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  #1  
Old 06-29-2022, 10:08 AM
Bobstern Bobstern is offline
 
Join Date: Nov 2021
Location: Metairie
Posts: 20
Default Fuel leak

I have removed a totally electric fuel system from my RV7A and have redone it to a Vans blueprint system with one mechanical pump and one electric pump. Once complete, everything was pressure tested with no leaks found. Now after 10 flight hours I have found leaks coming from the 90's where they connect to the fuel selector valve. When I was assembling this system, I could not fully tighten the 90's because they would be out of position to line up with the fuel lines coming from the tanks. There must be a simple solution to this I just can't think of it. Any help or ideas will be greatly appreciated.
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  #2  
Old 06-29-2022, 10:48 AM
Desert Rat Desert Rat is offline
 
Join Date: Aug 2018
Location: Wichita KS
Posts: 916
Default

Maybe a stupid question, but did you use a sealant on the threads? Flared fittings don't get any kind of sealer applied, but the pipe thread end needs a sealant on it or they will weep.

Also, if you are trying to clock those and decide you went too far, don't try to back it off even a little, because the threads deform when you tighten it down and it will absolutely be leak prone if you back it off.
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  #3  
Old 06-29-2022, 11:27 AM
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RV7A Flyer RV7A Flyer is offline
 
Join Date: Jul 2013
Location: US
Posts: 2,706
Default

Quote:
Originally Posted by Bobstern View Post
When I was assembling this system, I could not fully tighten the 90's because they would be out of position to line up with the fuel lines coming from the tanks.
I believe the general spec for NPT fittings is to thread until hand-tight, then go 2-3 full turns more. You should be able to line up the fittings with the tube.

I had a few (like on the brake master cylinders) that needed to go almost one full turn past finger tight, and yeah, it took some wrenching to get it there, and I was worried it was going to crack the boss, but none of them did.
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  #4  
Old 06-29-2022, 12:17 PM
TS Flightlines TS Flightlines is offline
 
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Location: Ridgeland, SC
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Bob----Brass imperial valve, or Andair with NPT bosses?
Tom
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Joint Venture with Aircraft Specialty
Teflon Hose Assemblies for Experimentals
Proud Vendor for RV1, Donator to VAF
RV7A Tail Kit Completed, Fuse started-Pay as I go Plan, on hold while we develop new products for RV builders
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  #5  
Old 06-29-2022, 12:46 PM
Bobstern Bobstern is offline
 
Join Date: Nov 2021
Location: Metairie
Posts: 20
Default Fuel leak

Brass fuel valve Tom. How are you doing? Have been sending prayers your way.
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  #6  
Old 06-29-2022, 05:28 PM
TS Flightlines TS Flightlines is offline
 
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Location: Ridgeland, SC
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HI Bob--- recovered enough to see you at OSH!!!
Mark on the valve where the 90*s need to point, remove them, reseal them, and then reinstall---snug then about 2 full turns + the amount to orient them. IF you go past that point before they are tight, go another turn.
Might be easier to remove the valve from the plane and lock in in a vise----easier than fighting it in the cabin.

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
RV7A Tail Kit Completed, Fuse started-Pay as I go Plan, on hold while we develop new products for RV builders
Ridgeland, SC
www.tsflightlines.com, www.asflightlines.com
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  #7  
Old 06-29-2022, 06:45 PM
Bobstern Bobstern is offline
 
Join Date: Nov 2021
Location: Metairie
Posts: 20
Default Fuel Leak

Tom, great news, I will definitely look you up at OSH. I ordered 2 new 90's thinking I may have ruined them by overtightening them then backing them out to situate their position for the fuel lines. What type of seal are you talking about? I did not put any seal on the fittings at all. BTW, your fuel lines were the BOMB! They made this job so much easier for me, thanks for providing such a great product and caring.
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  #8  
Old 06-30-2022, 05:07 AM
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Bill.Peyton Bill.Peyton is offline
 
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Location: St. Louis, MO
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I use Loctite 567.
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WARNING! Information presented in this post is my opinion. All users of info have sole responsibility for determining accuracy or suitability for their use.
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  #9  
Old 06-30-2022, 06:45 AM
TS Flightlines TS Flightlines is offline
 
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Like Bill says, Loctite 567 is what I use.
Tom
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Joint Venture with Aircraft Specialty
Teflon Hose Assemblies for Experimentals
Proud Vendor for RV1, Donator to VAF
RV7A Tail Kit Completed, Fuse started-Pay as I go Plan, on hold while we develop new products for RV builders
Ridgeland, SC
www.tsflightlines.com, www.asflightlines.com
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  #10  
Old 06-30-2022, 07:49 AM
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bjdecker bjdecker is offline
 
Join Date: Jun 2005
Location: Georgetown, TX
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Default Close...

I use Locktite 565, as called for in Section 5 of the more recent plans (Page 5-27).

TDS/MSDS here -- https://www.henkel-adhesives.com/us/...ctite_565.html

For grins/giggles compare to compare to 567

https://www.henkel-adhesives.com/us/...ctite_567.html

The 567 seems to be intended for more high temp environments (firewall forward perhaps?)

Locktite 565 holds up better (% strength) in the presence of Gasoline, Acetone, Brake fluid, etc. etc.
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