BeechTalk - BT

Username Protected · **Posted:** 09 Feb 2021, 15:54

Cessna 182 S.

Had airspeed indicator indicator fixate at 100 kias in the climb. When I descended it initial went to the top of the green as expected, but not go below 100 in the pattern. It slowly bled off as we taxied in down to zero.

Is this due to blockage of a drain?

I do not see a drain on the pitot tube like a piper has?

Where is the drain?

Note it was very cold. Had been in non icing conditions both in flight and on the ground in heavy snow. Pitot heat, at least the top is working. My burn on my hand proves it!

Username Protected · **Posted:** 09 Feb 2021, 15:58

If the 182 is like the 185 there isn't a drain. It sounds like you have a blockage in the pitot line.

Andy

Username Protected · **Posted:** 09 Feb 2021, 16:02

Standard advice: never blow into a pitot tube or aim shop air at it; that's a good way to damage your instruments.

Suggest getting an A&P to disconnect the pitot line from the instruments and THEN determine if it's obstructed. Assuming it's not a chunk of ice, my first guess would be a pitot line got kinked behind the panel somewhere.

If the altimeter and VSI worked fine, I don't think it's a static block. Check pitot block first.

Username Protected · **Posted:** 09 Feb 2021, 17:38

Any harm in hooking a hair dryer up and heating pitot tube?

Username Protected · **Posted:** 09 Feb 2021, 23:57

-Static only frozen, descend and IAS is faster than you are flying.

-Pitot only frozen (not drain), IAS reading goes to ~0.

-Drain only frozen, IAS reads faster than you are flying (not sure about this one?).

-Pitot and drain frozen, descend and IAS is slower than you are flying.

-Pitot, drain and static frozen, IAS stays frozen.

Pick you poison.

Username Protected · **Posted:** 10 Feb 2021, 09:21

with pitot tubes iced over, plus the pitot drain holes plugged, and the airplane’s static sources unblocked: the airspeed indicator (ASI) effectively becomes an altimeter.

NWA 6231 B727 accident:
https://www.aviationsafetymagazine.com/features/pitot-static-system-failures/

Username Protected · **Posted:** 10 Feb 2021, 10:42

None of these explain my scenario exactly. That is what has me stumped. I believe my pitot line is partially blocked.

Username Protected · **Posted:** 10 Feb 2021, 11:13

The drain hole should be on the bottom, back by the bend. It's tiny, but it's there.

Did you try your alternate static port? Funny things happen if there is moisture in the line.

Airspeed indicator not functioning.