Can the 430WAAS GPS Antenna fail?

[anthonydesmet]

Had an issue last couple weekends.  My 430W kept dropping satellites last weekend but would then come back for a while.  Today when I started up I had zero GPS satellites on the acquiring page.

i detached and reattached cable at back of unit and at the antenna. Also sprayed some contact cleaner.  No GPS satellites 
 

Then I swapped the #2 GPS antenna and put that cable into the 430W. Wall-a I now had GPS satellites. Put the 430 antenna in #2 GPS and as expected I had no satellites in #2 GPS.

So my question is….given the way this slowly failed, can our GPS antennas fail? I guess I’ve never heard of that. The antenna is a GA35. 

 

 

[KSMooniac]

Yes, they do fail.  Just buy another and you'll be fine.

[MikeOH]

I believe the GA35 is an active GPS antenna (requires power and contains an internal amplifier).  So, yeah, it likely has failed from your description.

[Skates97]

I may have one unopened in a box at the hangar. I can check this weekend.

[anthonydesmet]

15 minutes ago, Skates97 said:

I may have one unopened in a box at the hangar. I can check this weekend.

Thanks Skates!

[EricJ]

+1 that it is an active (powered) antenna with an internal amplifier, so the electronics inside it can fail.    The A-B swap test that you did appears to have confirmed that it was the antenna and not the cable or power supply to the antenna.

 

[anthonydesmet]

Thanks everyone! I didnt realize there was a difference between the GA35 and my other antenna. So also good to know that the antenna I plugged into my 430W from my 250XL is GPS only.

[anthonydesmet]

Hey, hopefully last question. I have the new antenna coming this week.  On the old antenna previous mech did a nice job with sealant around it. So after I peal off the old one, what do you guys recommend for sealant around new one? RV?

[N201MKTurbo]

15 minutes ago, anthonydesmet said:

Hey, hopefully last question. I have the new antenna coming this week.  On the old antenna previous mech did a nice job with sealant around it. So after I peal off the old one, what do you guys recommend for sealant around new one? RV?

I would use polysulfide. If it comes with a gasket, use that and read any instructions that comes with the antenna about sealing. 

[N201MKTurbo]

https://static.garmin.com/pumac/GA35GPS_WAAS-antenna_AntennaInstallationInstructions.pdf
 

Read section 2.5.7 about sealant. They specifically say that you cannot use RTV.

[anthonydesmet]

4 hours ago, N201MKTurbo said:

Read section 2.5.7 about sealant. They specifically say that you cannot use RTV.

Thanks!

[Aerodon]

On 7/7/2024 at 6:48 AM, N201MKTurbo said:

https://static.garmin.com/pumac/GA35GPS_WAAS-antenna_AntennaInstallationInstructions.pdf
 

Read section 2.5.7 about sealant. They specifically say that you cannot use RTV.

You got my attention so I looked it up.  My guys have always used 'aviation grade' Dow Corning RTV.

I think Garmin are trying to re-iterate not to use RTV from your local hardware store, and this applies to the rest of your airframe too.

 

 

>>Do not use construction grade RTV sealant or sealants containing acetic acid. These sealants may damage the electrical connections to the antenna. Use of these type sealants may void the antenna warranty.

[PT20J]

I think any "neutral cure" RTV would be fine. If you want to be explicit, MIL-A-14146A is the specification.  DOWSIL 3145 is compliant. That said, I know a lot of mechanics that use stuff from the hardware store in the engine compartment with no obvious ill effects. The acetic acid in original RTV is only an issue during cure, I believe. Still, it would be bad used around electronics. I wouldn't wash my circuit boards in vinegar.

[anthonydesmet]

UPDATE: received TSO’d WAAS antenna from aircraftspruce a couple weeks ago but today was first day I had a chance to fly and install.  Instructions talked about setting correct torque when installing but nothing about sealant so thanks to @N201MKTurbo for the instructions. I did use electric silicone sealant I found at ACE.  New antenna works 4.0.