Monday 28 April 2014

Week 143 - Fuel system cont.

Hours to date 1259.0

I had a good weekend of progress with the fuel system.

The fuel pump mounting released okay - I then cut down the threads of the composite screws so they're a bit neater.

I still need to go back and add some more flock in the holes and maybe put a layer of glass over that lot.

In the meantime I got on with fitting hoses.

All the fuel system up to the firewall (bar the high pressure feed line) is done. I'm going to use steel braided hose for the high pressure part and also for the small piece of hose that goes on the outside of the fuse before the feed line goes into the tank (as it's stiffer and less prone to wear).

As you can see from the photo below I've got a rather complicated solution to the flop tube arrangement. I have to do this as I want the maximum amount of hose length for the flop tube and cannot go right up the front of the leading edge part of the tank with a straight fitting because the front wing pin bearing will go their.

So we have to go back to go forwards - as it were.

I'm happy to report that after testing on the bench it should work fine - plenty of movement in the hose at that length - I only ended up taking 25mm from the full length of the Vans supplied hose.

The other good thing about this arrangement is it puts the flop tube further into the tank - away from the drain and overflow valves and also the capacitance probe for the fuel gauges - no bad thing.

I went ahead and drilled out the hole for the feed line into the tank. I can see why Pete doesn't think it necessary to reinforce this area - the tank is very thick at the root end. I will use epoxy (probably a runny flock) to secure these fittings when I do it finally. Pete says he uses 5 min epoxy - I've had mixed results with 5 min epoxy so prefer to use the 'good stuff' for this.

I'm also pleased to say that the other hoses all seem to fit well and have plenty of movement on the inside of the fuse. The movement is to allow for the quick disconnects to be drawn outside of the fuse when the wings are taken off (or put on).

I've got a couple of parts coming from Mark at Galaxy Microlights to finish off the Fine Filter section. And I've ordered a fuel pressure sender (Dynon type) to go on top of the Banjo bolt that exits the Fine Filter.

My plan is to get all the fuel (and oil cooler) hoses done all the way up to the firewall, this is to get as much work done related to the engine before actually ordering it. (it's bad for the engine to sit for any length of time without running as corrosion can set in internally).

I've also got to fit the fuel overflow hose and valve plus the drain valve to the fuel tanks.

The only thing I won't be able to do at the moment is fit the return line bulkhead fitting into the tank - I want to do that when I put the wings on to get it in exactly the right place.

I'll post a link to a very helpful video in another post - it's all about how to fit hoses. I found it very helpful and used all their techniques bar one - I used masking tape on the hose rather than a marker pen to make sure it did not move when fitting - the marker would not show up on black hose anyway.

The must haves are: a Dremel with a cut off wheel, Aluminium jaws (for holding the fittings without damaging them) and ali spanners (again so you don't damage your fittings - they are soft anodised ali and mark easy).

Will hopefully have one tank done by next week. After that I will add some composite screws (with P clips) for retaining the hoses.

Flop tube arrangement - piece of hose between the two red fittings at the bottom still to come.

Fuel pumps mount - after releasing - some more work to be done here.

Time to fit some hoses!

Composite Screws shortened

Ali jaws for your vice - must have for hose fittings

Ali spanners and Dremel with cut off wheel - also essential tools

Masking tape on hose to monitor movement when fitting

Port side view of hoses in place

Starboard view

Outboard view

Feed line fitting in tank

Flop tube fittings inside view of tank

Flop tube shortened and fitted

With flop tube in place - works okay

Inside view with hose in place
 


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