J

Jonathan Alvord

Well Known Member
Ok Im in the process of getting the Plane recertified for IFR flight. What a pain it has been. Found that the altimeter was bad and needed replacing, tried buying a used one but that was not certifiable (was worse than the one I had). Then told I had a leak in the Autopilot (had to send it back to Mid Continent for repair, still waiting to hear from them). Was also told there was a leak in the static line anywhere from the Speedo back to the static ports.

I dove in and applied low pressure air to the static port and could not locate any air leak using baby power (recommended by avionics shop (should I be worried about cancer now? Just kidding). Whats the likely hood of a leaking line or poor seals in Steinair couplers? I'm tempted to just buy some new hose and replace it all.

Jon
 
had the same problem, but with the push-on 1/4" connectors the troubleshooting was fairly easy. Make some plugs by filling a short section of the plastic tubing with sealer so you can block off the system at any point. Start with the altimeter only and pull a slight vacuum (carefully! you can attach some coiled-up surgical tubing to the plastic tube and carefully uncoil it to reduce pressure in the line)) to get it to read a couple of thousand feet, pinch it off and note the bleed-down in feet per minute (Should be less than 100ft/min) Keep adding items (VSI, ASI, etc) until you find the problem(s)

ref:14 CFR Appendix E to Part 43 - Altimeter System Test and Inspection
 
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Some of those push on connectors seal far better in pressure than vacuum but they have improved very much in recent years but I would not be surprised if one was leaking a bit.
 
Bavafa said:
Some of those push on connectors seal far better in pressure than vacuum but they have improved very much in recent years but I would not be surprised if one was leaking a bit.
Click to expand...

I had several of the push on Safe-Air fittings leak when I built my RV-10. I even used the special tool they sell for cutting the lines clean and straight. Re-cut them all and they still leaked. Maybe better quality now but I ended up wrapping every joint with silicone fusion tape before I was able to get a leak free system. Not a big fan.
 
My first choice is Nylo seal, I do use the push on fittings sometimes but my go-to is always Nylo.
 
Bad Tee

Hard to believe but I finally traced the leak to the plastic Tee in the back between the two static ports.

Replaced that and the stiff plastic lines with thick-walled silicone vacuum hose. Also behind the panel.

Using any kind of stiff plastic (nylon, poly..., whatever) is asking for it, in my opinion.

Finn
 
Pitot/Static leak check

The August 2006 edition of Sport Aviation has a article, plans and instructions for a homebuilt Manometer that is unbelievably sensitive and will detect the tiniest leak. It even has a printable calibration scale to check your airspeed & altimeter.
Good for VFR but obviously not IFR but at least you can check for any leaks if you get suspicious of your readings.
 
FinnFlyer said:
Hard to believe but I finally traced the leak to the plastic Tee in the back between the two static ports.

Replaced that and the stiff plastic lines with thick-walled silicone vacuum hose. Also behind the panel.

Using any kind of stiff plastic (nylon, poly..., whatever) is asking for it, in my opinion.

Finn
Click to expand...

I think Van's used to (maybe still does) suggest heating nylon tubing and then pushing onto a nylon 'T', this method is guaranteed to crack the tubing after a few years.
 
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