spring in Airspeed Indicator pitot inlet?

As part of installing an EFIS into my RV-6A (and keeping original ASI), I am replacing all the pitot & static lines behind the panel.

I'm using Tygon tubing for it, and the Tygon didn't fit well over the AN fitting on the back of the ASI, so I unscrewed it to replace it with a poly barbed fitting. I was surprised to find a spring inside the fitting.

I don't see anything inside the ASI inlet that the spring would be operating against.

Does anyone know what this might be for? Is it required for something, or can I just replace it with my poly barbed fitting & get on with the install?

Fitting & spring:


ASI inlet:


thanks for any help,
brian

That fitting came out of your airspeed indicator?????? I would bet that spring is not needed. If the asi is the normal Vans unit, clean up the threads and inlet area and install your new nylon fitting and then test the system when done.

yep

Yes, it did come out of the airspeed indicator pitot inlet. Not very pretty, is it? I especially like all the gunky thread sealer all over the end of the spring. Looks like Permatex.

Did you try pulling the tube out shown in the second picture? Maybe the spring is what is making that part seal.

rocketbob said:

Did you try pulling the tube out shown in the second picture? Maybe the spring is what is making that part seal.

Click to expand...

The little tube inside the ASI pitot port appears to be either a fixed part of the ASI or it's well glued in - no movement at all. Do others' ASIs have this little tube in the port?

I would suggest that it may be a "tension" spring too keep the fitting tight???

brian said:

Do others' ASIs have this little tube in the port?

Click to expand...

No. None of the five that I have owned...........