Baro loss with transponder disconnected

[AmphibFlyer]

After I removed my Becker 4401 transponder for repair last week, my D-10A stopped displaying any baro data. Altitude is locked at 1200 feet (or is it -1200?), there's no VSI display, and the Dynon autopilot's altitude control is inop. The transponder normally is connected to the Dynon serial to parallel interface.

Is that normal behavior?

Is there any way to restore the baro data until the transponder is repaired? I tried changing the setting at MORE > SETUP > MORE > ALTENC. Press FRMAT, but that makes no difference.

(Fortunately, I installed a backup altimeter.)

=Don Maxwell

 

[dynonsupport]

The EFIS gets its altitude from its own static port, not from any other device. So, first, make sure the static port isn't blocked. Popping off the plumbing will confirm that. If you vent it and it's still pegged low like that, we'll need to see the unit.

 

[AmphibFlyer]

The EFIS gets its altitude from its own static port, not from any other device. So, first, make sure the static port isn't blocked. Popping off the plumbing will confirm that. If you vent it and it's still pegged low like that, we'll need to see the unit.

Hm. I don't think it's a blocked static port because the analog altimeter uses the same static source, and it works fine. But I'll check it anyway, to be sure. My transponder should be back on Monday, so I'll see if re-connecting it to the altitude s-p converter fixes the problem. If not, then I'll have to wonder whether it was a coincidence that the D-10A's baro displays quit working immediately after I took the transponder out.

If it makes any difference, I'm running the most recent firmware update that was sent to the autopilot beta testers--5.A.3, I think.

 

[dynonsupport]

Well if there was a severe static discharge event, or potentially water that got into the unit, then just the act or working on things may have caused something else inside to break. A pretty rare thing with our products, but not impossible.

 

[AmphibFlyer]

Well if there was a severe static discharge event, or potentially water that got into the unit, then just the act or working on things may have caused something else inside to break. A pretty rare thing with our products, but not impossible.

The transponder came back this afternoon. I'll probably be able to reinstall it tomorrow and will let you know if that takes care of the D-10A problem.

 

[AmphibFlyer]

Rats.   I flew for 1.2 hours today at exactly "-1200" feet--meaning that reinstalling the transponder made no difference. The D-10A still shows the altitude as "-1200", regardless of the actual altitude.

When the D-10A starts up, the VSI digital display appears at the same time as the airspeed, AOA, etc. The VSI always says "000". Then it takes about 30 seconds more for the altitude tape and digital displays to appear with the "-1200".

Everything else appears to be working normally. The baro setting can be changed.  The autopilot HDG, TRK, and NAV modes seem to work, although I haven't tried flying with them for more than a few seconds. The ALT function tries to keep the airplane at 1200 feet.

The Becker transponder normally displays the enoder's altitude output; now it stays at "1200" no matter what the actual altitude is.

This "1200" thing began after I removed the transponder to be repaired.  There was no problem with the D-10A before that, even though the transponder had been dead for several flights. It seems likely that there's a causal effect, but I can't imagine what it might be.

Is there some setting in Setup or elsewhere that controls the altitude encoder or the serial-parallel converter and that I might change to fix the problem?

Or must I send it in for repair?

 

[dynonsupport]

There's no causal effect, except perhaps for electrical damage that may have occurred while working on the connections. As mentioned before, there's no chance that the transponder connection would be causing this. That connection is one way only: the EFIS sends altitude to the transponder, but there's no talk back from it. The ONLY thing the unit uses for its own altitude is the static port. So, if you've confirmed that the static port isn't plugged/pressurized, then we'll need to see your unit for repair. Give us a call at 425-402-0433 for an RMA.