Garmin 430 (non-WAAS) drops satellites

ksp_530

ksp_530

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KSP
The 430 on our newly acquired Grumman Tiger seems to be loosing GPS signal, especially during the approach phase. It acquires satellites quickly during the start up and generally holds fine. At times, it looses signal during the cruise momentarily. During the approach phase, it failed RAIM, and messages kept popping indicating no coverage, loss of signal, etc.

The plane currently at the avionics shop. The mechanic ran several tests on ground, and could not replicate the problem. The thinks that the antenna cable might be a culprit, but he didn't sound so sure. I was wondering if any of you have had a similar issue and how it was resolved. Thanks for your inputs in advance.
 
I'd consider sending it into Garmin for a WAAS upgrade, which replaces the guts and will most certainly fix the problem.
 
I have a non-waas 430 which loses position very predictably when I fly over a certain area just South of my home field. I have not experienced the same on an approach however. Any chance you are experiencing gps loss at a certain location? In other words, does it occur at multiple fields or just one?

Alternately:
poor ground of gps antenna
failing gps antenna
inadequate gps cable length.
emi from other avionics - try putting the 430 on the satellite page and then turn off other avionics, strobes, etc to see if there is any improvement.

My bet is try a different gps antenna and see if problem resolves.
 
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Makes me wonder what you are turning on during the approach phase...
Something that you habitually, or required by a check list, turn on when approaching an airport. Fuel pump? Landing light?
Does it go away and then come back? Landing gear motor?
Does it go away and then stay away?
 
dell30rb said:
Unless the problem is with the antenna/installation.
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New antenna is included in the installation, and possibly new cabling. Even if they use the existing cable, they'll test the cable and the connections.

Basically what I'm saying is it makes no sense to spend any money on repairs to a 430 that will leave it a non-waas 430.
 
Brad Z said:
New antenna is included in the installation, and possibly new cabling. Even if they use the existing cable, they'll test the cable and the connections.

Basically what I'm saying is it makes no sense to spend any money on repairs to a 430 that will leave it a non-waas 430.
Click to expand...

Yes, straight 430 parts are getting scarce (Which I'm sure is by design but it is what it is) and the warranty is much better on the upgrade. With ADSB looming, I wouldn't consider anything other than an upgrade if the 430 started acting flaky.

My avionics guy says the GNSes start getting tired after 10-15 years.
 
Do you loose the satellites after you checked for RAIM? I believe that is part of the checklist for the non-WAAS GPS's.
 
Brad Z said:
I'd consider sending it into Garmin for a WAAS upgrade, which replaces the guts and will most certainly fix the problem.
Click to expand...

The mechanic said the unit itself is OK. We just bought the plane, not sure we can cough up another $8k for WAAS upgrade yet.
 
Thank you all. The mechanic says everything including the antenna are good, it is the cable that causing the issue. He quoted $1000 in parts labor to replace the cable. That is why trying get some idea how others dealt a similar issue.
 
ksp_530 said:
Thank you all. The mechanic says everything including the antenna are good, it is the cable that causing the issue. He quoted $1000 in parts labor to replace the cable. That is why trying get some idea how others dealt a similar issue.
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I'm sure he's ordeing the correct type of cable that will be compatible with an upgrade, if not make sure he is.
 
I would also confirm that you are not getting interference from a Com or ELT antenna. There are clearance requirements for the GPS antenna from other antenna. I have heard of GPS drop-outs when a Com is transmitting.


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ksp_530 said:
The mechanic said the unit itself is OK. We just bought the plane, not sure we can cough up another $8k for WAAS upgrade yet.
Click to expand...

I just had it done. It's nowhere close to $8K. Try half of that. Depending on where you have it done.
 
ksp_530 said:
Does that include the Garmin upgrade cost + installation?
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Yes it does. Garmin is about $3200, depending on what you already have, labor can vary, and you may or may not need an annunciator (the shop found an inexpensive used one).

I had about $1000 of additional work done on my plane, so total cost for upgrade + labor + annunciator was ~4800.

YMMV.
 
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