NO GPS reception for 10 minutes

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   I have had GPS reception problems on and off with my two 2018 IFD440s. In September 2020 they were finally exchanged on warranty (thank you Bryan Kahl!). 
The first weeks the new units seemed to work fine, then I saw I had the feeling that again it would take longer until I had a GPS lock-on/position. The logs i sent in one month ago showed no problems.

Now today I had ZERO GPS reception for at around 10 (!) minutes. AUX/SYS/GPS STATUS showed "Searching" and not even ONE GPS bar (also not even the outlines of the bars, just a black page. 

I recycled the Avionics twice, no change. "GPS FAULT" ... "DEAD REKONING" messages. 

When I almost wanted to taxi back to to the hangar the GPS bars started coming up, slowly. Never more six or seven, but it finally worked. 

After my landing after a flight of 1:30 I got another "GPS Failure" message on one unit, it came on, went away, came on again ...

Not nice ... and what can I do?

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D-EACY Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: 29 Dec 2018 Location: Munich Status: Offline Points: 92	Post Options Post Reply Quote D-EACY Report Post Thanks(0) Quote Reply Topic: NO GPS reception for 10 minutes Posted: 03 Jul 2021 at 2:27pm
	I have had GPS reception problems on and off with my two 2018 IFD440s. In September 2020 they were finally exchanged on warranty (thank you Bryan Kahl!). The first weeks the new units seemed to work fine, then I saw I had the feeling that again it would take longer until I had a GPS lock-on/position. The logs i sent in one month ago showed no problems. Now today I had ZERO GPS reception for at around 10 (!) minutes. AUX/SYS/GPS STATUS showed "Searching" and not even ONE GPS bar (also not even the outlines of the bars, just a black page. I recycled the Avionics twice, no change. "GPS FAULT" ... "DEAD REKONING" messages. When I almost wanted to taxi back to to the hangar the GPS bars started coming up, slowly. Never more six or seven, but it finally worked. After my landing after a flight of 1:30 I got another "GPS Failure" message on one unit, it came on, went away, came on again ... Not nice ... and what can I do?
	2006 SR22-G2 DFC90 IFD440

Gring Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 30 Dec 2011 Location: Kingston, NY Status: Offline Points: 720	Post Options Post Reply Quote Gring Report Post Thanks(0) Quote Reply Posted: 03 Jul 2021 at 5:52pm
	It can be an antenna problem. An antenna problem will take out ALL the GPSs in the airplane including iPads and phones. I would try turning on only 1 IFD and see if you have GPS problems. If not, then it points to the other IFD GPS antenna. Turn off the first IFD and turn on the second IFD. If you get a failure as you describe above, then you can suspect the GPS antenna is bad. It doesn't take much to ruin an antenna by tightening the mounting bolts/screws too much and cracking the internals.

D-EACY Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: 29 Dec 2018 Location: Munich Status: Offline Points: 92	Post Options Post Reply Quote D-EACY Report Post Thanks(0) Quote Reply Posted: 04 Jul 2021 at 4:02am
	Two iPhones and the iPad mini installed in the airplane had perfect GPS reception. The two antennas are pretty new, they were installed with the 440s: A GA36 and a COMANT 2580-200. I will still try to start one at a time and check if it makes a difference. I doubt it though ... Thank you! Edited by D-EACY - 04 Jul 2021 at 4:02am
	2006 SR22-G2 DFC90 IFD440

scotthess Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 30 Dec 2018 Location: Texas Status: Offline Points: 28	Post Options Post Reply Quote scotthess Report Post Thanks(1) Quote Reply Posted: 04 Jul 2021 at 9:26pm
	In case you are using any cheapo USB power adapters they can also create RF interference. Simple enough to unplug the adapter while monitoring GPS signal strength.

D-EACY Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: 29 Dec 2018 Location: Munich Status: Offline Points: 92	Post Options Post Reply Quote D-EACY Report Post Thanks(0) Quote Reply Posted: 05 Jul 2021 at 2:55am
	Thanks. I have a really good one from ANKER, but you never know. But i think it is unlikely because of the pattern in which this happens ... getting worse over time, both units fail the same moment and work again ten minutes later ...
	2006 SR22-G2 DFC90 IFD440

D-EACY Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: 29 Dec 2018 Location: Munich Status: Offline Points: 92	Post Options Post Reply Quote D-EACY Report Post Thanks(0) Quote Reply Posted: 13 Jul 2021 at 9:12am
	... one of my 2 IFD440s has now failed completely. That's already one of the exchange units I got last year. Screen went black, then white ... no way to get it running. Obviously a hardware failure.
	2006 SR22-G2 DFC90 IFD440

PA23 Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 12 Oct 2019 Location: MMU Status: Offline Points: 292	Post Options Post Reply Quote PA23 Report Post Thanks(0) Quote Reply Posted: 02 Aug 2021 at 11:48am
	keep in mind the WAAS GPS antennas are NOT passive, they have a powered amplifier built into them and they can go bad. I had one fail on me, it initially started as slow to acquire, I lost the GPS signal in flight, it would come back and then one day I lost the signal in flight an it never re-acquired. Not saying the antenna is your problem, but keep it in mind. PA23