Alternate Static Valve

larryj · #1 02-13-2011, 11:23 AM

One simple way to provide for an Alternate Static source is to run the primary static line to a pnuematic 3-port switch; have the primary port (primary switch position) feeding the instruments and the secondary port (secondary switch position) open to the cockpit. The common valves I've seen are brass, and I just didn't want the weight and look of brass; so I went looking. I found an all-aluminum-body 3-port toggle switch perfect for the above stated application and thought I'd pass it along: ARO valve #M251LS - G1130. I ordered mine from WW Grainger and their p/n is 3NB16. I received it yesterday and it is just what I was after.

SteinAir · #2 02-13-2011, 02:21 PM

Hi Larry,

I have one of those on my desk and while it's a fine valve, here are the reasons we decided not to stock it:

While it is aluminum, it actually weighs more than the little brass one we do stock, it's about 3 times the size (larger) and about double the price. While you'll still see a tiny little bit of brass sticking through the panel, the toggle is still chrome...a sharpie does wonders if you want to make the brass part black.

Anyway, it's not a bad valve that you have and will work fine (we've used them before) so it's not meant as a flame, just as a data point.

My 2 cents as usual.

Cheers,
Stein

Norman CYYJ · #3 02-13-2011, 05:36 PM

Two inexpensive ways to go. Both work well, a save some money and you will probably never need it.

1- use a small tee fitting with a cap on the tee which can be taken off.

2- cut the line with a pair of side cutters. A union can always be used for repair.

larryj · #4 02-14-2011, 10:46 AM

Darn Stein, I just should have talked with you first !! And I really like Norman's idea of just cutting the line - now that is "git-er-done" !!! Thanks guys.

miyu1975 · #5 02-14-2011, 11:07 AM

just make sure you have scissors or a pocket knife, may be tough using your teeth

Bevan · #6 02-14-2011, 11:07 AM

Another thing I like about the static switch, is that you can try it when ever you want (without something so drastic as cutting a line) and get a feel for the difference (error) it will cause. Adds some understanding to how sensitive the pitot static system is.

Bevan

kentb · #7 02-14-2011, 11:28 AM

Quote:

Originally Posted by Norman CYYJ

Two inexpensive ways to go. Both work well, a save some money and you will probably never need it.

1- use a small tee fitting with a cap on the tee which can be taken off.

The added benefit is to allow you to easily hook into the T for static check. I added the T to my pitot line also for testing.

Kent

Norman CYYJ · #8 02-14-2011, 11:41 AM

Years ago we were taught to smash the VSI if the static line got frozen over. But that is kinda hard to do with today's glass cockpits.

Ironflight · #9 02-14-2011, 11:46 AM

Quote:

Originally Posted by kentb

The added benefit is to allow you to easily hook into the T for static check. I added the T to my pitot line also for testing.

Kent

Exactly! And with the QD fittings (like Stein sells, among others) you can just put a plug in it - very easy to release if required, and a service point for those two-year checks.