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----- Original Message ----- From: "Ernest Christley" <echristley@nc.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Sunday, December 04, 2005 9:22 PM
Subject: [FlyRotary] fuel/brake lines fittings
Ed Anderson wrote:
No question you normally want to use fittings of matching metals. However, there has been some discussion about very small aluminum fittings (such as -3) not having much reserve strength (compared to larger aluminum fittings and of course steel fittings).
The Cleveland calipers I use come tapped for an (AN-4) - 1/8NPT fitting. I use this fitting to screw into the caliper. Then I use -4 Steel hose Fittings that mates with a -3 brake hose (strange I know, but they make them). Since the standard fittings for the Clevelands are the above mentioned AN -4 - 1/8 NPT fittings, I use the aluminum -4 fittings (NPT on one end) to screw into the aluminum calipers and screw the -4 steel hose fitting onto the AN portion of the caliper fitting. All the brake fittings on the RVs are -4(which I already had installed), so I stuck with that (except for the -3 hose). You can certainly use -4 lines, but I found them to feel a bit mushy for my taste and prefer the smaller -3 hose.
My 0.02 worth
Ed, can I get you to give me 0.03 worth? 8*)
I've order 3/16 (-3) aluminum tube for the 'middle' runs that will interface with well anchored bulkhead at both ends. The ends will obviously have to be flared connections. Are you saying there are aluminum fittings that will interface the -3 flared tube with -4 connections?
No, that is not what I intended to say {:>).
There are AN-3 aluminum fittings for flared aluminum tubing. You need a tube nut AN-819 and a tube sleeve AN-818 for a 3/16" line end. Then to connect that to your flexible -3 SS braided hose on one end you would need and AN-3 hose fitting and then ideally an AN-3/1/8NPT fitting to screw into your caliper. However, I used the AN-4 1/8NPT right angle fitting to screw into to my caliper because that is what Van provided with the kit. That is why I needed the strange AN-4 to -3 hose fitting in order to use the -3 SS braided hose brakeline.
On your bulkhead end, you would need a AN-3 fitting for the flare nut of the 3/16" aluminum line to screw on to. IF you are using the AN-4 fittings for your bulkhead and caliper fittings then there is no way I am aware of that you can use 3/16" aluminum line and have a AN-4 flare nut (at least I have not found any such adapter) , you would have to use 3/8" aluminum tubing. However, if you use -3 SS braided line from bulkhead to caliper then you can use the steel AN-4 /-3 Hose adapter and connect the -3 brake line to the AN-4 fittings.
Here is a source for steel AN-3/1/8NPT that could be screwed into the calipers and then you would be -3 all the way. There are AN-3 1/8NPT aluminum fittings but I have heard stories (no first hand evidence as I did not use them) that aluminum fittings that small do not have much reserve strength and I am hesitant to use them.
Here is the URL http://www.rjays.com/Brakes/brk-fttgs-01.htm check out the adapters part no. ALL50000.
Hope I have not confused the matter more
Ed
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