ASI help needed and a question (water in the pipes?)
The problem started after some idiot left the pitot cover off for 10 days between flights.
In the pattern the ASI showed 110kts even when I knew I was slowing, on base it was still 110kts, I looked at the GPS and it was showing 70kts and it felt like it was 70. I landed OK.
I have photos of the ASI showing 80kts when I am on the taxiway stopped.
The ASI was rebuilt twice. The problem was still there. (many months passed)
After the second rebuild and seeing the problem again, it then disappeared. I never got a good answer from the mechanic on what he did to fix it. It worked fine for many months.
I did not fly since mid-December until the weekend before this (you can guess why).
The problem is back.
The mechanic is planning to send the ASI off for another rebuild.
I KNOW that will not help.
I just tested the ASI using a homemade manometer (¾” clear plastic tube in a U shape, one end on the pitot tube and poured water in the other end.
It did exactly what it is supposed to do.
It held steady for a few minutes and immediately fell to zero when I took the tape off the bleed port.
I am now suspicious there is water in the system and it froze that morning, it was 1ºC. I remember being surprised there was no ice on the wings, but humidity is needed for that.
It looks like 2” water = 70kts
I almost test flew it, but since I had reported a problem and it had not been signed off a mechanic I would be flying an illegal plane.
A high speed taxi down the runway would have worked, but the airport was a zoo on a Sunday afternoon and beautiful flying weather, so I did want to annoy everybody
The question:
If water gets into the pitot tubing, how does it get removed?
Eugene
PS
I am the only person that flys the plane
Comments
I have experienced a blocked pitot three times, but not from ice. In each case it was caused by insect intrusion in the pitot tube. I gently used an old-fashioned pipe cleaner or a piece of thin safety wire to clean out the pitot. One time the bugs brought in a bunch of dirt. In that case I disconnected the pitot line at the airspeed and put a vacuum on the pitot tube, to suck junk out of the line.
Do NOT suck or blow on the pitot to clear it with the A/S indicator connected, unless you want to buy a new gauge. DAMHIK.
From your panel photo I would imagine your aircraft is IFR certified. Your description appears to be a pitot-static problem, so whomever you go to for your IFR cert would be the place I'd go to for more questions. They would be the ones more likely than not to know how to troubleshoot and repair such issues.
Either that or you go up with a CFII and get some great experience with partial panel in your plane!
"some idiot left the pitot cover off for 10 days between flights" and "I am the only person that flys the plane"
Humility is a great virtue ... 👍️
Hmmm, I think I know this fellow. I see him in the mirror every morning, lol. :) You're among good friends!
Scott Sherer
Wright Brothers Master Pilot, FAA Commercial Pilot
Aviation Director, Cessna Owners Organization Forum Moderator and Cessna Owners Author.
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