D100 wind error Qn for Tech support on last post

[DavidRose]

Our Garmin 296 is linked to our D100 (& Dynon OAT sensor) & we get a wind readout on our D100 (firmware 5.4)

It's all been working fine for a year.

Recently we've been getting clearly wrong wind readings. They vary from realistic ie 20kts & then can gradually change up to 60kts.

Yesterday when the winds aloft were about 15-20kts we got a displayed wind of 40kts.

We compare IAS to GPS Groundspeed as a backup but for example yesterday with an IAS of 90kts and a GPS groundspeed of 85kts the D100 indicated a headwind of 35kts!

We've checked the connections, all okay.

any thoughts?

 

[Brantel]

Re: D100 wind error

My first guess is that your compass needs calibrating. That would make the most impact on causing an incorrect reading.

Also your OAT probe needs to be accurate as well.

Then there is the IAS accuracy...have you checked that?

Lots of variables go into that wind arrow being correct.

 

[DBRV10]

Re: D100 wind error

Apart from the above, you need to compare your TAS to a GPS BOX test, to verify your IAS and TAS.

This will prove if you have a static problem.

 

[DavidRose]

Re: D100 wind error

recalibrated our compass.

static pressure seems fine.

IAS seems fine comparing D100, standby and GPS g/s.

OAT seems accurate compare to reported temps.

Dynon tech support have you any thoughts? Does it matter if the 296 is track up or Course up?

 

[dynonsupport]

Re: D100 wind error Qn for Tech support on last po

First, make sure you've got the TAS/DA/OAT info item up on the EFIS. TAS is the number that matters in this calculation. That might clue you in to what's going on. Just FYI - we're pretty confident that there isn't a problem with the winds algorithm (we've been down this road before), but there are a bunch of data points that matter here, specifically GPS ground speed, mag heading, OAT, TAS, IAS.

 

[DavidRose]

Re: D100 wind error Qn for Tech support on last po

Thanks I'll check those data points and see what I find.

Out of interest is the only feed that the D100 needs from my Garmin 296 the gps ground speed?

Is there a simple way of explaining how the D100 calculates the wind using the data points you mention?