geoffb Posted March 14, 2019 Report Posted March 14, 2019 Just received my GTX335 kit and am getting my ducks in a row for the install. No GPS currently installed in the plane so this is an addition of an antenna. My plan is to install the new GA 35 above the forward cabin. My question is, do I need a doubler for the fuselage skin? If so, is the Garmin part appropriate or do I need to make one to fit the shape of the cabin skin? Thanks Quote
carusoam Posted March 14, 2019 Report Posted March 14, 2019 There are a few pics of Garmin and aspen antennae farms around here that include details and layouts and distances between devices... Best regards, -a- Quote
RLCarter Posted March 14, 2019 Report Posted March 14, 2019 34 minutes ago, geoffb said: No GPS currently installed in the plane so this is an addition of an antenna. My plan is to install the new GA 35 above the forward cabin Following closely as I have GA-35 to install as well. Wouldn't installing above the forward cabin put it into the fresh air plenum? Also Mooneys have a row of rivets right down the middle forcing anything mounted on top to be offset to one side or the other which doesn't set well with my symmetrical world..... Quote
Culver LFA Posted March 14, 2019 Report Posted March 14, 2019 5 minutes ago, RLCarter said: Following closely as I have GA-35 to install as well. Wouldn't installing above the forward cabin put it into the fresh air plenum? Also Mooneys have a row of rivets right down the middle forcing anything mounted on top to be offset to one side or the other which doesn't set well with my symmetrical world..... I have my one of my gps antennas located there. The bar for the cage going right down the middle of the plenum is something to keep in mind. You can remove the panels on the plenum for access and the antenna can be placed left or right of center of the bar. You'll need a 90º connector on your antenna lead for clearance. Just make sure you double/triple check the fastener locations with the template to make sure you can install the antenna in the holes you drilled. Quote
RLCarter Posted March 14, 2019 Report Posted March 14, 2019 19 minutes ago, Culver LFA said: You'll need a 90º connector on your antenna lead for clearance. Just make sure you double/triple check the fastener locations with the template to make sure you can install the antenna in the holes you drilled. Yep, laid out the pattern on the 172 today, will drill the holes first thing in the morning after I recheck it again.....Pucker factor gets a little high when drill through the skin of an airplane Quote
geoffb Posted April 6, 2019 Author Report Posted April 6, 2019 Thread resurrection. Finally carved out time to do this. After looking, measuring, worrying, etc. I am looking at mounting the GA35 either adjacent to the baggage door, on the left side of the cabin, top centerline, over the baggage compartment. Or, over the hat shelf, right side of centerline. Either location is sufficiently removed from the COM antennae and either position allows for the install of another GPS antenna in the other location later. Any problems with either location before I start ripping out the headliner? Quote
Igor_U Posted April 10, 2019 Report Posted April 10, 2019 On 4/6/2019 at 9:22 AM, geoffb said: Any problems with either location before I start ripping out the headliner? I just completed my install the other day. I have installed the GPS antenna at the location you mentioned, just left of the baggage door about mid station. However, reason for this is my old GPS antenna is installed in front of baggage doors (but aft of the plenum) on RHS of the C/L and steel tube. I would suggest that location is you have no antenna in vicinity. Keep in mind there's a drain PVC tube from the plenum heading aft on LHS. Remove the headliner to have a look (might be able to lower aft end) and it will be clear where to put it. I would suggest installing the doubler as Mooney skin is very thin (like .020" or so). Any al 2024 sheet (.020-.040 thk) would do. Regards, Quote
Guest Posted April 10, 2019 Report Posted April 10, 2019 Skin doublers are the norm for antenna installations. Pick a location with the flattest profile to avoid distorting the either the antenna or the skin. Remember the etch, Alodine and prime the doubler and skin under the doubler. Clarence Quote
geoffb Posted April 17, 2019 Author Report Posted April 17, 2019 Thanks all. Igor, the location you mention is too close to my forward COM antenna, otherwise would have gone up there. Clarence, I thought I needed to etch and alodine, but not prime. Won't primer impact the electrical connection between the doubler and the fuselage skin and therefore the grounding of the antenna? Geoff Quote
jaylw314 Posted April 17, 2019 Report Posted April 17, 2019 39 minutes ago, geoffb said: Thanks all. Igor, the location you mention is too close to my forward COM antenna, otherwise would have gone up there. Clarence, I thought I needed to etch and alodine, but not prime. Won't primer impact the electrical connection between the doubler and the fuselage skin and therefore the grounding of the antenna? Geoff primer has the shear strength of peanut butter. Driven rivets should make an electrical connection no problem. I've always wondered whether this is an issue with pulled rivets. I'm guessing it's OK with Cherry rivets, but not non-structural pull rivets. Quote
MinneMooney Posted October 30, 2019 Report Posted October 30, 2019 My A&P and I are about to replace the Garmin GA56 with a new Garmin GA35. The GA56 has a rubber gasket covering the entire bottom to prevent water from getting to the 4 screws or the BNC connector hole. The GA56 has an o-ring (but no bottom gasket) that seals the TNC connector hole but nothing to protect the 4 screw holes. What have people been doing to keep water from getting to the screw holes? A&P mentioned RTV, but is there a corrosion concern with aluminum with the acetic acid in RTV? Quote
N201MKTurbo Posted October 30, 2019 Report Posted October 30, 2019 37 minutes ago, MinneMooney said: My A&P and I are about to replace the Garmin GA56 with a new Garmin GA35. The GA56 has a rubber gasket covering the entire bottom to prevent water from getting to the 4 screws or the BNC connector hole. The GA56 has an o-ring (but no bottom gasket) that seals the TNC connector hole but nothing to protect the 4 screw holes. What have people been doing to keep water from getting to the screw holes? A&P mentioned RTV, but is there a corrosion concern with aluminum with the acetic acid in RTV? I use tank sealant. CS3330 I think. Quote
EricJ Posted October 30, 2019 Report Posted October 30, 2019 9 hours ago, MinneMooney said: My A&P and I are about to replace the Garmin GA56 with a new Garmin GA35. The GA56 has a rubber gasket covering the entire bottom to prevent water from getting to the 4 screws or the BNC connector hole. The GA56 has an o-ring (but no bottom gasket) that seals the TNC connector hole but nothing to protect the 4 screw holes. What have people been doing to keep water from getting to the screw holes? A&P mentioned RTV, but is there a corrosion concern with aluminum with the acetic acid in RTV? Many shops use RTV. I think the main concern with it is that it can cause discoloration when repainting the aircraft. I've not heard of it causing any structural issues. Quote
RLCarter Posted October 30, 2019 Report Posted October 30, 2019 10 hours ago, MinneMooney said: My A&P and I are about to replace the Garmin GA56 with a new Garmin GA35. The GA56 has a rubber gasket covering the entire bottom to prevent water from getting to the 4 screws or the BNC connector hole. The GA56 has an o-ring (but no bottom gasket) that seals the TNC connector hole but nothing to protect the 4 screw holes. What have people been doing to keep water from getting to the screw holes? A&P mentioned RTV, but is there a corrosion concern with aluminum with the acetic acid in RTV? Instructions on my GDL-82 says run a bead of RTV Silicon around the GA-35 once it's mounted, so that's what I did. Quote
MinneMooney Posted October 31, 2019 Report Posted October 31, 2019 12 hours ago, RLCarter said: Instructions on my GDL-82 says run a bead of RTV Silicon around the GA-35 once it's mounted, so that's what I did. Thanks for the tip. I looked up the Garmin Doc. 190-00848-00, which is the GA 35 installation instructions. It does include the following caution: “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.” 1 Quote
RLCarter Posted October 31, 2019 Report Posted October 31, 2019 3 hours ago, MinneMooney said: Thanks for the tip. I looked up the Garmin Doc. 190-00848-00, which is the GA 35 installation instructions. It does include the following caution: “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.” I don't remember it having a "caution", once it was bolted in place I ran a very small (1/16") bead around it then ran my finger around to smooth it out and remove the excess Quote
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