Airspeed Doesn't Register on New D10A

jmaki

New Member
Joined
Apr 11, 2009
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3
Just flew my new D10A today. Two problems - first, airspeed did not register at all (stayed at 0). Pitot "t's" right of conventional AS indicator into Dynan, and AS indicator read normal.

Second the altimiter lagged quite a bit (static "t's" from Altimeter), reading ~200 feet low during climbout, and about 200 feet low in general, but then was back to proper ground elevation I had set when I landed.

I'll check pitot tomorrow to make sure it isn't blocked (can't imagine a brand new "t" and piece of tubing is). Assuming that is ok, is there some setting or calibration I haven't done? Or does this sound like a bad unit? Anything to do/try? I'll update after I confirm no pitot blockage.
 

dynonsupport

Dynon Technical Support
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Mar 23, 2005
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13,226
My first guess is that you have the lines swapped around on the EFIS. If I had to guess, you have pitot hooked to AoA and static hooked to Pitot. With this setup, pitot will read atmospheric (0 Knots), and static will read cabin pressure, which is often different than real static, but it's based on airspeed, so it will read perfect on the ground.

You can check the EFIS on the ground pretty easily with your finger. Take the tubing off the back, and put your finger over the airspeed port, and press. You can usually get 150-200 knots by doing this.
 

jmaki

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Apr 11, 2009
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3
Thanks for the incredibly fast response.  Feel silly - checked more carefully today and pitot and static crossed (installed by experienced avionics person!).  Didn't appear to be the case at first.  Now blowing into pitot gives same speed on A/S and Dynon.  Couldn't test-fly due to weather.  This won't have damaged unit, will it?

Also, noticed some interesting behavior when blowing into pitot.  The horizon pitch angle changes with airspeed, as does the magnetic heading.  Now these accelerations/decelerations are pretty extreme compared to reality, but just wanted to make sure this is the normal behavior.  Thanks.
 

DBRV10

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Jun 15, 2008
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Brisbane, Qld. Australia
for a start you should never blow in your pitot, or doing it very very slowly.

Otherwise you may break things.

And yes the rapid response from blowing in there might be an acceleration faster than an F16 so the poor little computer in there things the world is just about to spin off its axis :eek:

So what you are seeing is correct.......not normal ops either!
 

dynonsupport

Dynon Technical Support
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Mar 23, 2005
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Glad it was an easy fix!

As david says, the pitch change is expected.

You won't damage a Dynon EFIS by blowing in the pitot. The pressure sensors can handle much, much more than the human lungs can produce. I can't promise the same for all the steam gauges you might have though.
 

jmaki

New Member
Joined
Apr 11, 2009
Messages
3
Thanks for the responses.  Don't worry, I blew gently, slowly watching the "steam" A/S and never going much above 100 kts.  I just wanted to be sure having flown it with the ram pitot hooked up to the static didn't damage it via the static port.  And yes, I certainly created accelerations that even an F-16 couldn't match.  I look forward to trying it out soon, but am away for next couple of weeks, so I will just have to wait.
 
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