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So, you think ya got em all?

bret

Well Known Member
I was in the shop today and decided to set fuel pressure at the regulator and test the fuel system for the first time, made up transfer lines and a ground wire for the 5 gallon gas can, (wings off) and discovered port plumbing was reversed at the duplex valve, so I crawl under to switch the lines and discover one of the fuel line was loose! After years of hearing of this and told myself over and over to check every B nut during the build, and I did over and over, I still had a loose fuel line! I guess I am human and will make mistakes, still cant believe this........could have been real bad.......
 
That's why it is so important to have as many experienced sets of eyes look at your Procter as it finishes up. I never dependend on myself or the inspector alone!

Others always find errors I miss.
 
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also check the plug on the top of the gascolator. I found mine leaking after a couple of early flights. It wasn't tightened.
 
Every experienced builder that walks through your hangar should have access to a wrench and a roll of blue tape. Check anything you want and tape anything you don't like. I once left a buddy's engine compartment looking like a blue tape confetti bomb went off in it....you can't have too many eyes on.
 
Nice Catch

I performed the initial flight on an RV a long time ago (not mine) that had the left tank plumbed to OFF, meaning when the pointer was in the LEFT position, the fuel was actually OFF. Only my 30 second full power runup prior to takeoff prevented me from having some unplanned excitement, or worse, as the engine quit on the ground.

Vic
 
It is true that we're all human. We just need to know it. I feel so fortunate to have an "experienced builder" built in. She always knows when I've messed with the airplane and I leave things open so she can check my work when I'm not around.

Other things that we do when working together (often) is each person does different "phases" of the job with a final cross check.
 
It isn't just construction, it is maintenance as well. I completed the FWF portion of my condition inspection yesterday and managed to bungle the timing process on the PMag once, and when I corrected it and buttoned up everything, I realized I had to de-cowl again to reattach the MP line. It was like a Three Stooges episode...

And hot.
 
It is true that we're all human. We just need to know it. I feel so fortunate to have an "experienced builder" built in. She always knows when I've messed with the airplane and I leave things open so she can check my work when I'm not around.
Other things that we do when working together (often) is each person does different "phases" of the job with a final cross check.

Same here! Ann will not allow me to "re-cowl" the airplane even after an oil change until she has inspected and OK'ed.
 
Highly recommend an air leak test before using any fuel.

Having inspections is good, but realize you can test the system for leaks alone and it will tell you if it leaks. I blocked the system at the fuel pump exit, and at one wing root. Then added 30 psi to the other wing. Locked the valve and the gage dropped. I found the leak, repaired, and left it overnight. NO drop overnight.

Both my 10-friend and I found leaks like this. It is easy and will always find a leak.
 
That's a good idea, but I have a slightly more complex fuel system, supply and return both tanks, but that's a good idea! got a steady stream of return fuel @ 35 PSI both tanks.....@ tank supply and return. All high pressure is on firewall side.
 
Just this weekend I positively determined that the B nut on the left fuel tank air vent - on the inside of the tank - was so loose I could tighten it with my fingers.

Don't know if it's been that way or got that way or, if it got that way how it got that way.

But it happens.

Now I have to tighten it and figure out how many turns (or facets) past finger tight I need to go. I have to get it right because I DO NOT want to go through the thrills of removing an access plate again if I can avoid it.

And you can bet I'm going to have other "eyes" (fingers actually) checking it out.

Somehow these things happen and you have to pay attention to every little oddity you run across while flying or maintaining the airplane.
 
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It isn't just construction, it is maintenance as well. I completed the FWF portion of my condition inspection yesterday and managed to bungle the timing process on the PMag once, and when I corrected it and buttoned up everything, I realized I had to de-cowl again to reattach the MP line. It was like a Three Stooges episode....

Thanks, Kyle! Your confession did me good .... I thought I was only one who made those kinds of "omissions". Some days I'm REALLY glad no one is around to observe my re-dos"
 
This isn't fuel system-related, but early on in Phase 1 I was getting sketchy CHT readings on one cylinder. So I unbundled the wires, checked the connections and, sure enough, found the problem. Although I was POSITIVE I had crimped all the connectors, there was one wire just rattling around in an uncrimped barrel, making intermittent contact. At least it was an easy fix....20 seconds with some crimping pliers.

It happens, despite our best efforts.
 
B Nut Loosening

I have encountered loose B nuts on a number of fuel systems and locations on RVs.
I am finishing the build on a second RV-8 that included wings purchased from others. For differing reasons during the builds I removed the access panel to the fuel tanks. While doing a general look around found the B nuts on fuel pick ups only finger tight. This included fixed tubes and flop tubes. On the flop tube every fitting was loose from the attachment at the bulkhead fitting to the brass end. This has me thinking Vans may need to have a more robust reminder to tighten these fittings prior to closing the tank.
I have also encountered an issue on another RV-8 that was a QB kit. The customer had fuel streaming from the vent while parked. The problem was the B nut for the internal vent line was not attached to the bulkhead fitting at the inboard tank rib. If topped off a siphon would start and continue till the fuel level drained below the fitting. This left a very large pool of fuel on the hangar floor. The aircraft had 4-500 hrs so either the nut was not torqued properly or there is some mysterious vibration that is loosening these nuts. My money is on improper torquing.
Prior to a final closing of your fuel tanks or if doing some other repair take time to recheck-rechecking these fittings. Another level might be to consider a dab of ProSeal on the nut after torquing to stake it in place.
 
The aircraft had 4-500 hrs so either the nut was not torqued properly or there is some mysterious vibration that is loosening these nuts. My money is on improper torquing.

And what is the proper torquing?

thanks!
 
One problem if you are tightening a hose is to use three wrenches, one to keep the opposing Tq off the fitting, one to keep the (hose) from turning, and one for the B nut. I Also notice on the aluminum fittings, they loosen up easier compared to the torque you apply when tightening?
 
And what is the proper torquing?

thanks!

Use the Vans table for torque for 3003 al lines. Here is a thread that covers the topic in depth. Read the whole thread for content, the good information is scattered through there. There are experiments and validation.

http://www.vansairforce.com/community/showthread.php?t=123689&highlight=torque

Definitely DO NOT use higher torque than nominal in the table. There is a bid difference between dry and lubed in tube deformation, and it is insanely easy to get lube on that flare. If you use a drop when flaring, and just wipe with a dry towel, it still has lube there.
 
Use the Vans table for torque for 3003 al lines. Here is a thread that covers the topic in depth. Read the whole thread for content, the good information is scattered through there. There are experiments and validation.

http://www.vansairforce.com/community/showthread.php?t=123689&highlight=torque

Definitely DO NOT use higher torque than nominal in the table. There is a bid difference between dry and lubed in tube deformation, and it is insanely easy to get lube on that flare. If you use a drop when flaring, and just wipe with a dry towel, it still has lube there.

That is a great thread. Thank you for supplying the pointer.
 
As a reminder to myself, I did a couple of things during the build.

Maybe this is same as most everyone else. It helped me.

1) I used torque seal to mark fasteners and fluid connectors that were 100% "finished". (Note: I agree with Walt about not relying on that paint as an indicator at annual. Many fasteners had "settled in" and needed a few flats to regain torque values at annual)

2) On the incomplete connections that could more likely kill me, I put flags of various sorts such as red tags wired on or a big flag of blue painters tape.

There were many structural fasteners that could go together permanently early in construction. They were easy of course. However, that final year of construction saw a huge amount of off-on/in-out/cut to fit/paint to match :) activity and I had to be very fastidious about fastener/connector marking.

Added to that, as has been said above, have an inspection party with the local EAA or allow any visitors with a modicum of aviation knowledge to look over your plane frequently as you get towards the end.
 
I went and got my pitot/static check done on Friday, had to chase a small static leak, and found my fitting where the static line goes into my Dynon ADAHRS to be only finger tight. Fixed that, checked the others, and sure enough the pitot and AOA were also just finger tight.
 
That's why it is so important to have as many experienced sets of eyes look at your Procter as it finishes up. I never dependend on myself or the inspector alone!

Others always find errors I miss.

That is a good idea Paul. I have only heard of a few inspection parties on here where others come to try and find something that needs corrected, I wonder if many of us are afraid of the criticism and therefor do not invite others over to look at the project. I have only had one fellow RVer over, Hi Brian, and has given me lots of valuable advice and help. This place also is a great place to post pics and get a response....or a place to grab some popcorn and be entertained while learning ;-)
 
I don't think I was ever lacking eyeballs to critique my work. Heck, the airplane arrived at the airport and a line formed!

"The line starts here boys."
IMG_3725_res.png
 
That is a good idea Paul. I have only heard of a few inspection parties on here where others come to try and find something that needs corrected, I wonder if many of us are afraid of the criticism and therefor do not invite others over to look at the project. I have only had one fellow RVer over, Hi Brian, and has given me lots of valuable advice and help. This place also is a great place to post pics and get a response....or a place to grab some popcorn and be entertained while learning ;-)

The dynamics in a party may not be the best.

Invite them all over one at a time, I bet you'll get a better inspection.

Especially get the guy/builder with good close-up eyesight. :)
 
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