Header tank

Australian designed and manufactured Jabiru Aircraft/

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chrisni
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Header tank

Unread post by chrisni » Sat Apr 09, 2016 8:38 pm

Please could someone help me with advice:

I replaced my electric fuel pump today so I had to empty the header tank located on the floor behind the passenger seat (J170) by opening the drain plug under the fuzz. After I installed the new pump and opened the fuel valves I noticed that the header tank did not fill up. Only 3/4 filled with fuel with 1/4 being air.

How do I get the air out?
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Re: Header tank

Unread post by scsirob » Sun Apr 10, 2016 9:40 am

The problem is that the air has nowhere to go. You have to open up a way for the air to get out.
So what I did was this:
1. Close the valve of one wing tank to keep that fuel in.
2. Drain the other wing tank and header tank. This ensures an open air pathway from the header tank through the empty wing tank and wing tank vent.
3. close the drain valve
4. Open the valve of the wing that is still full. The header will fill and air will be pushed up and out through the empty wing tank.

Can't tell if this will work on a Jabby, but it worked for me.
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ZuluBen
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Re: Header tank

Unread post by ZuluBen » Tue Apr 12, 2016 10:54 am

Hi Chris.

The Header tank has a breather line that goes from the top of that tank, via the RH door pillar venting into the RH tank.

Often this line is a bit "restricted"

Try putting the LH (Port) wheel on a block and rocking the wings and watching the bubble?

Else, open up the cover on the door pillar (behind Co pilot seat) and identify the breather line.

Disconnect and suck (carefully :lol: ) till clear.

Inspect, and secure before closing up.

Tell us how it went.
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Re: Header tank

Unread post by T4flyer » Tue Apr 12, 2016 12:54 pm

When I drained my fuel system to calibrate tank levels I also drained the header tank to make sure the warning light came on as the tank emptied. Once I had finished I put fuel into both tanks but nothing flowed into the header tank :shock: tried rocking the plane gently, then a bit less gently 8-[ still nothing flowing to the header tank. I was totally dumbfounded, how can the fuel not flow, it had to...

In desperation I put the fuel cap back on the left tank, climbed up the step ladder to the right tank, took a deep breath, put my mouth over the fuel spout and blew :oops: sounds silly but the fuel started flowing straight away, it filled up the header tank and a couple of hundred hour later she is still going strong. I don't know why this worked or if it will work for someone else, but it might be worth a try.

Warning don't be tempted to pressurise the tank with a compressor or if you have lungs like a Springbok rugby player take care, after all, you just want the fuel to flow, not to blow the fuel tank or the whole wing apart.. :lol: :lol: :lol:

Cheers, Don.
chrisni
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Re: Header tank

Unread post by chrisni » Wed Apr 13, 2016 9:40 pm

Thanks so much for the advice which is much appreciated.

So on Saturday morning I will be emptying one tank, sucking on fuel pipes and rocking my jab! Problem solved. I hope!

Cheers
Chris
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Re: Header tank

Unread post by Pepler » Thu Apr 14, 2016 9:58 am

Very interesting post as we did this exact same thing last Saturday. (J430 - 2009 model) Also drained header tank empty to check low fuel level light. The fuel drains quicker through the drain valve in the bottom of the header/accumulator tank than what it flows in from from the wings.Fuel light comes on and goes out again once you let it settle for a minute or so. We repeated a couple of times to see whats left before it stays on permanent. When it stayed on we drained 5 L remaining in the header tank. In process of "confirming" the 5 L we again filled up with 5 L after complete drain. After adding 1st 5L into RH wing tank you could hear it running into header tank and you can see the top 1/4 "filled with air". Added another 1L and fuel level warning light went out. We then ensured plane was parked level and filled up in 10L increments, marking the dipstick each time. After the process of filling and measuring, header tank had enough time to vent and was also filled to top.
POH says 135L total fuel & 124 Lt usable. 11L "not usable". Low fuel level light comes on when just 5 L left and the pickup is in this tank. Theoretically you are then already on borrowed time. Bottom line, don't run it till the light comes on like my wife does with her car.
We filled 68 L / wing tank (to the brim) and adding the 6 L in the header tank = 142 L total.
Adjust mass and balance calculations accordingly if necessary as you might have extra 5 Kg on board when filled to the brim compared to POH indicating 135 L.

Enjoy the exercise, it makes a world of difference to fuel planning and confidence if the dipstick confirms what the EFIS is telling you.
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Re: Header tank

Unread post by scsirob » Thu Apr 14, 2016 3:30 pm

chrisni wrote:.. I will be emptying one tank, sucking on fuel pipes
Fair warning, be *very* careful with this. If you inhale fuel, you can suffocate. Fuel fumes are heavier than air, just a little bit of fuel in your longues may be lethal.

Rob
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Re: Header tank

Unread post by chrisni » Sun Apr 17, 2016 9:19 pm

it turns out that the problem was easy to solve.

The air bubble accumulated because the breather outlet is slightly lower than the top end of the header tank so the air could not escape. All I had to do was raise the one wheel, as Ben had suggested, and the air vented. Voila!

Easy once you know where the breather pipe is located. Thanks Ben.

I fixed it in time to attend the EAA fly-in in Underburg today. That part of the Drakensburg at this time of the year is simply stunning.

Thanks for all the advice guys.
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ZuluBen
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Re: Header tank

Unread post by ZuluBen » Mon Apr 18, 2016 11:56 am

8)

Lekker man, lekker! :wink: :lol:

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