C414A ACFT ENCOUNTERED LIGHT ICING IN CRUISE. RPTR PLT HAD TO USE ALTERNATE AIR ON THE R ENG WHEN THE MANIFOLD PRESSURE STARTED DECREASING; BUT DID NOT USE WING ANTI- ICE BECAUSE THERE WAS NOT ENOUGH BUILDUP. TEMP INVERSION EVENTUALLY MELTED THE ICE.

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GOING FROM CGI-CRP; WX BRIEFING FOR THUNDER SHOWERS AND MODERATE ICING. FLYING A C44A WITH FULL DEICING AND ANTI- ICING. CRUISING AT 13000 FT AND PICKING UP A LIGHT AMOUNT OF MIXED ON THE LOWER PART OF THE LEADING EDGE BUT WITH ONE ODDITY -- ICE FORMING JUST ABOVE THE STALL WARNING SENSOR ON THE L WING. THIS ICE WAS STREAMING BACK THE LEADING EDGE. I ASSUME THIS WAS FROM THE HEATED STALL WARNING ALTHOUGH I HAD NEVER SEEN THIS IN ANY ACFT I HAVE FLOWN IN 55 YRS. WITH THE SMALL AMOUNT OF ICE ON THE LEADING EDGE; I LOST ABOUT 7 MI OF IAS. AGAIN ODD. THEN I STARTED LOSING MANIFOLD PRESSURE ON R ENG (L ENG OK). ADVANCED THROTTLE AND MIXTURE -- NO HELP. OH OH; INTAKE IS ICING UP; WENT TO ALTERNATE AIR. MANIFOLD PRESSURE RECOVERED AND I WENT ON MY MERRY WAY. NOT ENOUGH ICE TO USE THE BOOTS AND AIR INVERSION FINALLY DISSIPATED THE WING ICE; CLOSED THE ALTERNATE AIR AND HAD OK MANIFOLD PRESSURE. IN THOUSANDS OF HRS OF FLYING; I HAVE NEVER HAD TO USE ALTERNATE AIR OR HAD A LOSS OF THAT MUCH IAS WITH SO LITTLE WING ICE. WITH THE ICE STREAMING BACK FROM THE STALL WARNING; I SUSPECT I WAS PICKING IT UP ON THE LOWER PART OF THE WING. FLY LONG ENOUGH; AND YOU'LL RUN INTO MOST EVERYTHING.