Pitot system problem

TylerSC

TylerSC

Pre-takeoff checklist
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TylerSC
PA-28-140. On takeoff roll yesterday my ASI was dead. Aborted at rotation speed.

Blowing into the pitot did nothing at the indicator. I put a little heater under the left wing and left for a couple hours. When I got back, when I blew into the pitot the ASI would indicate airspeed, quickly going up to 100mph and more, but it came back down very slowly.

The plane is in an unheated hangar and it has been around or slightly below freezing here, but I can’t imagine how ice would have gotten in there. But the symptoms did change a little after heating the pitot. Or, maybe another kind of blockage moved with the blowing?

The tubes going to the ASI behind the panel look good.

Any suggestions to fix this?
 
NEVER blow into the pitot.

It could have been water (especially if you have a low spot in the tubing). It may have been some insect or whatever that moved along.

It's a lot more productive (and safer) to remove the line from the ASI and blow it out from that side.
 
TylerSC said:
PA-28-140. On takeoff roll yesterday my ASI was dead. Aborted at rotation speed.

Blowing into the pitot did nothing at the indicator. I put a little heater under the left wing and left for a couple hours. When I got back, when I blew into the pitot the ASI would indicate airspeed, quickly going up to 100mph and more, but it came back down very slowly.

The plane is in an unheated hangar and it has been around or slightly below freezing here, but I can’t imagine how ice would have gotten in there. But the symptoms did change a little after heating the pitot. Or, maybe another kind of blockage moved with the blowing?

The tubes going to the ASI behind the panel look good.

Any suggestions to fix this?
Click to expand...
 
shocked-lemur-face.png
 
I agree with Ron " NEVER BLOW INTO PITOT TUBE" how ever i have do so on several occasions
but with extream caution! to check system integraty. (also cleaed line with shop compressed air in oposite direction).
It does sound like you had frozen water, probably codensation. You all here probably allready know this problem and fix dosnt fall into the "preventive maintenance" column and also regulation dictates that any time a pitot static line is opened (except for aircraft that are provided with a drain valve and that is where its opened) a system check is requiered.
I only mention this for those that may not know this, although having a pilots license supose to mean you possess this knowledge but often some how it slips by.
 
Yeah, don't blow on it.

I've picked up little amounts of pitot ice in some odd conditions you wouldn't think you would, hitting the heat is always my first go to, of course make sure you look down the tube on preflight, I also like to always have covers on the pitot due to bugs, though this time of a year that's not as much of a problem.
 
As said, do not blow into the pitot tube.

To give you an idea as to how much pressure is needed to make an indication, I had to adjust my retract interlock system (prevent gear retraction until over 90kias). To do this, I attach a hose to the pitot tube and submerge the other end into a bucket of water. a few inches below the surface is all it takes to indicate 90kias.
 
Dave Palacios said:
column and also regulation dictates that any time a pitot static line is opened (except for aircraft that are provided with a drain valve and that is where its opened) a system check is requiered.
Click to expand...
The pitot line is distinct from the static system. If you open only the pilot line (to blow it out or whatever), a static check is NOT required.
 
There may be a drain in the low point of the pilot system that should be opened on a regular basis to clear system. I'd get someone with a pilot/static test box check it out.
 
The pitot shall not be blown ever.

The pilot shall be blown regularly.

YMMV
 
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