Static Port Design flaw

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Daneshgari
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Static Port Design flaw

Postby Daneshgari » Fri Sep 07, 2018 9:06 am

Hello All:

Has anyone's else experienced air speed indication variation by 10-20 KN in strong rain? In my not even one year old DA42VI I have to open the alternate static port in the cabine to avoid such fluctuations. I have checked with Diamond factory and they say that it is normal since the tubes and so very small and any water intrusion will cause blockage of the Static Port. Thoughts or solutions out there?

Thanks Perry
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Re: Static Port Design flaw

Postby CFIDave » Sat Sep 08, 2018 7:43 pm

Fortunately I never noticed this on my DA42-VI; maybe I just didn't fly in hard enough rain.

The DA62 has dual *heated* static ports on each side of the fuselage that the FAA required for FIKI de-ice certification, so I don't expect this to happen on my DA62.
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Re: Static Port Design flaw

Postby Karl » Tue Sep 11, 2018 2:52 am

We regularly fly in Monsoon rain and never have defect related to airspeed fluctuations reported.

I would suggest getting your mechanic to check the pitot/static system and any water drain valves to ensure there are no issues.
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Daneshgari
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Re: Static Port Design flaw

Postby Daneshgari » Tue Sep 11, 2018 7:15 pm

Thank you Kari. That is my plan when it goes for its annual this December.

Perry
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Re: Static Port Design flaw

Postby ultraturtle » Sat Sep 22, 2018 10:42 pm

Daneshgari wrote:Has anyone's else experienced air speed indication variation by 10-20 KN in strong rain?

While I've never experienced air speed indication variation in heavy rain, I have experienced as much as 10 knots of actual airspeed drop in heavy rain. It's to be expected as the magnificent efficiency of the DA42-VI wing is largely due to laminar flow, which is interrupted by any sort of contamination, such as rain.

Check your ground speed and TAS prior to a heavy rain encounter, and I'd bet that they both drop by about the same amount in the thick of it.

Then again, avoiding heavy rain might also be a good option to consider...
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Re: Static Port Design flaw

Postby Daneshgari » Sun Sep 23, 2018 2:15 am

Hi Rob:

Thank you for your feedback. I would agree with you if the plane’s behavior would not change after I open the alternate static source. I will be taking the plane to it’s annual next month. I am sure they will figure it.

Take care
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Re: Static Port Design flaw

Postby Daneshgari » Thu Oct 04, 2018 4:08 pm

Hi All:

one more info on this issue. I have included in my pre-fight an inspection and blowing on the static ports to get the water out before departure. It seems to help.

Perry
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Re: Static Port Design flaw

Postby neema » Tue Oct 09, 2018 6:48 am

Chiming in to add that that ours doesn't show much IAS fluctuation with rain. Only been in heavy rain for maybe a total of 30 minutes or so, but haven't seen those symptoms with any flying except windshear.
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rdrobson
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Re: Static Port Design flaw

Postby rdrobson » Wed Oct 10, 2018 3:20 pm

I thought of this post after flying through literally hours of rain on Monday night and Tuesday that in areas of rain in cumulus congestus clouds, you will see IAS fluctuations as the auto pilot is working to maintain a constant altitude.

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Re: Static Port Design flaw

Postby Daneshgari » Fri Oct 12, 2018 9:46 am

Hi Ron:
The way the factory explained it to me was the water entrapment in the bottom of the static port capillary, which then block the pressure differential comparison with the pitot tube static input. It could vary plane to plane. I will have them check mine in it’s annual and report back.

Perry

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