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  #1  
Old 02-11-2022, 01:20 PM
74-07 74-07 is online now
 
Join Date: Dec 2016
Location: Greenville, SC
Posts: 683
Default ADS-B failures and didn't know it

To start, I installed a Uavionix tailbeacon two years ago. It tested perfectly right out of the box. Since there's no observable indication of failure, I monitored it by pulling a ADS-B performance report quarterly. All came back good (I thought) until.......this week. After finishing up a panel upgrade (tailbeacon and transponder were not touched) I decided to pull my quarterly report early just to make certain all was ok. It wasn't. I had excessive NIC errors. Started looking into it and discovered, among other things, a bad ground can cause this. In the meantime, I contacted Mr. Mike Akers at the FAA ADS-B office and asked him if he could pull an extended report (shows the reception overlaid on a google earth map). I've worked with Mike before and he is extremely helpful. He generated several reports and it was obvious that my failure was happening after takeoff and would correct itself after 5-10 minutes. Additionally, we discovered that I had had multiple failures over the last two years! By coincidence, the days I pulled the reports were not indicative of what the actual historical performance had been. I checked the grounds this morning and all was perfect. Next, I brought out the installation app and used the monitoring function to see just how long it took for the unit to get a good 3D solution. The result was almost six minutes! So, I started the airplane and immediately turned on the tailbeacon (nav lights) and switched the transponder to ALT. I waited for six minutes (no problem since I had to warm it up anyhow before taxiing). I then taxied out normally, did my run-up and took off. Upon landing, I waited an hour and then requested a report. The results were near perfect. Uavionix confirmed that in addition to the poor grounds, rushing the takeoff, without giving the unit time to come to a 3D solution, will generate failed reports. We'll see if my new procedure results in continued success.

So, from this exercise I've learned that just pulling a report every once in a while probably isn't a guarantee that all is well.I'm going to be requesting them monthly moving forward. Next, give the system 5-6 minutes with everything turned on before departing. Hopefully, this will prevent the nasty letter that was certainly heading my way.
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  #2  
Old 02-11-2022, 04:04 PM
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catmandu catmandu is offline
 
Join Date: Dec 2005
Location: Sierra Nevada
Posts: 1,058
Default

Another reason my Nav Lights switch stays on always (the primary being an indication of battery master left on).
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  #3  
Old 02-11-2022, 11:12 PM
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RV7A Flyer RV7A Flyer is offline
 
Join Date: Jul 2013
Location: US
Posts: 2,709
Default

Quote:
Originally Posted by 74-07 View Post
I brought out the installation app and used the monitoring function to see just how long it took for the unit to get a good 3D solution. The result was almost six minutes!
That's an *awfully* long time to get a fix, unless it's not storing either the almanac or the ephemerides and having to wait for them to be transmitted each time it starts up.
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  #4  
Old 02-12-2022, 12:01 AM
OKAV8r OKAV8r is offline
 
Join Date: Feb 2007
Location: Seattle
Posts: 270
Default Skybeacon app

Just a reminder, you can monitor the unit on your phone using the Skybeacon app during the first five minutes after power up, via wifi.
also, if you use a Stratus ADSb receiver connected to Foreflight, you can monitor the unit during the entire flight, by looking at "Ownship"
(map page, settings dropdown, select Stratus, select Ownship), with all pertinent data displayed color-coded, green-good, red-bad
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  #5  
Old 02-12-2022, 10:17 PM
FlyinTiger FlyinTiger is offline
 
Join Date: Feb 2009
Location: Gilbert, SC
Posts: 338
Exclamation Aquisition time

Flying with a friend now and then who uses a SkyBeacon. The plane has to be put in the same place every time he rolls it out of the hangar. Position acquisition takes up to 10 minutes...sitting in one place.

This seems troublesome, he is looking for solutions.
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  #6  
Old 02-13-2022, 03:17 AM
74-07 74-07 is online now
 
Join Date: Dec 2016
Location: Greenville, SC
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I've flown mine twice now since discovering the problem. I have let it warm up in front of the hangar both times for 5 minutes with the transponder on ALT. I pulled the report for both flights and they were perfect. I have a blind encoder and I didn't realize until recently that they have a heating element that also requires sime time to come up to operating temperature. The time required really hasn't impacted my operations as I'm usually waiting at the end of the runway anyway for the oil temp to come up.
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Last edited by 74-07 : 02-13-2022 at 03:19 AM.
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  #7  
Old 03-04-2022, 07:57 AM
Andrew Clark Andrew Clark is offline
 
Join Date: Mar 2022
Location: Whitefish
Posts: 5
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Here is a pretty comprehensive GPS troubleshooting guide from uAvionix website. It shows how simple installation issues can result in NIC issues. Understanding the issues is the fastest way to fix them.
https://uavionix.com/downloads/troub...%20Rev%20B.pdf
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  #8  
Old 03-04-2022, 10:18 AM
JDeanda JDeanda is offline
 
Join Date: Apr 2013
Location: Ventura, CA
Posts: 328
Default SkyBeacon, Too?

Hm. We have a UAV SkyBeacon on the wingtip of our RV-6. Should I watch for the same things?
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  #9  
Old 03-04-2022, 12:00 PM
BobTurner BobTurner is online now
 
Join Date: Dec 2011
Location: Livermore, CA
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Quote:
Originally Posted by 74-07 View Post
……turned on the tailbeacon (nav lights) and switched the transponder to ALT. ...
Another poster suggested leaving the nav light switch on, all the time. I’ll add, leave the transponder on ALT, all the time. That’s now the recommended procedure.
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  #10  
Old 03-04-2022, 12:01 PM
Andrew Clark Andrew Clark is offline
 
Join Date: Mar 2022
Location: Whitefish
Posts: 5
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uAvionix skyBeacon and tailBeacon are virtually the same units in different packaging. If you degrade the continuity of either the positive or negative wire of any GPS (not just skyBeacon or tailBeacon), the GPS will suffer. NIC, Navigation Integrity Catagory, is typically the first to degrade if the GPS is not getting sufficient power. This is by design. The GPS NIC failure is telling you "something is wrong, the integrity of position cannot be guaranteed, please fix me" Your PAPR extended report will show the GPS restarting over and over, or even terminating the flight inaccurately on the map.

GPS functionality is pretty binary. If it shows at any point on the report that the GPS is functioning with acceptable NIC/NAC values, the GPS is most likely good. If you see the NIC/NAC come and go, then you have an environmental issue (either GPS reception, or more likely power issue). GPS, like a lightbulb, will not burn out then come back on. If it goes out, it will stay out. If GPS is coming in and out, just like the light bulb analogy, look at the environment (bad switch, wire, ground lug, etc) and not the light bulb itself.

Hope this helps.
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