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RV 7 Comms failure

Jonathan Alvord

Well Known Member
Just returned from a trip from Washington State to Martha's Vineyard with my wife for our 25th anniversary and the flight was nearly uneventful with the exception of loss of comms while descending down and entering a Class Delta Airport at State College PA. We were able to hear but could no longer transmit on the primary radio, and then when we did transmit the Auto pilot would do some wacky movements (Thus we had to disconnect auto pilot when talking to other.) I have a back up comm radio and it would transmit and receive just not as well. We were flying through some pretty good weather while maintaining VFR but the Rain was heavy at times. and we tried to keep the plan covered but when the canopy would be lifted the water would undoubtedly find its way in and drip on our legs in the cockpit. I did manage to pick up a handheld (Back up)from a friend and tried to get an avionics shop in Concord NH to take a look at it (they just said I would have to remove the SL30 and send it to the factory to get repaired when I returned home.) After arriving to Martha's Vineyard and the plane getting a chance to dry out the radio began working again, however the back up radio which, was not having issues, started to affect the Autopilot but would still transmit and receive. Not sure where to start! Should I pull the SL30 and send it in for service ($800 flat fee per Garmin but have to take to service center first.) I do have an appointment to get ADSB installed and can ask avionics guys in Oregon to take a look at it.
Additionally Transponder would occasionally stop transmitting and would have to be reset.

Where would you start? Personally I think the humidity got to the system and caused a short. (This is the only aspect of the design that I think was poorly thought out). I have tried to seal the leading edge but that is not possible with a tip up canopy.
 
The heavy rain and moisture penetrating you avionics bay might be the cause. I have a tip up and parked under the elements and once in a while I experience similar symptoms on my SL40. Usually after I forget to tape the front edge of the tipup and rain gets inside the cockpit and on the tray of the radio. It dries up quickly and transmission is crisp again.
 
The heavy rain and moisture penetrating you avionics bay might be the cause. I have a tip up and parked under the elements and once in a while I experience similar symptoms on my SL40. Usually after I forget to tape the front edge of the tipup and rain gets inside the cockpit and on the tray of the radio. It dries up quickly and transmission is crisp again.

Was thinking I will need to bring Saran Wrap and leave a squeegee outside the plane when I travel!

Jon
 
We carry a roll of 2” wide vinyl “Bundling tape” (check out Home Depot’s electrical aisle) in Louise’s RV-6 just to cover the tip-up seams (even under the canopy cover) if it looks like its goign to rain and the airplane is sitting outside. It has definitely saved the avionics from a watery death on more than one occasion.
 
In a friends RV7A tipup, we lost his radio once due to rain that got in during taxi that dripped on the radio and our legs. So for my plane, I went to Ace and got some clear thick vinyl the width of the exposed area between the panel and sub-panel to seal the area off. I taped the front portion with vinyl tape to create a rain seal, and used velcro on the aft side along the panel top angle for access. Taping around the hinges was a bit tricky, and I made sealed aluminum hinge 'caps' for behind the sub-panel to make sure any water stays aft of them. Now when it really rains, the water collects near the hinges only where it can't affect anything important for my panel.

I know there is someone that makes a really nice cover for that area, but the vinyl was really easy to install for DIY.
 
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