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Pitot tube icing


thinwing

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Last trip into BC fishing lodge I thought I had the fastest Bravo in the world!Climbing out of Nanaimo BC in moderate rain headed for 15 k all normal indications.Since I was out of IMC at 8 k I didn't have the pitot heat on nor anti ice.Approaching the coast mountains at 13 k I looked at the airspeed indicator on the g500 And saw it well past the barber pole indicating 275 kts while still climbing.Since I was in the clear well above rain clouds ,It took me a few seconds to think of ice in the pitot tube.Switching heat on ,the airspeed instantly read correct airspeed.I am guessing some water from earlier approach into Nanaimo got in to the pitot tube and later froze...isn't there a drain on bottom of pitot tubes to prevent this?Anybody else seen this behavior?

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Maybe your pitot tube was dry upon taking off and you just pick up a bit of moisture on the way up and it froze ? A good habit , turn ON the heat as soon as you are in visible moisture . No matter what . 

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10 minutes ago, Alain B said:

Maybe your pitot tube was dry upon taking off and you just pick up a bit of moisture on the way up and it froze ? A good habit , turn ON the heat as soon as you are in visible moisture . No matter what . 

That I do but this occurred 1/2 hour after climbing on top...my question was about that drain should have removed the water before climbing to freezing layer

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10 hours ago, thinwing said:

Last trip into BC fishing lodge I thought I had the fastest Bravo in the world!Climbing out of Nanaimo BC in moderate rain headed for 15 k all normal indications.Since I was out of IMC at 8 k I didn't have the pitot heat on nor anti ice.Approaching the coast mountains at 13 k I looked at the airspeed indicator on the g500 And saw it well past the barber pole indicating 275 kts while still climbing.Since I was in the clear well above rain clouds ,It took me a few seconds to think of ice in the pitot tube.Switching heat on ,the airspeed instantly read correct airspeed.I am guessing some water from earlier approach into Nanaimo got in to the pitot tube and later froze...isn't there a drain on bottom of pitot tubes to prevent this?Anybody else seen this behavior?

There are two drains on my pitot system. One being a small hole on the back of the pitot tube itself and the other is a drain located at wing root (near the front of the wing). I always push that one if I have been in rain.

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our pitot tube would clog in the lightest of rain or after washing. After drying out it would resume normal function. No safety wire or such would clean it out. Finally we removed the nylaflow connector inside the wing and blasted it out with 120 PSI shop air. A fair bit of bug debris came out, and since then, it works fantastic.  I'd suggest maybe trying that. 

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