Header Tank and Fuel System work

 After modifying the header tank, I decided to paint it to make it look nicer.  I taped off the inlets/outlets, thoroughly cleaned the aluminum, and then primed it with an epoxy primer.  After that, I sprayed a few coats of gloss black and it looked great.

Header tank painted

Unfortunately, after installing it temporarily in the fuselage and mocking up some of the fittings, I found an interference issue with some of the inlet hoses.  The tank was mounted a little high and needed to drop down about an inch.  The mounting brackets are welded on which made it more of a challenge, but this was fixed by cutting/grinding a slot in the mounting bracket and hanging it under the V-shaped bracket in the fuselage.  This dropped the tank about an inch, and the bottom mounting bracket still lined up nicely.  Still need to widen one side of the slot a tiny bit more to ensure better clearance from the vertical tube, but that is straightforward.  And of course, in the process of doing this, I scratched the new paint job pretty good in a few spots, so I'll have to do some touch up painting later.

Top bracket modified and tank fitted

Header tank temporarily installed for fitting

Quite a bit of time was also spent planning the fuel line routing aft of the firewall. We are planning on using aluminum line for long runs from the header tank to the fuel pumps, and for the return fuel line back to he header tank.  Connections between the aluminum hard line and other fittings will be done with flexible hose so that vibrations during flight will not affect the system.  We will use larger 1/2"  with 8AN fittings from the wing tanks to the header tank as was recommended by Rotax for the fuel injected 912is, and 3/8" line with 6AN fittings will be used from the header tank to the fuel pumps and for the return line. 

Instead of standard rubber hoses for the various connections, we opted to use some hoses from Jegs (Pro-Flo Extreme) that are lighter and more suitable to fuels that contain ethanol.  The hoses cost a bit more, but still much cheaper than the other alternative of Teflon lined hoses.

In the process of planning, we found an issue with our planned routing between the fuel pumps and the gascolator which made it hard to meet minimum bend requirements for interconnecting hoses. Several options were considered to fix this, and the simplest was to move the fuel pump further from the gascolator which will be detailed in another post.  Hours: 19