Pressure Test Failed

I didn't get up as early as I had wanted to and so the early morning priming session had to wait. Just as well, as I had later found out that I hadn't really prepared all the parts correctly yet.
I started in the shop by cleaning and scuffing the parts I had missed and setting up the paint both to accommodate the large canopy frame, allowing me to walk around it when painting.


These are some of the parts that will get painted.

When this was all done the friendly USPS postman came by and dropped off the parts I had waited for from Aircraft Spruce to get the pressure test done. So, I quickly pulled the tarp off of the fuselage and set up the fittings to connect return and supply line at the tank area to pressure test the whole fuel line at once.
Oops, that didn't work out at all. The pressure I put in with a ball pump didn't even hold for a few seconds. And I was wondering if I could really hear a hissing sound or if this is a sign of developing a tinnitus... Well my ears are ok. It turned out the ball pump is so cheap it wouldn't hold pressure slowly leaking air unless you kept on pumping.
I removed the ball pump and hooked up the tire filler gauge to the compressor.
Ah, that was better!
Oh, wait, wasn't this 0.1 psi higher a moment ago?
Sure was!
So there was a leak! At least one, I should say ...

I used the fuel valve to shut off everything behind it but I till lost pressure. That could have meant that either the valve is leaking, or the leak is in front of the valve, or the valve doesn't perfectly shut off.

I first wanted to make sure my test setup was leaky itself, so I removed and tested the pressure gauge and Schrader valve assembly. It turned out to be perfectly sealed.

I didn't trust the valve and started removing flared tube connections one by one. Cleaning them, greasing them with fuel lube and putting them back on. Still a leak.
When I got to the valve I decided to stop and see if I can locate the leak with soapy water as I was starting to believe the valve did indeed cut off the aft line.

After cleaning the whole forward tunnel with soapy water I finally sprayed it on the fitting end of the aft connection of the fuel flow sensor. Aha! That's how a bubble bath in the making looks like. It was leaking not at the flared end but where the fitting screws into the sensor.

I removed the fitting, cleaned the threads as good as I could and put a thick layer of Rectorseal No. 7 on it and screw it back in. While I was doing that I was thinking that this could have all been easily avoided by getting the pressure test equipment before even starting on the fuel lines. That way I could have tested every component before putting it into the plane. Now I'm thinking about pressure testing the brake system before putting fluid in it as well!
I assumed that an immediate follow-up pressure test could jeopardize the seal and so I decided to stop there and let the sealant cure before I add pressure to the system again.

I went back to prep and prime and finished the priming part. I decided that the steel parts as well as the parts that get into contact with the elements should get primed green as that stuff is the better corrosion primer. This would include the flap handle, the flap guide assembly and the canopy and the canopy skirts.


After some two hours the stuff had turned green.


Somewhere in between, I forgot when, I also primed the servo pushrods. Because of that dreaded fuel line leak I didn't get to the installation of the servos today.