Pitot static check...How?

How is the pitot static check done? The reason I'm asking is one the static line fittings I'm wanting to use are the push fittings that you basically just "push the line into. Similar to the Safe-air products. Fastenal has the "same" ones. I inquired about the properties and was shown that they are used in pressure and vacuum conditions. How would I check the units before I install them on my static ports? Under pressure (how much) or vacuum (how much)? I would like to bench test before installation.

The static leak check for an IFR certification is performed by applying a decrease in pressure (vacuum) equal to a increase of altitude of 1000 feet above field elevation and performing a leak down check. It should not leak down more than 100 feet in 1 minute. If you use push-in fittings make sure you are also using the correct tube for the fitting (same manufacturer) and making a clean cut without deforming the tube (do not use side cutters). SteinAir sells the complete system for resonable cost and also the tube cutter.

So you put a vacuum source on the static port?

Yup....then add the magic I...money!..i

BE VERY CAREFUL

putting vacuum or pressure on your instruments! Any change in pressure should be done in a very careful and controlled (SLOW) manner. If not you can easily damage your connected goodies.

I tested my system by rolling up some surgical rubber tubing and attaching it to an accessible line (tape over the static ports first). By carefully unrolling the tubing, you can create a controlled vacuum to raise the altimeter by 1000ft or so. Pinch it off with a hemostat, and watch for it to hold altitude or leak down. You can do the same thing on the pitot line by rolling up the tubing after attaching it to the pitot tube to create an airspeed reading (manometer works too).

I found lots of leaks in my system originally, and they all were at the instrument fittings. The tubing fittings worked fine (I used the standard nylon type with ferrules). Ended up using a tiny bit of sealant at all the instrument fittings.

Really glad I did this BEFORE taking it to the instrument tech for my pitot static test. It was $380 (including initial GRT calibrations) as it was with NO leaks...

No Instruments

Naturally I wouldn't connect to the instruments for testing. Basically I was wanting to bench test the "push to connect" fittings to see if they would hold vacuum or pressure at such a small amount of use. Most o-ring sealed fittings "seal" when the pressure pushes the o-ring in the housing and groove tighter in its assembly. My fittings (Fastenal aquired) look identical to others listed on this site and won't hold a vacuum for much time. Work fine under pressure. I have ordered the Safe-Air system and will test theirs also. Not sure if the press to connect fittings are the way go to get a leak free system for me. Or does it even matter at such a small amount of vacuum to have a leak on the static side?

Take a look here...

Here's a pretty detailed explanation of one way to test your pitot and static systems:

http://www.iflyez.com/manometer.shtml

We did this and found it to work well. It's a little trouble to set up the first time, but other builders in your area can use your manometer when you're done. The benefit to this is you can check your pitot system for leaks, your static system for leaks, and your airspeed indicator calibration.

We used one of those blood pressure cuff squeeze bulbs (my nurse wife says it's called a sphygmomanometer) that we picked up at a medical supply store. It was only a few bucks, and you can apply pressure or vacuum with it by hooking the surgical tubing up to the other end. It's a stretch, but it works. The squeeze bulb lets you carefully control the application and removal of pressure. We figured the few bucks spent there was a lot less costly than screwing up some instruments.

BTW, you're going to have to test the system when it's hooked up to your instruments, or you really haven't tested the system. As cautioned in the other posts, just go slowly--don't add or remove pressure quickly. Take your time, have a helper work with you, and you'll be fine.

Tbone said:

So you put a vacuum source on the static port?

Click to expand...

The avionics tech who does my RV-6A IFR cert every two years connects his vacuum system to my plane's alternate static port (in the cockpit), and seals the static ports with tape so the ports won't leak.

Tim Lewis said:

The avionics tech who does my RV-6A IFR cert every two years connects his vacuum system to my plane's alternate static port (in the cockpit), and seals the static ports with tape so the ports won't leak.

Click to expand...

Either one will work. Downside of this method is that you'll need an alternate static port or work loose one T behind the panel.

Even though we're not allowed to fly IFR in homebuilts here, we need to have a pitot/static port test performed every two years (at $$$, I might add). Rather than risking a leak and having to pay more $$$ for a re-test, I test mine thoroughly before the A&P shows up with his testing kit.

I found that taping over one static and sticking a fairly large syringe in the other works exceptionally well and will produce enough vacuum to get to a virtual 6000 feet or so, while providing enough control in order not to overstress any instruments (like VSI).

Just make sure that the plunger doesn't creep back in during the leakdown test.

I've found that it's relatively simple to get a 100% leak-free system. There's not a whole lot between the 100 ft per minute and leak-free.

Oh, and even though the instruments are clearly labelled "do not blow in instruments", this is exactly what a pitot is doing. Leaving the static open and putting the syringe and a couple of hoses to work on the pitot will leak-test that one nicely too.

FWIW.

Good luck!

Hans

VFR vs IFR Static Leak Down Rates

Can someone advise me if there is a different allowable leak down rate for VFR vs IFR? Are both 100'/min when altimeter is elevated 1000' above AGL?

Static line push fittings

Very bad experience with the Fastenal fittings. They leaked really bad and created hours of work chasing the leaks. Safe air fittings fixed all the leaks. Spend the money as it is a vital system and will save you money when the IFR check is done.
Get a professional shop to do the tests also well worth the money for IFR
Tyler
A&P FCC GROL
N174MT Flying

I bought fittings from both SteinAir and McMaster, and have had a great experience with them during both the initial build and during my recent panel update. It's a pretty tight system.

I also added "T" fittings with plugs so that I could do the leakdown check myself after taping off ports etc. A large syringe and a bit of tubing to plug into the ports let me test the system prior to paying for the real check.