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What do you use to check for pitot/static leaks?


Anticept

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Note that this isn't a request for a certified pitot-static tester, just something to test for leaks.

One of the requirements when working on the pitot static system, is that after the fact, it has to be leak checked. It doesn't need recertified unless an alteration was done, just leak checked, and the system is considered good.

I have been putting a brake bleeder on the system to draw pressure and monitor airspeed/static and watching the gauges to see if they hold steady for a minute, but it's very crude and tiring way and today's for real pitot static check made me realize I really need a better system for finding leaks.

I see differential manometers on amazon, will probably get one of those. The next question would be what a reasonable vaccuum or pressure pump would be?

I am thinking a syringe would be fine with a super small restrictor and valve. The manometer will help me locate the leak with a lot better precision, and the restrictor will help control the rate of pressure or vaccuum put on the system as to not damage instruments.

Looking forward to thoughts!

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I found something called a water manometer, and it's an old school way to very gently check for leaks, and it only takes some home depot tubing and a few fittings. The water column height translates to altitude after you adjust for temperature if you need that level of precision. Still trying to find a proper static port suction cup and pitot tube "condom".

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

http://www.rstengineering.com/rst/articles/KP89JUL.pdf

Calculation sheet for temp adjustment if you need it: https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0CDkQFjAC&url=http%3A%2F%2Fwww.kilohotel.com%2Frv8%2Frvlinks%2Fkp%2Fasi_cal.xls&ei=UdcmVJH1O8rIiwK0_4HIAQ&usg=AFQjCNGSB3vKBZFMc95S_oGoELIu5ARHtg&sig2=RNnuHtxGdOfv4w5chiz94g

It's also useful for SAFELY checking for leaks in other sensitive places, like fuel tanks!

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A large syringe used for things like TCP additives can work, if you have even the smallest leak it won't work. Be very careful , it's not hard to mess up an airspeed, altimeter, or autopilot. I've done hundreds of certifications in my repair station.  My guess is if you haven't had it checked in many years it will probably leak. It's much safer to use a  test box designed for it. If you do have a leak it can be very time consuming to find it. You need the volume capacity and precision valves of a test box. It would take me about 5 minutes to check.

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There's a leak. About 350 ft/min. And it appears to either be the AP or one of the standby instruments.

But the repair station doesn't have CTs in its op specs, so they cannot repair it. I have to do it.

And the barfield tester is crazy expensive, I am not even going to ask to borrow it, it's one of the newer models.

I like the water manometer idea because i can lift the tube and it will be a nice gentle way of adding and removing pressure, and its super cheap to do.

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There is nothing special about a CT, my repair station doesn't specify an aircraft type. They probably just don't want to do it, there's no money in it for them and you won't want to pay their fee.

At the auto parts store there is an oil Suction tank that uses a small line to go down an oil filler tube to suck out oil in a lawn mower. It is the perfect setup for checking a static system. You MUST have a precision needle valve on it and don't pump up to much vacuum,  only a very small amount. Watch the airspeed limits, it will go up with the altimeter, you only need 1000 feet on the altimeter. Try it on a spare instrument if you have one.

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I had to go round and round about this.

For standard aircraft it's pretty easy to get approvals to work on them as a repair station since everything is categorized, but special airworthiness isn't covered by that. It requires adding their own section to the ops manual and the whole thing is dumb

I had to help the repair station and the local FSDO reach out to a person that specializes in putting together that section so they could easily add aircraft types to it. The station amd procedures were added, and they had sky arrow added. My aircraft was never on that list for airframe repairs, they can do the pitot static test, but they cannot open it up.

I had the list of regulations and faa orders relating to all of this on an old email that doesn't exist anymore.

The whole thing was mind numbingly dumb, but that's lawyers.

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U can check the static as a mechanic as well. What you are saying makes no sense about a repair station, you don't need to be one and you don't need a list of aircraft. What they are telling you is bull. I've been doing this a long time. They just don't want to do it.

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I'm checking it for leaks yeah. Once i have it plugged, I am giving it back to them so they can do the pitot static check (the full 43 app E shebang) and transponder.

Got into this mess in the first place because of said leak.

As for the repair station stuff, it's not really important to me. Went through several people dealing with it, not just the repair station. I really didn't care to get too deep into it I just know that there were a lot of hands in that pot.

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You don't need a tight static for a vfr transponder check, it's not required. Some aircraft don't even have one. If you replace  or repair an altimeter or encoder you will need to in order to do the correlation check. 

I don't need any equipment to check a static system, none. But I'm not going to elaborate because someone will mess up their instruments. This is not rocket science,  it's basic mechanic 101.

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There's a misunderstanding.

I am doing my CFII checkride and I need the IFR checks done.

Order 8700.1, Chapter 8 states that aircraft with limitations may still be used for IFR training and testing under VMC, but they must have required instrumentation and checks done.

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Probably best to find a different repair station to do the checks and repair. If you can find a mechanic to fix the static first it will be much easier and cheaper to get done. Fixing a leaky static can get involved but not hard, just takes time. When I bought my CT the backup analog airspeed indicator had a case leak. A CT should only take an hour to analyze for leaks. Once I had a Cessna 340 take 3 days to fix, it was a real mess. I guess I find it all simple because I've been doing it so long and don't realize that others don't see it the same way. It used to be easy to find good experienced mechanics but things have changed and there aren't many that can do everything. 

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This morning, I ended up replacing all of the old tubes on the back of the instrument panel, trimming off the worn out ends on the lines running through the airframe, and cleaning and chasing threads on fittings and instruments. Put thread tape on the threads, reattached everything, pressure is holding now and I turned it back over to them.

Main reason I want a manometer is if I suspect a gauge is malfunctioning, I can actually *test* if it is. Not just for leak checking.

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  • 3 months later...

I’ve got probably  5kts error (slow) indicated on cruise than I think I should be… am trying the syringe method (being very very careful) to check if there is a leak.   So I pressurized the airspeed up to about 60kts and it falls quite rapidly… about a knot ever second … am I supposed to cover the static port or does our system have a drain I’m supposed to block during this test?    If not then I guess I have a leak 

43800C6E-BCA1-4AF4-A09D-0E71A3E90AD6.jpeg

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6 hours ago, cdarza said:

I’ve got probably  5kts error (slow) indicated on cruise than I think I should be… am trying the syringe method (being very very careful) to check if there is a leak.   So I pressurized the airspeed up to about 60kts and it falls quite rapidly… about a knot ever second … am I supposed to cover the static port or does our system have a drain I’m supposed to block during this test?    If not then I guess I have a leak 

43800C6E-BCA1-4AF4-A09D-0E71A3E90AD6.jpeg

IMG_9476.MOV

I have seen many pitot static tests by those who do not know the dynamics of it destroy airspeed indicators, altimeters, etc. It only takes a small slip in pressure or vacuum to exceed the limits of the instrumentation. Very precise needle valves are used to regulate the pressure and depending how you set up the test it takes some thinking. New equipment like EFIS systems, air data computers, and autopilots are very susceptible to incorrect pressures,  it's in the install manuals they are very specific about it. If you don't fully understand it don't do it, it can be very expensive.

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Spray the fittings in question with gas leak detector (or make some bubbly water) and spray / apply (small paint brush) to fittings in question........ re pressurize the system a few times....... do not over pressurize..... then look for a bubble around the fittings you have sprayed.......... inspecting the fittings while pressurizing makes it easier to see the bubbles form... it could also be the instruments glass front....

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3 hours ago, Tommy Mc said:

Spray the fittings in question with gas leak detector (or make some bubbly water) and spray / apply (small paint brush) to fittings in question........ re pressurize the system a few times....... do not over pressurize..... then look for a bubble around the fittings you have sprayed.......... inspecting the fittings while pressurizing makes it easier to see the bubbles form... it could also be the instruments glass front....

That is definitely not the way to do it. I've done this for many years owning a certified avionics shop and I thought I had seen everything but I guess not. I suppose it will be good for sales for Dynon, Garmin and instrument overhaul companies. I don't want to disparage anyone but if you don't know what you are doing don't tell others to do something that could cost them thousands. 

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That's how you do it, you work your way back till you get to the instrumentation. Plastic and nylon fittings shrink over time and leak. I had an IFR certification to do on a Cessna 340 and it took 2 days to replace and rework fittings. Static was required to be tight at 15000 feet of vacuum because of the pressurized cabin.

 

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Another noteworthy point is avionics shops may not be familiar with the 6mm size of FD factory teflon tubing, using plastic fittings on this may not mate up well to begin with.  I prefer the teflon tubing in factory 6mm size, and quality brass compression fittings.  Not as light as plastic, but screwing these into the instruments with a bit of sealant is bullet proof.

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4 hours ago, GrassStripFlyBoy said:

Another noteworthy point is avionics shops may not be familiar with the 6mm size of FD factory teflon tubing, using plastic fittings on this may not mate up well to begin with.  I prefer the teflon tubing in factory 6mm size, and quality brass compression fittings.  Not as light as plastic, but screwing these into the instruments with a bit of sealant is bullet proof.

I've been using silicone tubing for about 30 yrs for tubing to tubing connections and I use it with brass T connections and barbed fittings in intruments.  It will never leak even after 20 years. Silicone tubing will not deteriorate. 

20220723_152621.jpg

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