ASI issue - something is off

T

TxAgfisher

MEMBER

East Texas

• Aug 10, 2020

• #1

When I first flew this Cub I was thinking the ASI despite being marked as MPH was actually indicating knots. However, it looks to me like the tube is bent upward and not getting all the air it should be. What is this secondary contraption under it? The picture is kind of blurry but you can see from level flight the tube is about 20 degrees above horizontal.

 

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skywagon8a

MEMBER

SE Mass MA6

• Aug 10, 2020

• #2

That is a bent pitot and static tube. Bend the entire assembly down until the upper one is parallel or slightly nose down in relation to the bottom of the wing. The lower tube should be lower and parallel to the pitot tube. That is the static port.

The pitot tube should be aligned within +/- 10 degrees of the relative wind.

 

BC12D-4-85

SPONSOR

Fairbanks, AK.

• Aug 10, 2020

• #3

And after you realign the tubes leak check the pitot tube. Slip a rubber hose tight over the open end then pinch it off and roll it up some. Watch the airspeed for an increase (from more air pressure in the tubing) and whether it holds indicated airspeed/pressure. If it bleeds off fix the leak. Leak = low indicated airspeed.

Gary

 

JWE

FRIEND

NC30

• Aug 10, 2020

• #4

Do NOT blow in the airspeed tube!

 

BC12D-4-85

SPONSOR

Fairbanks, AK.

• Aug 10, 2020

• #5

JWE said:

Do NOT blow in the airspeed tube!

Click to expand...

Yes. Which is why a rubber hose slowly rolled up to create pitot pressure is safe. If it won't hold pressure find the leak with soapy water sprayed on the tune and connections.

Gary

 

S2D

MEMBER

Montana

• Aug 10, 2020

• #6

Or just insert the proper size phillips screwdriver into the hose to create airspeed.