Airpeed appears to be way off

[6643]

I suggest that rather than pressuring the system by " blowing" into the tubing that one purchase a Walmart inexpensive manual blood pressure cuff and use the rubber bulb with the thumb control and use it to control the applied air pressure to the system.

I just make a really long loop of plastic tubing. Lift the free end up until you get the desired difference in heights of the two columns. If you have a leak, the levels will slowly equalize.

[4004]

Agreed, "more than one way to skin a cat"! However, is that how you set the height/pressure increments to correlate with the different air speed increments. That less than $ 20 bulb, that one may already have, sure provides "fine tuning" the various heights.

[6643]

That less than $ 20 bulb, that one may already have, sure provides "fine tuning" the various heights.

I'm part Scottish. Mine's free!

But, yes, slowly lift the free end until you get the desired difference in heights, then read the ASI.

[8466]

Sorry about not responding to your responses. I've been busy the last few weeks. Thank you for your information. I will be looking into those tests.
Thayne

[8466]

Read Neal Wright’s article pertaining to this issue.

I read his statement in the archives:
"... to cabin static. They put out a letter to dealers (no owners allowed) which told the story above and after the noted serial number, only the airspeed indicator was hooked to a static port. The reality is...sometimes, the airspeed works better hooked to cabin static, too. The letter from Cessna ..."

So how do vent the airspeed indicator into the cabin...Just by disconnection the static line from the back of the airspeed indicator?

[8474]

Yes, thats all you need to do....

[8466]

Thank you.

[8466]

I’m gonna try first what Neal says. But after examination I see the static line is daisy chained airspeed then vsi then altimeter. So if I disconnect the airspeed will I need to put a plug on the line to keep the static line closed. See picture. The line branching off to the left is the line to VSI and altimeter.

[8474]

Yes you would have to plug it if you still want the altimeter and VSI to draw from the static port. However, both the altimeter and VSI will work just fine in these little airplanes with cabin static pressure.

[6643]

If it's easier, just disconnect all of them. It's not like you're going to be shooting an approach to minimums anytime soon!