metal to plastic tubing connection

pa24 · #1 05-23-2007, 05:06 AM

I have run 1/4" metal tubing from the pitot to the wing root, but want to run 1/4" plastic tubing inside cockpit to the several instruments that require pitot feed since the instruments all have plastic connectors. What can I use to make a good connection from the metal tubing to the plastic tubing at the wing root. I am using the poly tubing supplied by Vans. Any suggestions would be appreciated. Thanks.

jsharkey · #2 05-23-2007, 05:46 AM

Try heating the plastic tubing in hot water before slipping it as far as possible over the metal tube. Finish to the metal. Make sure the joint area is well supported so that there is minimal if any tension load on the joint in service. It's what the Van's drawings show for the carburetor small drain hose that runs runs through the lower firewall flange.
Jim Sharkey
RV6 - Getting there!!

jsharkey · #3 05-23-2007, 05:50 AM

This what I meant to post

Try heating the plastic tubing in hot water before slipping it as far as possible over the metal tube. Finish by adding a couple of tightly twisted loops of safety wire around the joint to clamp the plastic to the metal. Make sure the joint area is well supported so that there is minimal if any tension load on the joint in service. It's what the Van's drawings show for the carburetor small drain hose that runs runs through the lower firewall flange. Simple, light and cheap - don't know how well it works yet though

Jim Sharkey
RV6 - Getting there!!

Oldgeezer · #4 05-23-2007, 06:10 AM

PA24
I used a Safeair pitot system that came with fittings but you could purchase a AN816 4D nipple that will screw into the An818 nut. One end of the An816 is 1/8 pipe thread, then purchase a 1/8 pipe female barbed nipple at your local Lowes or Home Depot plumbing section. The barbed end will give better protection from the tubing slipping off.

Oldgeezer
RV9A

jlfernan · #5 05-23-2007, 06:21 AM

Use one of these from Wicks Aircraft. Simple, cheap, painless.
Part no.262N-04

rv72004 · #6 05-23-2007, 07:19 AM

I used a rubber hose sliped on about 1.5 inch over the metal. Same with the plastic hose . must be a tight fit !. 2 cable ties per side will secure it. Seen this done before and if done properly will not leak. EJ

JonJay · #7 05-23-2007, 08:31 AM

Quote:

Originally Posted by jlfernan

Use one of these from Wicks Aircraft. Simple, cheap, painless.
Part no.262N-04

Yup, me too. The bulkhead fitting allowed me to secure it on a piece of angle to the side of the fuselage. Not that it needs to be, but I felt better having it secured and not flopping around in the wing root.
Works well.

Larco · #8 05-23-2007, 08:46 AM

A 259-N 04 insert would compliment the poly end of the connection. Larry

dan · #9 05-23-2007, 10:02 AM

Quote:

Originally Posted by jlfernan

Use one of these from Wicks Aircraft. Simple, cheap, painless.
Part no.262N-04

Have you had your system leak checked yet? Is that fitting designed for aluminum tubing? I didn't think it was...

Aircraft Spruce sells 1/4" ID silicone tubing designed for exactly what you need. It's intended to slip over the ends of two pieces of tubing, regardless of their material.

JonJay · #10 05-23-2007, 10:14 AM

Quote:

Originally Posted by dan

Have you had your system leak checked yet? Is that fitting designed for aluminum tubing? I didn't think it was...

Aircraft Spruce sells 1/4" ID silicone tubing designed for exactly what you need. It's intended to slip over the ends of two pieces of tubing, regardless of their material.

It works great for pitot. I had a very slow leak when tested before flying, however, my DAR determined that it was not an issue for pitot and could have possibly been the other fittings or the instrument istelf. I have three airpseed indicators including GPS. Spot on all three. It probably was not designed for aluminum tubing, but was recommended to me by a local, well respected, supply house and multiple other RV builders/users of said fitting.
I would use it again.