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Fuel line bend radius

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cjhukill(at)cox.net
Guest

Posted: Sat Nov 17, 2007 4:31 am Post subject: Fuel line bend radius

I wasn't happy with the tight bends needed to get  the fuel lines out of the tunnel, nor did I want to use flex lines due to there  service lifespan. Instead I used 90 degree bulkhead fittings, going thru the  holes provided, but with .125 plates riveted over the holes, with the proper  size holes for the fitting. Makes a very nice looking transition.

 Chris Hukill

 winging it

   [quote][b]

dlm46007(at)cox.net
Guest

Posted: Sat Nov 17, 2007 5:05 am Post subject: Fuel line bend radius

like this?

   From: owner-rv10-list-server(at)matronics.com  [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Chris  Hukill

Sent: Saturday, November 17, 2007 5:31 AM

To:  rv10-list(at)matronics.com

Subject: Fuel line bend  radius

 I wasn't happy with the tight bends needed to get  the fuel lines out of the tunnel, nor did I want to use flex lines due to there  service lifespan. Instead I used 90 degree bulkhead fittings, going thru the  holes provided, but with .125 plates riveted over the holes, with the proper  size holes for the fitting. Makes a very nice looking transition.

 Chris Hukill

 winging it

 	  Quote: 	

href="http://www.matronics.com/contribution">http://www.matronics.com/chref="http://www.matronics.com/Navigator?RV10-List">http://www.matronics.com/Navigator?RV10-List

href="http://forums.matronics.com">http://forums.matronics.com

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Tim Olson

Joined: 25 Jan 2007
Posts: 2872

Posted: Sat Nov 17, 2007 6:30 am Post subject: Fuel line bend radius

That is a fantastic way to do it for those who insist on sticking with

the hard AL tubing.  Why anyone would try to fish those things through

and around with all the bends in it is beyond me.  Good job David.

The thing is, I found between 2 different orders of that tubing, that

just putting bends in some of it really stressed the tubing.  I know

it isn't that way all the time, but at least one coil I purchased

tended to become cracked and brittle when doing any sharper bends.

So when you add the task of bending and rebending slightly to get them

run as a single piece, it starts to get a bit spooky as to how tough

they'll end up.



Nothing against well-done solid lines, but I just feel better having

a good flex line that has fewer connections in it that may leak, and

that have the ability to flex a bit without cracking.



For what it's worth, on the gear legs for brake lines, I've now heard

from one very good and experienced builder that his started cracking

by the upper bulkhead fitting, and that another builder had his crack

and brake and his brakes fail down by the wheel. So I know without

a doubt that we had 1 brake failure on a -10 and 1 that was almost

ready to happen.  Then there was a person who's build-to-order

-10 had a hard line that was coiled around the gear leg and ran

next to a nut...but too close, so it laid against the nut and had

worn almost 100% through the tubing before someone caught it.

So, running these lines really requires care.  Our pool of flying

-10's seems yet too few to be seeing some of these things if everyone

is very careful, so the real message is, whatever you do, do it right

and do it safe above all else.



Tim Olson - RV-10 N104CD - Flying

do not archive

David McNeill wrote:

 	  Quote: 	
		   like this?

 

 ------------------------------------------------------------------------

 *From:* owner-rv10-list-server(at)matronics.com 

 [mailto:owner-rv10-list-server(at)matronics.com] *On Behalf Of *Chris Hukill

 *Sent:* Saturday, November 17, 2007 5:31 AM

 *To:* rv10-list(at)matronics.com

 *Subject:* Fuel line bend radius

 

 I wasn't happy with the tight bends needed to get the fuel lines out of 

 the tunnel, nor did I want to use flex lines due to there service 

 lifespan. Instead I used 90 degree bulkhead fittings, going thru the 

 holes provided, but with .125 plates riveted over the holes, with the 

 proper size holes for the fitting. Makes a very nice looking transition.

 Chris Hukill

 winging it

 

 *

 

 href="http://www.matronics.com/contribution">http://www.matronics.com/chref="http://www.matronics.com/Navigator?RV10-List">http://www.matronics.com/Navigator?RV10-List

 href="http://forums.matronics.com">http://forums.matronics.com

 

 *

 

 

 ------------------------------------------------------------------------

wcurtis(at)nerv10.com
Guest

Posted: Sat Nov 17, 2007 9:49 am Post subject: Fuel line bend radius

Ditto. I did the same thing.  I wished Vans would have made these holes 9/16 so if you wanted to go this approach they would be unchanged and drill out to 3/4 for the standard installation.  I made 1/16" oversized washers for both sides to use the bulkhead fitting.  I used a 45 degree bulkhead fitting however.



William

http://wcurtis.nerv10.com/ 



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wcurtis(at)nerv10.com
Guest

Posted: Sat Nov 17, 2007 12:01 pm Post subject: Fuel line bend radius

Let me add a contrarian (devil's advocate for John Cox) data point to this flexible line mania.  



My 1975 Cessna Cardinal RG has an electro hydraulic gear system with a combination of solid aluminum and flexible hydraulic lines.  For the solid lines Cessna used bulkhead fittings at most locations where the solid lines have to go through structure.  The only flexible line in the system is at the nose gear actuator where it is the only option.  



There are no known gear-up landing incidents in a 177RG due to loss of fluid as a result of failure of any of the solid lines.  There are quite a few known gear-up incidents as a result of failures of the flexible lines at the nose gear however.  Primarily this is because flexible lines are life limited and those RG owners neglected to change them out ever 5 years.  Teflon hoses are supposedly without a life limit but even those I would change out every 10 years.



Fuel lines are the same in the 177RG, LOTS of bulkhead fittings and NO flexible lines.  In the RG gear leg, (which moves unlike the RV-10 leg) the brake lines are hard for the straight portion and small flexible lines are used only on the upper swivel joint and lower from the solid lines to the brake actuator.



Cessna obviously feels that solid lines and bulkhead fittings are more reliable for fluid delivery than flexible lines.  Cessna service history, and my personal data points, seems to confirm this.  And while manufactures are typically motivated by cost, (flexible lines are more expensive) I don't think this is the case in determining the type of line to use for fluid delivery in their aircraft.  As always, YMMV.



William

http://wcurtis.nerv10.com/ 



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MauleDriver(at)nc.rr.com
Guest

Posted: Sat Nov 17, 2007 2:52 pm Post subject: Fuel line bend radius

I like those a lot.  I thought about the same approach.  May take it.  

Thanks David and Chris

do not archive



David McNeill wrote:

 	  Quote: 	
		   like this?



 ------------------------------------------------------------------------

 *From:* owner-rv10-list-server(at)matronics.com 

 [mailto:owner-rv10-list-server(at)matronics.com] *On Behalf Of *Chris Hukill

 *Sent:* Saturday, November 17, 2007 5:31 AM

 *To:* rv10-list(at)matronics.com

 *Subject:* Fuel line bend radius



 I wasn't happy with the tight bends needed to get the fuel lines out 

 of the tunnel, nor did I want to use flex lines due to there service 

 lifespan. Instead I used 90 degree bulkhead fittings, going thru the 

 holes provided, but with .125 plates riveted over the holes, with the 

 proper size holes for the fitting. Makes a very nice looking transition.

 Chris Hukill

 winging it

 *

 *

wcurtis(at)nerv10.com
Guest

Posted: Sat Nov 17, 2007 5:00 pm Post subject: Fuel line bend radius

Forgot I had a picture of this on my site.

http://wcurtis.nerv10.com/08fuselage/fuselage37l.html



William

http://wcurtis.nerv10.com/ 



------

MauleDriver(at)nc.rr.com
Guest

Posted: Sun Nov 18, 2007 5:41 am Post subject: Fuel line bend radius

This looks like a good way to stay with hard lines so I just ordered 

some bulkhead fittings to do it.  Thanks for the pic showing how the 

control system sits in there in the tunnel.



2 Questions - what is the second run of 1/4" tubing for?

Where did you get the aluminum washers?  Did you fabricate?



Thanks

Bill Watson

#40605

William Curtis wrote:

[quote] 



 Forgot I had a picture of this on my site.

 http://wcurtis.nerv10.com/08fuselage/fuselage37l.html



 William

 http://wcurtis.nerv10.com/ 



 ------

Tim Olson

Joined: 25 Jan 2007
Posts: 2872

Posted: Sun Nov 18, 2007 5:54 am Post subject: Fuel line bend radius

Bill...those are the brake lines.

Tim Olson - RV-10 N104CD - Flying

do not archive

MauleDriver wrote:

[quote] 

 This looks like a good way to stay with hard lines so I just ordered 

 some bulkhead fittings to do it.  Thanks for the pic showing how the 

 control system sits in there in the tunnel.

 2 Questions - what is the second run of 1/4" tubing for?

 Where did you get the aluminum washers?  Did you fabricate?

 Thanks

 Bill Watson

 #40605

 William Curtis wrote:

> 

>

> Forgot I had a picture of this on my site.

> http://wcurtis.nerv10.com/08fuselage/fuselage37l.html

>

> William

> http://wcurtis.nerv10.com/

> ------

wcurtis(at)nerv10.com
Guest

Posted: Sun Nov 18, 2007 6:38 am Post subject: Fuel line bend radius

For those that would consider the bulkhead fittings; 90 degree fittings are best for the Andair valve, and 45 degree fittings for the stock valve.



Since the bulkhead holes are 3/4 inches, you will have to fabricate 2 - 1 1/4" OD X 9/16" ID washers from 0.063" aluminum.



Bill,



If you click on "Next Picture" from the below link you will see the plumbing for the fuel transfer pumps that attach those second 1/4" fittings.  These pumps will transfer fuel from the wings tanks to a main tank behind the baggage bulkhead to maintain preset levels of 3, 5 or 8 gallons.  Under "normal" conditions engine is fed from this main tank.  If the pumps or electric should fail, I would revert to manual tank switching.



http://wcurtis.nerv10.com/9XOther/RV10FuelPlumb.pdf



William

http://wcurtis.nerv10.com/ 



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