Low Fuel Sensor

[henrysamson]

If I understand correctly, you can add a low fuel sensor directly to the aluminum header from Kitfox? However, I see on this thread that the low fuel sensor goes in a small cylinder tank above the header tank? The aluminum tank I have from Kitfox, has a 1/4" pipe connection on the side. The low fuel sensor that I have, is 1/2". Did something change on the header tanks? Or is there an adapter to convert to 1/2"?

I have the older plastic header tank in my model IV. The low fuel sensor does fit in a port in the top of the tank. I have one installed. I have had trouble with some leaking around the various fittings of this tank. A few years ago, I removed the tank, removed all of the fittings, cleaned the threads and reinstalled everything with a two part polyurethane sealant. One version of this is trade named "Proseal". No leaks since.

At the time I was told that the aluminum header tank solved the problem with sealing around fittings but that I would lose the ability to have the low fuel light so I went the proseal route.

[Jerrytex]

I am going to try and adapt from 1/4" to 1/2" out of the side of the header tank, so that my 1/2" low fuel send will thread it. I'll see if I can make it work.

[Maverick]

I have the aluminum tank and my low fuel sensor was 1/2" so it did not fit. Murle drilled out the 1/4" hole out to a larger hole and then arced a 1/4" plate over the old hole. I then drilled through the plate and tapped it to take the 1/2" fitting of the low fuel sensor. We had to deal with a few pin holes in the weld but we finally got it done. It works well but, I do not recommend this route. If you can find a quarter inch sensor that will work through the 1/4" hole, I would go that route. It would seem that the factory would make the hole size for the sensor optional for the purchaser, either 1/4" or 1/2". JMHO.

Maverick

[Jerrytex]

On my header tank, the welded on collar is slightly larger than 1". My plan is to drill the 1/4" hole to 1/2" and tap it. That will leave plenty of "meat" on the collar. Seems like the easiest most reasonable thing to do, to retrofit it.

Edit: The low fuel sensor, the optical one that came with the kit, is actually 3/8" NPT not 1/2" as originally thought, so I'll being drilling and tapping to 3/8".

IMG_3272.jpg

[PapuaPilot]

Food for thought. Why do you feel you a need for a low fuel sensor?

I bought my Kitfox second hand and it came with an optical sensor (ooooh, shinny!) and it fit in the original plastic header tank. When I got the replacement aluminum header tank I went though these same thoughts. At first I convinced myself that I had to use this thneed (Dr. Seuss) in my new header tank, but the new header tank didn't have the fitting (whimper). I finally concluded that I would be a fool if I ever used up the 26 gallons in the wings or ever let myself get below 3 gallons/30 minutes. With my bigger engine my KF can go 4 hours and still have VFR reserves (my bladder won't go 4 hours any more).

Opinion here. Do you know of any other small airplanes like this with a low fuel sensor? The Kitfox has sight tubes on the wings that are very accurate if you calibrate them properly. I also installed a fuel flow sensor with the G3X that is spot on. I really didn't feel the need to add a light to tell me I'm a member of the ID10T club.

The only plane I have flown with low fuel sensors is the Cessna Caravan. This is a lot bigger plane than a Kitfox, and Part 23 certified. The FAA probably required them too. They light up the annunciator panel when a main tank has about 30 minutes remaining per side. But wait . . . I already knew that from the tank gauges, fuel flow totalizer and preflight planning. Honestly they are pretty annoying because they ding at you every time the fuel gets sloshed on & off the sensor. The Caravan also has a fuel sensor in the header tank. I like that one, it means your engine is going to quit in less than 3 minutes. But again, why would you ever unknowingly get in that situation.

No judgement here, just food for thought.

[jiott]

I agree with you Phil, I have the low fuel sensor and there is only one thing it has ever done that I think was useful: On a flight years ago I was heading into an airport to refuel, so my fuel quantity was quite low but not below the proper safety reserves. I had been flying high so I was in a long protracted descent at a fairly steep nose down attitude to lose altitude quickly. Sine the fuel was low my nose down attitude unported the wing fuel tank outlets and I was only running on fuel in the header tank, which quickly reduced the level and the low fuel warning light came on. I immediately leveled out my flight attitude and the fuel system started working properly again; a few minutes later I resumed my descent and landed with no problems. Without the low fuel sensor I probably would have starved and killed my engine before I realized what was going on and leveled the airplane. Most likely I could have leveled and done a restart with no problems, but who knows if it had happened near the ground. This was the one and only time I did appreciate the low fuel sensor. Just some food for thought from an actual experience.

[Jerrytex]

You definately make good points Phil and I agree.

Sad part is 56 percent of plane crashes are fuel starvation and 35%, fuel mismanagement. (https://flightsafety.org/fuel-management/)

We just had a triple fatality 3 weeks ago at my airport due to what is going to turn out to be fuel mismanagment.

My model 4 had one and I always liked the warm and fuzzies of having one. Probably just a mental thing since I like to think I plan for fuel management, but whatever helps quell the voices is always a good thing. Ha. I figured since I have the sensor, drill bit, and tap already, I might as well put it in. It won't cost any money, weight and not much time.

Thanks.

[PapuaPilot]

That is a sad reality.

FYI I use my fuel totalizer to verify the sight tubes. Where I work we teach our pilots to look at the back of the wing during our initial climb for streaming fuel from loose/missing fuel caps.

[Maverick]

In my first Kitfox 5TD, I never recognized the problem of fuel flowing forward in the tanks in a steeper descent. Dumb, I know! It was inadequate testing for sure on my part.

DesertFox4 and I flew to Apple Valley together once when I wish I'd had the low fuel sensor. I calculated that I had enough fuel to make it there from Phoenix and I actually did, although only by a very slight amount. That's when I was entering the traffic pattern having come down to altitude when at midfield the engine died. I looked up and saw fuel but it didn't register with me that it wasn't enough to feed the fuel port at the back of the tank. I declared my situation and did a dead-stick landing. As soon as I stopped, I tried the engine and it fired up and I taxied to the fuel station and filled up. I realize that my lack of diligence in getting to know my plane's quirks and cutting it too close on my reserve are pilot errors (as DesertFox4 doesn't let me forget, bless his heart) but, had I had the fuel sensor tell me I was running on fumes, I likely would have figured out the problem of the nose down attitude letting fuel move forward too much and could have raised the nose, slowed the descent and kept me from needing a clean pair of underwear. Certainly, after having this experience, my fuel management will be more conservative; partly because, like PapuaPilot, my bladder is not as young as it was 16 years ago but, certainly because experience is a good teacher, assuming you survive. . .

[109JB]

All I will say is this. For the past 21 years my job has been to investigate aircraft accidents. My project airplane is getting a new header tank fitted with a low fuel sensor.