Pitot Leak

[Matt M]

I am chasing down a pitot leak. It was found as part of troubleshooting my leaky static system which I got resolved. During the IFR cert the test box was having trouble keeping the airspeed under control as the altitude was raised for the check so we had to abort. After some troubleshooting over the weekend I found a few leaks - airspeed gear switch to airspeed indicator and the o-ring drain. Got both of those resolved. Now I am still seeing a leak from the pitot tube to where it connects to the drain. Going to do some more troubleshooting - either it's the pitot tube, connection from the pitot tube to the nylon line, or the line itself. Verifying the connection to pitot tube requires drilling out the riveted inspection plate behind the pitot tube. If I do end up having to replace the pitot line, how hard is this? Doesn't look there is much access to get the forward part of the wing where the line is.

 

Matt

[Ragsf15e]

Just now, Matt M said:

I am chasing down a pitot leak. It was found as part of troubleshooting my leaky static system which I got resolved. During the IFR cert the test box was having trouble keeping the airspeed under control as the altitude was raised for the check so we had to abort. After some troubleshooting over the weekend I found a few leaks - airspeed gear switch to airspeed indicator and the o-ring drain. Got both of those resolved. Now I am still seeing a leak from the pitot tube to where it connects to the drain. Going to do some more troubleshooting - either it's the pitot tube, connection from the pitot tube to the nylon line, or the line itself. Verifying the connection to pitot tube requires drilling out the riveted inspection plate behind the pitot tube. If I do end up having to replace the pitot line, how hard is this? Doesn't look there is much access to get the forward part of the wing where the line is.

 

Matt

You can get to it from the front inspection panels which are only screwed in. You will also have to take apart the pilot’s side lower interior panel to reach through to the pitot drain.  Are you pretty sure the drain isn’t leaking? That’s a susceptible part.

I just had my static test done and had similar results. The tech unhooked from the pitot tube and hooked up to a pitot line behind the panel to finish the test. So everything passed, and then we troubleshot the pitot line between the cockpit and the pitot tube. It turned out to be the drain leaking and just needed a few actuations and a little lube, and then it sealed good.

[Matt M]

2 minutes ago, Ragsf15e said:

You can get to it from the front inspection panels which are only screwed in. You will also have to take apart the pilot’s side lower interior panel to reach through to the pitot drain.  Are you pretty sure the drain isn’t leaking? That’s a susceptible part.

I just had my static test done and had similar results. The tech unhooked from the pitot tube and hooked up to a pitot line behind the panel to finish the test. So everything passed, and then we troubleshot the pitot line between the cockpit and the pitot tube. It turned out to be the drain leaking and just needed a few actuations and a little lube, and then it sealed good.

I am certain the drain isn't leaking. I spent 3 hours removing the side panel and interior and busting up my hands getting in there to replace the o-ring. I disconnected the line from the pitot tube to the drain and put my test pressure source into the drain and I had zero loss on both my airspeed indicators. Once I go from the pitot tube all the way all bets are off.

[Ragsf15e]

40 minutes ago, Matt M said:

I am certain the drain isn't leaking. I spent 3 hours removing the side panel and interior and busting up my hands getting in there to replace the o-ring. I disconnected the line from the pitot tube to the drain and put my test pressure source into the drain and I had zero loss on both my airspeed indicators. Once I go from the pitot tube all the way all bets are off.

Yeah, the access to that drain isn’t fun.  And did it really need to be riveted in?!

[EricJ]

FWIW, the pitot tube itself can leak, too, so it might be worthwhile to isolate the tube and the line to make sure it's the line and not the tube.    My tube went bad about six years ago somehow, but replacing it did fix the problem.

[Matt M]

7 minutes ago, EricJ said:

FWIW, the pitot tube itself can leak, too, so it might be worthwhile to isolate the tube and the line to make sure it's the line and not the tube.    My tube went bad about six years ago somehow, but replacing it did fix the problem.

Yep, that will be one check once I get the inspection panel off behind it. Did you end up buying a new one or finding a salvage one? I looked and spruce has it for $2700. A little steep. Hopefully that is not it. If that is the case I will live with the leak. Not affecting airspeed indications at all. Got a workaround for the IFR cert to bypass it.

[PT20J]

The pitot tube has a small drain hole on the bottom. Make sure you seal it off when testing for leaks. Also, I found I had to seal my hose connection to the pitot with several wraps of tape or it leaked slightly even though the tube appeared to fit over the tube very snuggly.

[EricJ]

3 minutes ago, Matt M said:

Yep, that will be one check once I get the inspection panel off behind it. Did you end up buying a new one or finding a salvage one? I looked and spruce has it for $2700. A little steep. Hopefully that is not it. If that is the case I will live with the leak. Not affecting airspeed indications at all. Got a workaround for the IFR cert to bypass it.

In my case it happened during my avionice upgrade and they found it while doing the transponder/alt cert after the upgrade.   They found a servicable one somewhere for $750 and it's been fine.   I still have the old one, definitely leaks.   I don't know where they found the replacement but it saved a ton of money compared to new.

[Sue Bon]

I had to replace my pitot tube last year as it was leaking. Something to do with the pitot heat...?? It was easy to spot once they took the pitot tube out. Yours doesn't sound that easy.

$2700 is about $1000 less than I paid, before shipping to Switzerland.

[EricJ]

Just now, PT20J said:

The pitot tube has a small drain hole on the bottom. Make sure you seal it off when testing for leaks. Also, I found I had to seal my hose connection to the pitot with several wraps of tape or it leaked slightly even though the tube appeared to fit over the tube very snuggly.

Yeah, getting the tester to work right requires a piece of tape over the drain hole.   That should facilitate a leak check to isolate leaks as well.   The test tech would have known this.   It's tricky sorting out how to deal with the various pitot tube arrangements, like the mast that Piper uses, and some techs just disconnect those completely and connect directly to the lines and bypass the tube/mast/whatever.

[Matt M]

41 minutes ago, PT20J said:

The pitot tube has a small drain hole on the bottom. Make sure you seal it off when testing for leaks. Also, I found I had to seal my hose connection to the pitot with several wraps of tape or it leaked slightly even though the tube appeared to fit over the tube very snuggly.

That is what I am wondering. I used a 5/8" PVC tube over it and wrapped the drain port with electrical tape before the tube was on it and put a hose clamp around it. Seemed air tight. A couple of pieces of electrical tape seals off my static ports no problem.