Deducing Alt Static Valve Position

[kontiki]

Some airplanes like the PA-28 and DA-40 have a little T valve under the instrument panel that opens and closes the alternate static port.

It not clear if the closed position on the valve is with the T parallel with the aircraft longitudinal axis or parallel with the lateral axis.

These two airplanes don't use the same convention and if you change it up enough, it's easy to forget which one is which.

Is there a quick and dirty way to tell once you got it off the ground?

Seems like the indicated altitude would increase when it's open on pretty much on everything except maybe when the cockpit vents are open, but I'm reluctant to count on that.

Thanks,

 

[Skylane81E]

The PA-28 is fairly easy, it is the same as a fuel drain valve

 

[RV10flyer]

You are correct...in flight, with fresh air closed, your altitude will increase if switch is opened. Mine increases 200-300'.

 

[gismo]

If you can open a window in flight, doing so will register an altitude jump and associated temporary indication of a climb or descent on the VSI if the valve is open. If you see those symptoms in either position of the valve, there's a leak in your static system (which could be the valve itself).

 

[kontiki]

If you can open a window in flight, doing so will register an altitude jump and associated temporary indication of a climb or descent on the VSI if the valve is open. If you see those symptoms in either position of the valve, there's a leak in your static system (which could be the valve itself).

That sounds like what I'm looking for. Thanks