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Fuel line. dented flare

fazlo

Member
Hello all,
While removing the right-hand side fuel tank on my RV4, I dented the flare of the fuel line. I cut and redid the flare but it's now just a bit tight and susceptible to chaffing near the grommet. The fuel line goes in one piece from the tank to the Andair fuel valve. Instead of redoing the whole line (which is a complicated 3D exercise!), I am thinking of cutting it behind the fuselage wall, add a replacement tube, flare and use an AN815 union. Is it acceptable or would you advise to redo the whole line?
Thank you very much
Olivier
 
I suspect you may get different opinions, but that is what I would do. Properly done, it is quite safe. You want to support the union though, as it is more weight and want to avoid constant flexing of the lines attached to it. Best bet would be to make the union a bulkhead style mounted in the side exit penetration. You can make a small plate to pop rivet on over the existing 1" hole. However, that may be a real problem trying to flare that without a lot of bending.

Larry
 
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just re-do the whole line

Not sure how yours is done, perhaps some photos would help. If I had this problem on my -8 I would just redo the whole line - it won't take much time at all, and in the end it will be more secure. Perhaps there's a good reason to make it in multiple pieces, like access for example. Either way will be fine, but it's probably actually cheaper to just buy more tubing than installing a union.
 
I can't see your pictures (login required) so this may be off the mark, what about using a bulkhead union (AN832) where the line passes through the fuselage. Then the support would be built-in.
 
certainly you 'can' splice an end on there with a AN815-6D. But----by looking at the the tube and how it was originally formed, you 'might' consider redoing it---The tube passes through the snap bushing at an angle, and that should be avoided. Try to make the length of th etube beofr the bend long enough that you have a straight run through the hole. Much less chance of a rub, even with a snap bushing. IMO.

Tom
 
How about putting a bulkhead fitting on the web of that center tunnel? That way the section that goes out to the fuel tank would only be a foot or so long, and you could incorporate a slight ?S? bend so that your line goes straight through the fuselage skin to the tank. The ?S? would give you some latitude with the fit.
 
Thanks all for your suggestions.
Gil, I don't think I'd have enough space to fit in this otherwise interesting connection.
Well spotted, Tom! And I'll use Scott's suggestion (probably with an elbow fitting) should the redoing in one piece of this very curvy line with limited open access happen to be above my skills. Btw, is there anything I should read for techniques and tricks for making these kinds of lines?
Thanks again.
Olivier
 
Oliver---Tpubs of the Military are a good source. Might be alittle bit antiquantied, but still a good source.

Tom
 
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