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NowackLinden(at)gmx.de
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 Posted: Sun Apr 22, 2012 2:24 am Post subject: Tank Sensor Trouble |
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It`s been a while since you heard from me and my D-ELIY (Kit no. 89),
which is the first Lightning in Germany. In the meantime I have finished
the building phase and have started the certification phase. Some time
soon I plan to write an article about this for the newsletter, so I
won`t go into details here.
Yesterday my Examiner came to Luetzellinden airfield (EDFL) , and
examined my Lightning for the technical acceptance certificate that I
need to get a Provisional Permit To Fly from the German LBA, our FAA.
It took 7 hrs, he looked really into everything and , of course, found a
lot of (minor) things had made not quite correct to his judgement. But
all in all he was satisfied with my work and the tech state of my airplane.
One important part of the examination is the fuel tank sensor and
indicator calibration. And there the trouble started: we could`t for
the heck of it get those Princeton capacitor probes to work properly.
They woudn`t give useful data outputs with less than half full tanks.
They both just showed zero fuel all the way from half full to empty. I
had the probes calibrated empty and full before as per instruction,
which didn`t work at first with the left probe. Took three trials until
I got the LEDs flashing correctly.
Yesterday we sloshed fuel around and filled and emptied the tanks for
three hrs. No luck!
The problem is either the alcohol that we have in our auto fuel(5%) or
its a compatibility problem with my MGL Voyager EFIS or something else
entirely. Who knows? Anyway , I don`t.
So now I`m quite desperate! And I am just aboutfed up with those &%&$
probes!
Right now I see no way out other than to bite the bullet and install
some good oldfashioned VDO resistive float sensors.
I think I can get away without having to remove the wings by installing
those probes from the top of the wings right at the root, where I have
glued some coarse plastic film to step on anyway. So the esthetic damage
would be minimal.
I will just need to ask Nick if he sees any stability problems from a 2"
hole in the wing top, which I don`t expect.
Nick, if you read this you can just give me an answer, so I don`t have
to call you on monday.
So if some of you have info to share about those Princeton probes or
have experience with other sensors , please tell me!
The attached picture is from the happy day in January when I had the
wings bolted on to my Lightning in my EDFL hangar space. In case you
wonder why it looks a bit different than your Lighnings: It has an
ULPower 350i engine and a 3blade CS prop by Woodcomp.
Gerd
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selwyn
Joined: 12 Mar 2008
Posts: 102
Location: Australia
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| Posted: Fri Jul 20, 2012 2:05 am Post subject: Re: Tank Sensor Trouble |
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Hi, You are not alone with this. For a long sometimes contradictory discussion see this http://www.mglavionicsusers.org/forum/viewtopic.php?t=1028
The problem is most likely not with the probes but with the Voyager RDAC not being able to handle the high impedance voltage signal from the Princeton probes. My understanding is that you need to remove the pull up resistors from the RDAC circuit board but I have not done this to mine yet. Others have and had good results.
I believe the latest RDAC has external switches to achieve the same thing.
As a rough check on your probes you can measure the voltage output with a multimeter whilst filling the tanks, you should get a steadily increasing voltage allowing for tank geometry.
I realise this is a late reply but I hope it is some use.
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_________________
Cheers, Selwyn
Kit 66 VH-ELZ |
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nowacklinden(at)gmx.de
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| Posted: Sat Jul 21, 2012 3:33 am Post subject: Tank Sensor Trouble |
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Selwyn,
I really had enough of the trouble with the capacitance sensors. On top of the compatibility troubles with the MGL EFIS I found out that they donĀ“t work well at all if you have an alcohol percentage in the fuel- European 95oct auto fuel contains 5% alc!
So I went and drilled 3" holes into the top of my my wings and concentric 1 3/4"/44mm holes into the top of the tanks, right at the wing root. I bought two marine type VDO (as recommended by MGL )float type sensors , modified them a little and epoxied them in. Calibration was no problem at all. Now everything works just fine!
If anyone needs info about this, or pics, just ask!
Of course you could build those sensors into the wing roots in the same place where those Princeton things would go. If you have your wings not yet in place. Which i didn`t.
Gerd Kit no.89, D-ELIY
-------- Original-Nachricht --------
| Quote: | Datum: Fri, 20 Jul 2012 03:05:32 -0700
Von: "selwyn" <selwyn(at)ellisworks.com.au>
An: lightning-list(at)matronics.com
Betreff: Re: Tank Sensor Trouble
|
| Quote: |
Hi, You are not alone with this. For a long sometimes contradictory
discussion see this http://www.mglavionicsusers.org/forum/viewtopic.php?t=1028
The problem is most likely not with the probes but with the Voyager RDAC
not being able to handle the high impedance voltage signal from the
Princeton probes. My understanding is that you need to remove the pull up
resistors from the RDAC circuit board but I have not done this to mine yet. Others
have and had good results.
I believe the latest RDAC has external switches to achieve the same thing.
As a rough check on your probes you can measure the voltage output with a
multimeter whilst filling the tanks, you should get a steadily increasing
voltage allowing for tank geometry.
I realise this is a late reply but I hope it is some use.
--------
Cheers, Selwyn
Kit 66 VH-ELZ
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=378787#378787
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n45bm(at)yahoo.com
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| Posted: Sat Jul 21, 2012 6:50 am Post subject: Tank Sensor Trouble |
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Hello Gerd,
Yes, I would like to see some pics and get any other technical info on how yoiu did this. I'm about to drill the holes for the capacitance sensors, but I would like to see what other options are available, especially as I'm about to purchase my EFIS, maybe from MGL. I'm going to Oshkosh next week to compare and buy my avionics. Thanks for your help.
Regards,
Bernardo
--- On Sat, 7/21/12, Gerd Nowack <nowacklinden(at)gmx.de> wrote:
From: Gerd Nowack <nowacklinden(at)gmx.de>
Subject: Re: Re: Tank Sensor Trouble
To: lightning-list(at)matronics.com
Date: Saturday, July 21, 2012, 6:33 AM
Selwyn,
I really had enough of the trouble with the capacitance sensors. On top of the compatibility troubles with the MGL EFIS I found out that they don“t work well at all if you have an alcohol percentage in the fuel- European 95oct auto fuel contains 5% alc!
So I went and drilled 3" holes into the top of my my wings and concentric 1 3/4"/44mm holes into the top of the tanks, right at the wing root. I bought two marine type VDO (as recommended by MGL )float type sensors , modified them a little and epoxied them in. Calibration was no problem at all. Now everything works just fine!
If anyone needs info about this, or pics, just ask!
Of course you could build those sensors into the wing roots in the same place where those Princeton things would go. If you have your wings not yet in place. Which i didn`t.
Gerd Kit no.89, D-ELIY
-------- Original-Nachricht --------
| Quote: | Datum: Fri, 20 Jul 2012 03:05:32 -0700
Von: "selwyn" <selwyn(at)ellisworks.com.au>
An: lightning-list(at)matronics.com
Betreff: Re: Tank Sensor Trouble
|
[quote]
Hi, You are not alone with this. For a long sometimes contradictory
discussion see this http://www.mglavionicsusers.org/forum/viewtopic.php?t=1028
The problem is most likely not with the probes but with the Voyager RDAC
not being able to handle the high impedance voltage signal from the
Princeton probes. My understanding is that you need to remove the pull up
resistors from the RDAC circuit board but I have not done this to mine yet. Others
have and had good results.
I believe the latest RDAC has external switches to achieve the same thing
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