Static Port Error - A Journey

[avrojockey]

Originally Posted by JCSmith

If you don’t mind, I’d really like to jump your post with a question of my own...
I’m having a similar issue, but my 6A indicated airspeed is reading around 7 kts FAST compared to an 8A and a F1 rocket in formation. After some research, I thought an error on the high side was due to a static leak. Did I misunderstand where the leak would likely be? I have the standard unset rivet heads.
I’d appreciate any suggestions.
Thanks!

One of the ways to quick check for a static leak - open and close your air vents, this will change the cabin pressure and you'll see a change in ALT,IAS,VS. A more detailed leak check includes a manometer attached to the static system, adding water to produce WC pressure and IALT decrease, then watch to see if WC or IALT changes after awhile. I'm doing this this afternoon.

[Bavafa]

Originally Posted by MacCool

Would a pitot/static leak test shed any light, maybe?

No, the pitot static leak will only show if you have a leak but not if there is any abnormal pressure at your static port during flight.

This has been well documented, for all RVs, the pop rivet shape yields the most accurate. For a better fitting and leak proof in a long term, the cleaveland static ports are the same shape but can be used with the fitting that makes them leak free in the long run.

[avrojockey]

So static system has a leak...somewhere.

It's a minor leak with 24"WC applied (~1800' below field elevation), it was dropping about 40'/min. I can only assume a proper test with vacuum to 18000' the rate would exceed 100'/min.

I'm going to get a hand vacuum pump from HF to do a proper vacuum test, find the leak and report back

[Walt]

Originally Posted by avrojockey

So static system has a leak...somewhere.

It's a minor leak with 24"WC applied (~1800' below field elevation), it was dropping about 40'/min. I can only assume a proper test with vacuum to 18000' the rate would exceed 100'/min.

I'm going to get a hand vacuum pump from HF to do a proper vacuum test, find the leak and report back

The limits for an IFR cert (non-pressurized) are 1000' AGL with <100'/min.

[avrojockey]

Originally Posted by Walt

The limits for an IFR cert (non-pressurized) are 1000' AGL with <100'/min.

Thanks Walt...finally found it in 23.1325. Not sure why my original search yielded 18000'

[calpilot]

Some EFIS have airspeed calibration ability, some do not. Best way to determine accuracy is to
Fly heading 360, 135 knots or 155 mph indicated, write down your ground speed and true airspeed; do this again for heading 120 degrees, then for 240 degrees. Total both, divide both by three, and if there is a difference between the average true and average ground speed, check for pitot and static leaks first. Also, if you have an airframe static port, and you have a heated pitot, make sure the pitot does not also have a static port. In my case, with a Garmin G3X (no airspeed adjustment) was brought into "nuts on" indications with a .063 dam in front of the static port.

Regards,

Gary

[avrojockey]

So I got to beat myself up a little in the tail of the airplane. I decided that if I'm going to check for leaks I might as well replace the crappy vinyl tubing the builder used with 3 different splices. Also, I decided to add the second static port per plans. (builder only had one on left side)

When everything was finished, it leaked about 200'/min at 1000' AGL. I spent a couple hours trying to trouble shoot and find the leak, and you know what it ended up being? The tape I used to cover the other static port! Aluminum speed tape does not work! Once, I replaced it with another tape the altitude didn't budge a single foot....tight!