Header Tank

 A lot of this is covered in the 'Fuel System' post, but there are some additional details on the header tank - specifically the systems that measure fuel level in this post.

From a mounting perspective, the header is mounted on the forward tunnel just aft of the firewall.  Tabs have been welded on the top of the tunnel truss with captive fasteners (#10) in 4 places.

I mocked it up in wood to begin with to figure out the overall fit.

The pumps and filter fit under the header.

A friend of mine got the header made.  He had a shop bend the aluminum, and then he welded up the header.

Post tab welding

After finishing (tank was treated with Alumiprep and Anodyne, then primed, then painted).

My big concern with a header was knowing how much fuel is in it, and more importantly when it gets low on fuel.

In my panel design, my original plan was to have a capacitive probe in the tank to know how much fuel is in it.  Unfortunately, Advanced only supports 4 tanks (and I have 5 - 2 mains, 2 aux, and 1 header).  So I needed another solution.

Enter Radiant Instruments.  They have a number of innovative fuel probes.  My issue was I did not have room for a fuel gauge, so I decided to use fuel level senders (that basically say there is fuel at a given level, or not) with their LED indicator.  The indicator says "there is fuel, or there is not fuel".  2 of these mounted on the tank will tell me if I ever get the header too low.

So now the discussion goes to where to place them, which leads to fuel flow, header capacity, and time between warnings.

Current workbook with calculations:

Current sensor locations and indicator mess.

Bottom line(s):

• From my calculations, the fuel system can deliver 63 GPH to the header.
• At full power, the engine should draw about 22 GPH
• If you get the initial low fuel indication on the header (which is right in front of the pilot), you have 1.66 minutes to correct.
• When the 2nd sensor shows low, you have 1.44 minutes to correct.
• The header has fuel for 4 minutes at full engine power (220 HP)

These are all calculations at this point.  Proof will come on the first flight.  But, based on these numbers you should NEVER see a low fuel indication on the header... ever.  Famous last words...

Panel header fuel level indication above the pilot side display.  Very simple.  Green = good, Red (flashing) = Bad.

Header tank in place with lock on the shutoff valve.  Also doubles as a mount for vertical fuel line.

So after a lot of messing around (and many months), it is finally in its (hopefully) finished configuration.  All fasteners are installed.  The only thing left to do is wire the fuel pumps, which I may do today assuming I have all the stuff.

Now it is onto the vent lines...