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Fuel Level
#1
I've spent a fair bit of time now on different options for detecting fuel level on my heli and I thought I'd pass on what I've learned.

Initially I tried a capacitive fuel probe (Centroid products).
The problem is that fuel with ethanol has more capacitance than fuel without.
I end up using both, so if I calibrate with fuel that has ethanol, the reading will be incorrect when I use fuel without.

The probe has a full detect that re-calibrates when it detects "full", but I rarely fill the tank, especially since it's an XEL so of course I wouldn't think of carrying more than 5 gallons.

I ended up using a regular old float sender, a Sunpro CP7583 that I bought through Amazon.
It took a bit of bending and modification but it sits nicely now and swings freely in the tank.
It works well with the Enigma panel.

I want to have a fool proof backup as well.

I experimented with a small float with a magnet inside in the site tube and a reed switch on the outside.
I ran into two issues, first the float would get stuck in the site tube, second the magnet's orientation would change and it wouldn't close the reed switch.
I finally gave up on this.
I looked at capacitive proximity switches against the site tube but I couldn't find one small enough, and they were kind of pricey.

I'm currently working with a Honeywell liquid level sensor that will be "Tee'd" in at the bottom of the site tube.
I have the LLE101000 sensor and I've done some testing with it, looks like it will do the job.
http://content.honeywell.com/sensing/...

The plan is to wire this into a separate digital input on the Enigma I/O extender so I can get an audio and visual warning from the Enigma if the detector does not see fuel.

I still need to pick up a couple of fitting to plumb it into the site tube, I'll post more when it's complete.
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#2
I ordered for my Mosquito XE, MGL Flight-2 with capacitive fuel level sensor and flow meter. I hope there are no problems.
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#3
Or you could do it the old fashioned way... Sight Glass to get your fuel level at the beginning of the flight and a stopwatch so you know how long you been running! That is the way I do it with anything I fly. I have had a fuel gauge on a H300 tell me I had 10gal more than I did, and on an H500C it never moved below half a tank... Work out your fuel capacity, work out your burn rate, and check your clock! Wink
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#4
Ron is right, no matter what system you have, know how much fuel you have on board, your fuel burn and your time running, this is the only sure way. When u land try and guess what u have on board and stick the tanks for verification. I have picked brand new mulit million dollar aircraft from the factory with inop or inaccurate fuel gauges, this is a common problem. Technology is great but u can never get away from the basics.
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#5
I'm certainly not suggesting that a fuel gauge and low fuel sensor are a substitute for the common sense of keeping track of flight time and being aware of fuel and flight time remaining.
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#6
The FAA has an Advisory Circular called TIME IN YOUR TANKS. It talks about pilots developing the mentality that fuel should be based on quantities in UNITS OF TIME and NOT in gallons or litres, etc.

It also addresses the principle of accuracy of fuel gauges and how to never trust them.

If you ask me, I was glad that the fuel gauge in my Brantly was so inaccurate, that I never even looked at it.

On a Mosquito, if there's a straight shot into the filler neck, a piece of 1/4" dia aluminum tubing, calibrated with marks every 10 MINUTES would be a great way to know how much TIME is in your tank before EVERY takeoff. Just keep it stuck inside THE COCKPIT somewhere with velcro.

Make sure to wear a watch and note talkeoff time on every flight.

Bryan
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#7
Lorne,

Hey I wasn't knocking your findings, keep them coming, just adding some experience to the conversation, I think what your doing is great, when I get my ship up and running you will be one of the first I will ask questions in regards to the Enigma, LOL!
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#8
Hey Rob,

It's alright, not worries.
I really wasn't trying to stir things up, just wanted to share some ideas and what I've learned.
The projects are very rewarding on their own, and I'm happy with the added flight awareness and safety they add for me.

I must admit I'm getting a little gun shy about posting about the projects.
Oh well, a learning experience.
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#9
Lorne,
Hey I know what u mean about gun shy about posting and it shouldn't be that way, too many shooting people down on here, I. Wasn't shooting u down at all, I should have expained that in my original post better, kinda the same reason I hate texting, anyway. The reason i agreeed with Ron's post was I have personally seen too many fuel related accidents, not read about them, seen them. You know this but many reading do not, and when u have an aircraft that by nature that has a lot of inexperienced pilots it always good bring up a good basic fuel reminder. Fuel starvation is as u know one of the biggest accidents still in general aviation and yet so preventable. I personally love reading all your post, your knowledge in electronics is a huge asset to this community and I appreciate it. U bring a yet different and much needed experience to the builders and operators in this community, I thinks its great. Man I'm just a dumb pilot, all I've done my entire adult life and so I'm not qualifed to do much of anything else, why do u think I'm turning wrenches at the factory, I need all the help I can get, lol!
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#10
Hey Lorne, I love reading your posts too!!! I wasn't trying to shoot anybody down, Just as RSM
says, just a little reminder to the less experienced pilots... Anyway, it is guys like you, and the
rest of the mosquito development community that has made it possible for so many people to
realise their dream of owning and flying what I consider to be (in Kiwi speak) a bloody good little
helicopter!

I just remember how I felt as I was refuelling during a cross country flight with my little girl... watching the litres
going in (or rather gallons... our fuel pumps are in litres but of course the H300 is in gallons!) thinking man I am
glad I didn't just glance at the fuel gauge and think I had enough to get back to the home airfield. I glanced at the fuel
gauge in flight, thought hmmm... looked at my watch and thought aha! Land and get fuel!

Hopefully there is a couple of pics here... the fuel at take off (32.6 U.S. Gal) My little girl Laila at North Shore Airfield (NZNE) getting fuel! and some of the water we cross on a typical cross country from Ardmore (NZAR) in South Auckland heading north to Kawau Island where my lady Debbie and I work.


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