I had a strange problem in my RV10 the other day. Was flying a long IFR XC in heavy rain and an hour into the flight got some static on the intercom. It gradually got louder and turned into a pulsating sound, about every second. A second loud click sound much faster rate then developed. Fortunately I could still hear ATC and they said my transmissions were fine. As this developed my mode C went crazy, altitudes from 1k to 27k. It all went away after sitting in a hanger for a weekend. This is the second time this has happened, only in heavy rain. Static instruments were all fine. I'm thinking some water must be getting in somewhere affecting avionics causing this clock-like noise; but what instrument would cause this and how do I find the leak?? (if there is one.)
Ideas?
Ideas?