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03-12-2015, 09:03 PM
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Join Date: Dec 2009
Location: Montreal
Posts: 1,456
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Quote:
Originally Posted by BillL
Good work getting to the root cause! Stuff happens, on the plus side, your due diligence found a solution quickly.
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And the rest of us learned something for which I sincerely thank you.
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Scott Black
Old school simple VFR RV 4, O-320, wood prop, MGL iEfis Lite
VAF dues 2020
Instagram @sblack2154
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03-12-2015, 09:22 PM
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Join Date: Nov 2008
Location: Scio,Oregon
Posts: 261
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I'm at the point of making fuel lines. Out of curiosity I just made some test flairs with my Parker flaring tool then tightened them to a mating 3/8 fitting. When tightening the nut I could feel when the nut becomes firm against the flair and just a little more tightness felt fine. Then I started progressively tightening more and more checking the flair and tightening again. I noticed that once over tightened then the torque goes down and feels like it's not tight enough but it is stretching the flair and thinning it. Feels like stripped bolt sort of. Disassembling the fitting revealed a flair that looked exactly like yours. What I learned is that over tightening is really easy to do. 1/4 inch tubing is way easier to over tighten.
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Steve S.
Rebuilding RV6A
Scio, OR
EAA Ch. 292
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03-13-2015, 05:19 AM
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Join Date: Apr 2006
Location: Ottawa , Canada
Posts: 224
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A pointer to a past thread
Hi,
I was a totally clueless on how to determine the correct flare on my fuel lines, and a fellow VAF member posted this reply to my query:
http://www.vansairforce.com/communit...88&postcount=6
It turns out there is a standard for everything! I could at least measure my results to see if they were in tolerance. Probably close to the pic inserted earlier.
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Chris Hepburn
Ottawa, ON
RV-8 C-GOGO FLYING
Renew 12/20
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03-13-2015, 05:20 AM
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Join Date: Apr 2010
Location: Ridgeland, SC
Posts: 2,589
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Again--my .02 worth. YES, I do agree with Scott that there are many RV's flying with 3003. Yes, it is relatively inexpensive, and for the job it does, it does it well. Yes, like everything else, to get the best performance from it, it needs to be fabricated properly. I'm not flaming Andy, far from it.
Yes there are some 'minor' differences in fabricating the different tubing. For me, I had to learn to adjust the amount of tube that extends out of the flare bar to get the proper end result. Yes---slightly different (not by much) for 3003, 5052-O, 6061T6, and 304 stainless. I DO use a RFT37 that I really like. HOWEVER---I did have to learn the little tricks to make good flares on the different tubes I was fabricating.
Not everyone one on VAF is going to agree or disagree with 3003 tubing, Like plastic tube for brakes versus teflon hose. We all have our opinions. NO --we arent building space shuttles---well sort of--but we are traveling in these wonderful machines. WE all have had little issues with things about these planes. BUT---we can all take our experiences and knowledge and help a fellow RV brother to solve an problem that could have been catastrophic.
ANDY---good catch on finding the issue---we will all help you to fix the problems.
Tom
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Tom Swearengen, TS Flightlines LLC, AS Flightlines
Joint Venture with Aircraft Specialty
Teflon Hose Assemblies for Experimentals
Proud Vendor for RV1, Donator to VAF
RV7 Tail Kit Completed, Fuse started-Pay as I go Plan
Ridgeland, SC
www.tsflightlines.com, www.asflightlines.com
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03-13-2015, 07:33 AM
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Join Date: Jul 2009
Location: Mojave
Posts: 4,652
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Quote:
Originally Posted by rvbuilder2002
...Nothing wrong with people wanting to use something different ( and others making a business out of fulfilling that desire), but I get tired of the suttle implications that others who do not choose to do the same, are fools.
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3003, while perfectly adequate for this application if properly fabricated, requires a skillset that is largely absent from the average homebuilder. Both my Rocket and RV-8 were done with 3003 and were both "unairworthy" due to poorly executed flares. Add that to the long and growing list of examples on this forum that show the same thing, and eventually one must come to the conclusion that a more forgiving material should be employed. This is no way a slam on the OP - this issue is clearly widespread. And the fact that "thousands of RV's are using it" is in no way a guarantee that they are all airworthy. In my experience, 5052 is far more forgiving than 3003 both to fabricate and maintain. Even stainless is easier to get right than 3003.
So only speaking for myself, I don't consider the use of 3003 "foolish", but you better know what you are doing. And for what it's worth, I DO know how to fabricate tube assemblies... And I reserve 3003 for mock up work.
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.
Michael Robinson
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Harmon Rocket II -SDS EFI
RV-8 - SDS CPI
1940 Taylorcraft BL-65
1984 L39C
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03-13-2015, 07:33 AM
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Join Date: Aug 2010
Location: Wichita, KS
Posts: 1,958
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Andy, good catch and great decision-making. As painful as it might be now, re-making your fuel lines will give you peace of mind when travelling with your girls.
If you'd like, you're welcome to my Parker Rolo-Flare for as long as you need, and I also have a rather large roll of 3/8" 3003 tubing that I have no plans for. That is, if you're not planning to use 5052. I might even be able to deliver them to OWI.
I agree with others that 3003 is adequate, however 5052 does have much better fatigue properties.
You're lucky that you don't have a nosewheel model - re-making the lines from the tank to the fuel selector is no treat. Ask me how I know 
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Kurt W.
RV9A
FLYING!!!
Last edited by krw5927 : 03-13-2015 at 07:38 AM.
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03-13-2015, 08:30 AM
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Join Date: Oct 2005
Location: Estes Park, CO
Posts: 3,947
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RFT-37
The clutch break on the RFT-37 results in thin flares wider than spec. I called and asked about adjusting it and was told it was factory set and not adjustable.
I place the tubing in the jig per instructions but stop at about two turns past initial contact. Then a half turn back and forth to burnish and remove it. Make a few practice flares and document the number of turns. It's consistent after that. YMMV
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Larry Larson
Estes Park, CO
http://wirejockrv7a.blogspot.com
wirejock at yahoo dot com
Donated 12/03/2019, plus a little extra.
RV-7A #73391, N511RV reserved (2,000+ hours)
HS SB, empennage, tanks, wings, fuse, working finishing kit
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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03-13-2015, 08:45 AM
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Join Date: Jun 2005
Location: Federal Way, Wa
Posts: 264
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No root cause yet
If you look closely at the photos, the material is not too thin. What appears to be thin is just the sharp edge of the fracture hiding the rest of that section. But the other side of the fracture shows the actual thickness of the material.
However, the flair has been sheared. The flair starts out fine as a cone, but the turns and forms a cylinder for a while, then continues as a cone. This cylinder appears to be a shear failure of the material. The actual fracture occurs where the material has yielded the most.
Assuming that the flair was overtightened is jumping to conclusions. What could cause this sort of shear? Was the flair made to the wrong angle? what tool was used to make he flair?
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Brice
RV-9A 90897 FLYING
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03-13-2015, 08:52 AM
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Join Date: Jan 2009
Location: Chino, CA
Posts: 202
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I always double flare my lines, it's a mandrel that rolls the tubing inward slightly before actual flare, it increases the thickness of flare. have never had flare problems after 40 airplanes
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Jerry Scott
Rocket II
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03-13-2015, 09:27 AM
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Join Date: Jan 2010
Location: Denver, CO
Posts: 1,967
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What do you use to do this?
Quote:
Originally Posted by RV Jerry
I always double flare my lines, it's a mandrel that rolls the tubing inward slightly before actual flare, it increases the thickness of flare. have never had flare problems after 40 airplanes
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I have the Rigid 37 deg tool, which I have used to do my hard lines. Luckily, I haven't done that many (only the ones in the wings). However, I'm now reconsidering them and may go back and redo them with 5052. If the Parker RoloFlare doesn't have a clutch (i.e. you have to learn the right point to stop), couldn't the Rigid tool be used in the same manner? Then I would still have the "clutch feature" available for doing stainless steel tube later in the build..
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