[istrumit]

I did not build my ten. From another post, I recently found a fuel leak at the coupling pictured here. The nut and the entire coupling were covered in blue residue as was the floor directly beneath.

I tightened the coupling and I have not had a leak in the 5-10 hours of flight since then.

My question:

Is this a standard fuel plumbing arrangement ?

I don't understand what this leg of the line does. It appears to just dead end into the brass block shown.

If someone can please point me to a matching diagram of this area, I would appreciate it.

Scott

 

[DaleB]

Check page 4 of this document... that's a relief valve.

 

[rvbuilder2002]

Of additional concern to me would be what looks like an unrestrained heavy gauge battery cable possibly in contact with the fuel pump

 

[istrumit]

Check page 4 of this document... that's a relief valve.

So, when active, the relief flow would be back 'toward' me in the picture ?

Is that correct ? And where does it flow back to ?

The pump inlet down stream of the selector valve I assume ?

 

[BillL]

Of additional concern to me would be what looks like an unrestrained heavy gauge battery cable possibly in contact with the fuel pump

+1 possibility of 400+ amps direct to a grounded aluminum fuel line -

So, when active, the relief flow would be back 'toward' me in the picture ?

Is that correct ? And where does it flow back to ?

The pump inlet down stream of the selector valve I assume ?

Yes, back through the filter to the pump inlet.

 

[ExtraKatana]

http://airflowperformance.com/wp-content/uploads/2015/12/Auxiliary-Pump-2090255.pdf

Looks like it just needs to be tightened.

 

[istrumit]

http://airflowperformance.com/wp-content/uploads/2015/12/Auxiliary-Pump-2090255.pdf

Looks like it just needs to be tightened.

Yup. I tightened it, although getting a wrench in there with enough room to rotate the box end head was impossible and I had to use needle nose vice grips. That is probably why it was loose in the first place. It was very difficult to get a grip on it.

No issues since tightening.

I'll take a look at that cable. I don't recall thinking that it was a battery cable, but maybe it is, and regardless, its easy to get to so I might as well check it out.

 

[istrumit]

http://airflowperformance.com/wp-content/uploads/2015/12/Auxiliary-Pump-2090255.pdf

Looks like it just needs to be tightened.

While I'm thinking of it, the only reason that the loose fitting in question would leak is that the relief valve is relieving...which makes me wonder how that could be if the engine driven pump is doing its job ?

Meaning, if the mechanical pump is pumping, and the aux pump and mechanical pump are relatively capable of the same flow rate, then the pressure on the outlet of the aux pump should be very low and the relief valve should never activate.

Am I thinking correctly ? Because, it does seem to me like my engine driven pump is a bit flaky and I have been thinking of replacing it.

 

[Veetail88]

I would think that relief valve would be flowing almost always when the electric pump is running as the pump flows much more than the engine uses and it's recirculating and regulating pressure at the same time. Unless of course the pump churns at just the right pressure, which I doubt. While I'm no expert on fuel pumps, in general when a pump is running you need flow through it or it will heat up.

 

[lr172]

So, when active, the relief flow would be back 'toward' me in the picture ?

Is that correct ? And where does it flow back to ?

The pump inlet down stream of the selector valve I assume ?

The high pressure fuel is exiting the pump UP in your picture, filling that gold block with high pressure fuel. The blue cylinder is a 25 PSI relief vavle (regulating the pressure in the gold block and downstream), with the low pressure, relief fuel going DOWN in your picture and coming back up and forming a Tee with the inlet flow just before the large gold cylinder which is a one way check valve (restricting from the Gold block and flowing to the gold block. This is what allows your mech pump to pull fuel from your tanks without restriction.

Larry

 

[lr172]

While I'm thinking of it, the only reason that the loose fitting in question would leak is that the relief valve is relieving...which makes me wonder how that could be if the engine driven pump is doing its job ?

Meaning, if the mechanical pump is pumping, and the aux pump and mechanical pump are relatively capable of the same flow rate, then the pressure on the outlet of the aux pump should be very low and the relief valve should never activate.

Am I thinking correctly ? Because, it does seem to me like my engine driven pump is a bit flaky and I have been thinking of replacing it.

The electric pump delivers way more flow than your engine uses and this excess flow produces the high pressure (apprx. 100PSI +). The relief constantly bleeds off that excess flow to keep the pressure at 25. You will constantly be pushing fuel through that relief whenever the boost pump is running. There would be no fuel flowing past the relief valve and into that tube when the boost pump is off, though it will get a contstant supply of fuel to keep it full, as the mechanical pump is drawing from the same system.

Larry

 

[togaflyer]

Scott, buy the book AC 43.13 1B/2B. (Acceptable methods, techniques, and practices of aircraft inspection and repair). It is also online via the FAA for free, but I like to have the book in hand. This is like a builder bible and covers the FAA approved methods for almost everything on your plane. Read the electrical and fuel sections to start with since your already addressing some comcerns in those areas. Go through the book, then your airplane, and make corrections you identify that needs to be addressed. Any plane you buy, experimental or certified, used or new, will have repair squawks that will need to be address. Figure your first year of ownership will be spent truly making it your family plane. You have a great plane and all your gonna be doing is making far greater.

 

[gasman]

It looks like if the battery cable was relocated, a standard open end wrench could then be used on that fitting.

 

[istrumit]

It looks like if the battery cable was relocated, a standard open end wrench could then be used on that fitting.

It was the bypass line fitting that is in the way. You can get a wrench on the the relief valve fitting, but you can't turn it because of the bypass fitting.

A box end wrench with narrow sides would work, but I could not find one in short order, so I had to use needle nose vice grips.

 

[ExtraKatana]

You need to mark a straight line through all of those fittings with at least some type of marker. You need to be able to visually inspect to make sure none of those AN fittings have backed off. If it has been vibrating around and possibly marring the flare, you might put some soft fitting seals(spruce) between the flare and the fitting. if you see any leaks whatsoever.

 

[istrumit]

You need to mark a straight line through all of those fittings with at least some type of marker. You need to be able to visually inspect to make sure none of those AN fittings have backed off. If it has been vibrating around and possibly marring the flare, you might put some soft fitting seals(spruce) between the flare and the fitting. if you see any leaks whatsoever.

Thats a great idea...the marking, I will do that...thank you.

 

[aturner]

You can cut your wrench in half, and grind down the sides, if necessary, to get into tight spaces. I think I've accumulated an entire set of half-wrenches.

 

[lr172]

It was the bypass line fitting that is in the way. You can get a wrench on the the relief valve fitting, but you can't turn it because of the bypass fitting.

A box end wrench with narrow sides would work, but I could not find one in short order, so I had to use needle nose vice grips.

Research "crows foot" wrench

 

[RV7A Flyer]

I did not build my ten. From another post, I recently found a fuel leak at the coupling pictured here. The nut and the entire coupling were covered in blue residue as was the floor directly beneath.

I tightened the coupling and I have not had a leak in the 5-10 hours of flight since then.

My question:

Is this a standard fuel plumbing arrangement ?

I don't understand what this leg of the line does. It appears to just dead end into the brass block shown.

If someone can please point me to a matching diagram of this area, I would appreciate it.

Scott

Just an observation...the line in question appears to have a nick in the bend which should be addressed...