Lost Satellites on 430W & 530W units for 22 min.

[Mooney_Allegro]

I had a new Garmin 430W & 530W installed about 8 months ago and I've been noticing that on the 530W unit, I lose satellite signal at least once/month for about 1 min., then it comes back online.  The 430W never lost a signal during those times.  While flying 2 days ago about 75 miles east of KRDU flying to Atlanta, I lost signal for both the 430W and 530W units for 22 min above an overcast layer.  I immediately switched to the backup VOR and notified ATC.  I then called FSS and asked if they had any satellite outages and how was the RAIM for my area, and they said only satellite #24 is out of service and RAIM was good in the entire state of North Carolina, where I was and South Carolina for that matter.  I was the only aircraft reporting any issues in that area. 

I called Garmin tech support after I landed in Atlanta and they said the first step in diagnosing the issue would be to reset both units to the factory default settings.  They said that the satellites could corrupt both units and make them malfunction and lose signal.  They said if this doesn't work, then it could be an antenna problem.     Has anyone else with either a 430W or 530W experienced losing the satellite signals on a regular basis for either a short time or long time frame?  If so, what was going wrong?

Thanks

[KSMooniac]

David, I've had random outages on my 530W/430W combo over the last few months and have not been able to correlate anything.  I got the WAAS upgrade done 26 months ago and never experienced anything until this summer.  Usually it is just a minute or two with both units going out, but occasionally just one will go out.  Never for more than 5 minutes, though.  Traffic on the AOPA board indicates that it might be related to recent software upgrades, but I haven't upgraded mine this year.  I really have no idea what is happening, and fortunately it has not happened during an approach, yet.

[Mooney_Allegro]

Hello Scott, thanks for the good info. I'm working on version 3.2, which is not the most recent update available.  Did you contact Garmin to ask them about what could cause this issue?  I haven't reset my units because I haven't had time.  I have a bunch of user waypoints stored in the database, and I need to record the lat/longs for them before I reset the units as Garmin suggested.  I'll have time to do that this weekend and will fly possibly Sunday on a long x-cty and we'll see if it happens again.  I want to get this resolved before the warranties expire. 

[KSMooniac]

David, I haven't contacted them yet, and I think I'm on 3.0 or 3.1 software but am not sure.  I think there is a 3.3 out now, but I've been holding off on the update until more is known about the lost reception. 

[Mooney_Allegro]

Scott, keep me updated on anything you find out.  I'll do the same here.

[carusoam]

Is this related?

I had encountered outages with a portable Garmin unit (GPS 196).  It occured in the same place heading to Sun 'n Fun twice.  I happened to speak with one of the engineers (Antenna Guy) at the lowrance.  His quick response was "do you have Narco radios."   Apparently the high noise output of the radio blocked out the ultra low GPS signal.  The amount of noise is related to the frequency that is tuned in.  Whenever I lose the GPS signal, I found it would come back after frequency changes.  Of course, flying a mooney, once you lose the GPS signal it may be difficult to get back because you are moving too quickly.

Questions:  What other radios do you have that are from the pre-digital era?  Did you change frequency, then lose the signal?  Did you get the signal back after a change of frequency?   Did you only get the signal back after landing?

Sounds like an antenna, noise or grounding issue.  Best of luck.

 

[KSMooniac]

I'll add that I only have the 530W/430W in my plane and no legacy nav/coms.  The only "old" box I have is the KT76 xponder.  My 496 has not lost reception, even with the attached antenna, during my episodes so it is most likely not a RAIM issue.  I thought perhaps monitoring 121.5 on com2 might be part of the problem, but my last few flights I've not done that and still occasionally lost signals.

[rbharvey]

I had the same issue with an Ovation when I upgraded both 430s to WAAS. One of the new antennas was bad and Garmin/tech had a hell of a time figuiring out what was wrong. In the end it was the antenna, that was actually jamming the other antenna, causing both units (fully independent, yeah right not when you mount both antennas inches from each other)

The problem started as intermittent issues that I wrote off to the cell phone, poor GPSD reception etc. But eventually one day when I powered up the aircraft. nothing. Couldnt get a GPS signal on either unit. Unit had their almanacs wiped clean and came right up on the bench.  Upgraded to 3.1 at the time, everything looked great. Stuck them back in the plane, one unit was intermittent in getting a fix, the other flat lined at zero reception. Replace a bad antenna (Garmin covered that part) and never had an issue again. YMMV

 

[Mooney_Allegro]

I spoke to a different technician at Garmin today and he told me it's most likely a bad antenna that is creating an issue with the 2nd Garmin GPS antenna just like Bob Harvey suggested on the reply above.  The tech suggested that if it happens again where both GPS's lost reception, to turn off the one that went out first and see if the other comes back online.  He suggested flipping to the last page of the NAV Chapter and looking at the satellite page when this happens.  It sounds like this issue will get worse over time.

Also, when I lost signal for 22 min in both GPS's, I was talking to different approach control facilities, and monitoring 121.5 on the 430W.  The only caveman instrument I have is the KN64 DME, otherwise everything else is glass.  I did not change freq. when this happened, I was on one frequency.  Both GPS's came back online probably 5 min. after I switched frequencies.  It all started happening about 20 min. into a 2.5 hour flight in eastern NC. 

One of the first things the Garmin tech asked me when I spoke to him today was, "did you have your cell phone on"?  He said this will interfere with the GPS signals and could easily cause the units to lose coverage. I did not have my cell phone on though, it was off, so I know it's not the cell phone.  I spoke with Trek at Garmin, he seems very knowledgable. He said Garmin will pay to replace the antenna under warranty if that is the case, but he said they "should" cover labor, but didn't commit to it.  I'll fly the plane again on either Saturday or Sunday, so hopefully I'll get more data then. Thanks everyone for all the good comments, keep them coming!

[Chris White ex-N205KD]

We lost the GPS signal on our recently-installed 530W (installed March 2009) a number of times right after we put it in.  Signal would be gone 5-10 minutes.  Tim Mathison, the avionics tech at Gann, had me write down the freqs we were on when it went out.  Gave him the freqs, he installed some kind of filter, and we have not had a problem since.  Took about 5 minutes to fix and cost $0.00. 

From my very limited understanding, certain frequencies will interfere with the GPS signal, which the filter fixes. 

Make any sense to anyone?

See attached pic for the error screen on the 530W.

[Mooney_Allegro]

Hello Chris,

Good info in your post! I've flown my plane over the same route last week with no outages, and I'm doing the same again today.  Do you recall the frequencies which gave you the GPS outage trouble?  I'll try those same frequencies with mine and see if the units lose satellite signal.  Do you know if Gann Aviation installed the filters somewhere on the antenna or GPS units themselves?  Did the outage happen on those frequencies when you transmitted or just dialed them in?

Thanks for your help. I'm really trying to take care of these issues before the warranty expires. 

[Chris White ex-N205KD]

Just checked flightaware, and it looks like I missed you by a few minutes! 

119.15 for sure, looking at the frequency on the pic above.  I'm thinking most were in the low 120's range, but I can't find the sheet I wrote them on.  If this doesn't work for you, I can give Tim a call and get you more details.  Doesn't look like it's too much of a hike to go over to 9A5, if that's what it takes!

[Mooney_Allegro]

I flew the plane 10 hours in the last week, and the GPS lost satellite issue resurfaced once on the 530W for about 10 seconds.  I just spoke to Garmin today, and they said to try to transmit on frequencies 121.175, and 131.275.  The tech told me those are the worst frequencies to interfere with GPS signals, and to watch the GPS signal when those freq. are in use.  If the GPS signal gets worse, then it is a shielding issue.  I'll try those frequencies tomorrow and see what happens. 

[Chris White ex-N205KD]

I hope we're narrowing it down!

[Guest Anonymous]

There is another possibility looming over the horizon.  How many of you have seen or know about this?

http://www.avtoday.com/av/issue/cover/Fixing-GPS_35197.html

 

p.s.  I am not quite ready to throw away my old ARNAV GPS/loran yet.  It is still sitting on a shelf in my hangar.

 

RFB

[Jeff_S]

I had a similar issue when I put a 430W into my Warrior two years ago. The GPS would just cut out unexpectedly, and then come back in a few minutes.  It happened three times in flight and twice on the ground. We tried various filters to no avail. Finally the avionics shop master just swapped my unit for the one in his Comanche, and when he saw the same problem in his Comanche Garmin decided to just give me a whole new unit. That problem hasn't happened since. (However, the right-side knobs just quit working earlier this year, which required a return to the factory to fix. I try not to think about the quality control for a system upon which we place such importance!)

[j3gq]

Had the same problem in our 201 with a 430W. No signal (or integrity failure in Garmin's parlance) for 3 to 5 minutes happened every few weeks. Garmin said they had no idea, and that it had never happened with other units. They recommended software upgrades, setting changes, and the like. Nothing helped. When I asked them to keep me posted on similar problems reported by other customers they simply went silent. In the end I was almost ready to give up. Worse, it always seemed to happen when the unit was needed most: in IMC and just before arrival.

Garmin said they had never heard of such problems (this blog seems to prove otherwise). Then unit was exchanged.... More flight tests ... same old problem, GPS antenna replaced ... same. My brave tech tested and worked several days and nights ... then more flight tests. Until he disconnected my ELT antenna cable. Signals he said seem to go from the GNS430W radio -> antenna -> ELT -> back to the GNS as higher harmonics. When I expressed doubts he opened the satellite page, pushed the PTT and whoosh all sat bars went down within seconds. The longer he held the PTT the more the unit needed time to recover. The same trick without the ELT and pas de probleme.

I hope this report helps some of you saving money - AJ

[Mooney_Allegro]

A few weeks ago I had both Garmin GPS antennas  for the 430W/530W swapped out for Brand new antennas by Epps Aviation at PDK Airport under warranty. I was there just a few hours and have flown the plane now for about 7 hours with no loss of GPS signal issues.  When I was down at Sarasota Avionics a few weeks ago for another issue, a Navajo was there getting new Garmin GPS antennas for the same thing.  Seems Garmin does have issues with some of their antennas.  Garmin doesn't manufacturer these antennas, a 3rd party vendor does.  When I asked the Garmin tech about why hasn't the problem been fixed, he told me that the 3rd party vendor cannot find any problems with their defective antennas when bench checked.