Home-made Pitot & Static check.

[Wicked Stick]

I'd like to check for any leaks in my Pitot and Static lines before riveting on my top skin and starting to bond the windscreen. [RV-8]

I'm looking for ways to provide pressure to the pitot system and vacumn to the static port so I can monitor the Altitude and Airspeed readings on my AFS 3500 EFIS.

It's my understanding that if I can get less than a 100 foot drop of altitude from 1,000 feet in one minute I'm good with the static lines and if I get less than 10 knots of airspeed drop I'm good with the Pitot.

What local "home-made" tools have others used to create vacumn around the static port and pressure attached to the tip of the pitot ?

[andrew phillips]

Here is the most crude method you will find. I tapped into the lines by inserting a t fitting and extending a long tube out to where I could reach it. For pitot I just blew into the tube and noted that both my steam gauge and my 3500 presented exactly the same numbers. For static, I taped over the ports then sucked out the air (with my mouth) until both my steam and efis read 1000 ' above the airport. I then folded over the tube and clamped it. It took more than 15 minutes to loose the 100'. I won't fly into airspace that requires a pitot/static check until I have someone do my test properly but I feel confident that my system is working since a have 2 separate instruments that agree for each test and the system seems leak free.

Also, you can search the site for manometer. You can build one and do a fairly accurate calibration of the system if you so choose

[USCANAM]

Originally Posted by andrew phillips

Also, you can search the site for manometer. You can build one and do a fairly accurate calibration of the system if you so choose

Dave
I've got a manometer in the hangar I use for setting the carbs on the Gold Wing that you are welcome to borrow
Jack

[Rockyjs]

Dave,
Here is a link to the one I made. It's been used by other pilots at our field. Very accurate! This will work for vacuum and pressure. I use a blood pressure ball to control the air.

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

[Wicked Stick]

Originally Posted by USCANAM

Dave
I've got a manometer in the hangar I use for setting the carbs on the Gold Wing that you are welcome to borrow
Jack

Thanks Jack, I appreciate the offer.

Originally Posted by Rockyjs

Dave,
Here is a link to the one I made. It's been used by other pilots at our field. Very accurate! This will work for vacuum and pressure. I use a blood pressure ball to control the air.

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

In the spirit of building my RV for recreation and "Education", I think I'm going to build the manometer from the link above and give that a whirl.

[flion]

I tested my pitot line with the same rig I used for testing the fuel tanks. I hooked a keg pump to the fitting inside the fuselage and secured a balloon over the pitot. When the balloon stayed inflated overnight, I knew there were no leaks in the system. Thus, I only had to worry about the connection at the instrument panel. Don't laugh, it worked perfectly.

[Wicked Stick]

I connected a hose over the pitot under the wing, and blew into it (slowly) until I reached about 180kt indicated on the EFIS (AFS 3500). Then I pinched the hose shut and capped it off. When trying to cap it, a little leaked out but once capped, it settled on 160kt. Then I waited a little over a minute and I only lost 2 knots. From what I was told by an avionics guy at a nearby field, this was well within spec. (10 kts in 1 minute is considered o.k.)(Cool, I'm way better than that.)

Next I tried checking the static line. I went and got a suction cup from the hardware store, drilled a hole in the middle, and glued it to a piece of clear rubber tubing. Then I covere'd one static port with electrical tape, and proceeded to slowly suck on the hose with the cup on the other port. Well, it had a big leak. Like a recent post, I too had leaks at the static port and side of the fuselage.
So, I crawled back into the "tunnel of love" (RV-8) and discovered I had forgot to use sealant where the line attaches to the port. (duh)
So, I removed the lines, coated everything with sealant, and put it all back together. Once dry, I checked it again.
It was good to go after that. The avionics guy says that at 1,000 feet you should have no more than 100 feet loss in 1 minute, so I was really happy cause I never saw it go down more than 10 feet in 3 minutes.

One question though, I notice that as I would suck and bring the altitude indication up, the airspeed would also go up with it ?????? Is that normal ?

[Kevin Horton]

Originally Posted by Wicked Stick

One question though, I notice that as I would suck and bring the altitude indication up, the airspeed would also go up with it ?????? Is that normal ?

Yes - the ASI measures the difference between the pitot and static pressure, and converts that difference into an airspeed reading. At sea level, under standard conditions, if you decreased the static pressure to increase the altitude by 1000 ft, the ASI should read 148 kt. If you took the altimeter up to 2000 ft, the ASI should read 207 kt. Obviously one could damage the ASI if the static pressure was decreased too much without also sucking on the pitot line. For example, if you sucked hard enough on the static line to take the altimeter up to 20,000 ft, the ASI would read 536 kt. Our ASIs aren't built to take that.

Also, be careful to release the vacuum slowly, so the ASI and altimeter innards don't get spun around too fast.

[Wicked Stick]

Thanks Kevin,

I was very cautious about the speed at which I let air pressure in and out.
The most I brought the altitude up to, was about 3,000 feet.
That's when I notice the airspeed was in the red zone and I brought it back slowly to 1,000 for the time check.

I'll have to do it again and note the airspeed at 1,000 and 2,000 to see what the indicated airspeed reads.
I currently have the plane here at the house, which is approx. 40 feet above sea level, and I could set the alt to a nearby airport's current reading when trying this. Or, should I just set it to 29.92 ?

[Wicked Stick]

Originally Posted by Kevin Horton

Obviously one could damage the ASI if the static pressure was decreased too much without also sucking on the pitot line.

Sucking on the Pitot ??? When flying/climbing the air pressure goes down in the static system the higher we go. The air speed forces air "in" the pitot tube. So, wouldn't I want to blow into the pitot instead of suck ? I'm confused now. lol,... Please explain for this non-rocket science guy that I am.