaps ?

[sparxfly]

I have struck a similar problem in the past, where a whitish waxy substance blocked up a fine mesh inline fuel filter.
You could blow throught the filter OK while it was dry, but the moment it was wetted with fuel it blocked.
It was apparently Durene- leaching from the inside of 2 new 20l fuel containers I had recently bought.
Wikipedia says it is also a component in MTG (methanol to gasoline) conversion.

[morne75]

Wel long story short, I replaced the sensor..
What I can say is this, if the aircraft is left in storage for a number of months or years it's best to drain the fuel from all the hoses, that included draining the feul sensor unit.

Thanks for the response guys

[Dobbs]

Please can someone help - my MGL fuel flow meter stopped working recently. When I suck through it, the impeller turns, there is 5 volts on the + side of the RDAC, the ground and signal wire connections are good, however, there is no readout on the MGL panel.

Thanks in advance for any assistance.