WAAS upgrade woes

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mhoran
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WAAS upgrade woes

Post by mhoran »

I managed to get my 2007 non-WAAS DA40 upgraded in September last year. Initially the upgrade was fine, but I started having some avionics gremlins a shortly after I got my plane back. On one flight I was advised by ATC that they were not receiving my mode C. There was no indication on the panel that anything was wrong with the transponder, but I noticed a TRAFFIC FAIL alert on the PFD. I cycled the XPDR breaker and ATC advised mode C showed up. Subsequent flights were without issue most of the time, but this issue came up intermittently every now and then. Recently, it started happening more and more often. I also noticed that it took longer to get a GPS fix on startup than I remembered. I was also getting backup GPS source alerts on the ground sometimes -- something I never remembered from before. These always resolved on the ground, so I didn't think much about it.

Finally managed to get the plane to the avionics shop this week. $2,400 in labor later, they told me there were a number of issues. First, they found a misconfiguration in the GTX-345. There were also grounding issues with the COM antennas. But the biggest issue: my ELT (ACK E-01) was causing significant RFI. So now I'll be upgrading to the ACK E-04 in the hopes that it resolves the RFI. Another $2,200.

Sharing my experience here in case anyone else runs into similar issues. My WAAS upgrade was performed at SouthTec and I was very satisfied. However, my avionics shop informed me that there should have been a RFI check done as part of the upgrade and that my plane would have failed the check. Not sure how that could have slipped by, but I'll be reaching out to SouthTec tomorrow to get their thoughts.
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Charles K
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Re: WAAS upgrade woes

Post by Charles K »

While I had some issues - they were different that you experienced and once corrected all has been mainly fine. All mine related to wiring boo boos. I would expect that your shop should have covered the GTX345 issues as that should have been a part of the upgrade/install.
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Re: WAAS upgrade woes

Post by mhoran »

I found that at least one other person seems to have encountered the same issue: viewtopic.php?p=38158#p38158. The "when transmitting on any com frequency near 121" bit seems to explain the intermittent behavior. I noticed near constant failure when doing some pattern work recently at my home airport (123.00). The first report of mode C failure happened when departing KPSM, where I transmitted on ground (120.95).

Unfortunately I didn't go back to SouthTec to troubleshoot the issues since that's a rather involved four hour flight plus return, instead going to the more local (though 1/4 of the way there) Lancaster Avionics.
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Re: WAAS upgrade woes

Post by mhoran »

It seems things certainly haven't gotten better, and may have gotten worse. I had a rather uneventful pickup from Lancaster Avionics on Friday, though I noticed for the first time a G/S1 SERVICE alert. I brushed this off when It went away after a power cycle. Everything seemed fine otherwise; I took off and made it back home without issue.

Tonight I went out to put things to the test. Immediately upon startup I got the G/S1 SERVICE alert. Ugh. I sure hope I don't have to replace my brand new (to me) GIA-63W. Then just as I was taking off, GPS1 dropped out completely. It wasn't until the downwind leg that it started to come back, and until i was on the ground that it was back completely.

Then there's the issue that brought me to the shop in the first place, the TRAFFIC FAIL alert. I saw this on downwind just as GPS1 was coming back online. I took a few more trips around the pattern and noted TRAFFIC FAIL on the taxi back four out of five times. The good (?) news is that it seems something is a bit different this time around; while I do see TRAFFIC FAIL, the ADS-B performance report indicates no failures.

So I guess I'll be making another trip to Lancaster...
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Re: WAAS upgrade woes

Post by mhoran »

Call for help: if you have a WAAS-enabled G1000 running software 321.23 and a TAS box, could you tell me if you see the following when you pull the TAS breaker after the system is fully up and running with no alerts:
1) TRAFFIC FAIL alert
2) GDL 90 X-out on system status page

I ran some tests last night to determine if GIA1 was to blame for the failures. However, I got a TRAFFIC FAIL alert with GIA1 powered down. Ruling out GIA1 as the cause I pushed the breakers back in. I found that the only error on the system status page was the GDL 90. I determined that I would get a GDL 90 failure when pulling the TAS breaker. I don't remember ever seeing TRAFFIC FAIL or GDL 90 failure when pulling the TAS breaker before the WAAS upgrade, which I've had to do sometimes to remove ghost traffic. I'm beginning to think there's some weird interaction between my GTX-345 and the TAS600 box.

I found viewtopic.php?p=67190#p67190 which talks about moving the XPDR breaker to the avionics bus. This seems like an unnecessary amount of surgery that wasn't necessary previously. I'm hoping there is just a misconfiguration somewhere, but maybe this is something to do with the 321.23 software.
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Re: WAAS upgrade woes

Post by mhoran »

Well I don't think it's a TAS issue anymore. I flew down to Lancaster on Thursday and they disabled the TAS box. I went out today and got TRAFFIC FAIL just after startup. So now something else is going wrong.

We also swapped GIA1 and GIA2 and the GPS problems seem seem to have followed GIA1 to the new location. It seems I may have both a bad GTX-345 AND GIA.
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Re: WAAS upgrade woes

Post by Boatguy »

Have you had any communication with SouthTec?
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Re: WAAS upgrade woes

Post by mhoran »

Boatguy wrote: Sun Jan 23, 2022 12:08 am Have you had any communication with SouthTec?
Unfortunately I haven't heard back from them on this yet. I sent over all the troubleshooting performed so far and asked for input nearly two weeks ago. I'll have to give them a call again next week.
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Re: WAAS upgrade woes

Post by mhoran »

Chatted with Glenn at SouthTec this morning. Unfortunately not much more info than I had before, but the mentioned that the transponder software may have been updated as part of the WAAS upgrade. Lancaster wants to exchange the seemingly bad GIA, so I'll likely go forward with that. Exchange pricing has gone up quite a bit in the past couple of years, that's now $2800. I didn't get exchange pricing for a transponder. Glenn did suggest reloading the transponder software again to see if that helps, so I may have them give that a shop before exchanging the transponder as well.
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Re: WAAS upgrade woes

Post by mhoran »

Heard back from Lancaster this afternoon. Exchange GIA is on order. An exchange GTX-345 runs for $1560. However, they spoke with Garmin and Garmin believes that the traffic fail issue is being caused by a momentary loss of heading information. Why this never clears out is a question nobody can answer (Garmin believes it should come back when heading comes back.) But Garmin did give us a test to run whereby we can determine if there is any sort of delay in heading information being sent to the GTX-345. This requires hooking up a laptop to the transponder, powering down the G1000 and then bringing it back online to see if heading information arrives at the transponder within 5 seconds. If there is a heading delay issue (Garmin referred to this as a "FPGA 429 delay") an auxiliary set of jumper wires can be run to apparently speed up the heading acquisition process.
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