Narrative:

En route from seg VOR to lake henry VOR, the aircraft, a PA23- 160, entered the clouds at 9000 ft MSL. The temperature at that altitude was minus 18 degrees C. The plane was immediately in a heavy snow squall. Approximately 45 seconds after entering the cloud, I tried to apply carburetor heat to both engines. The control for the right engine worked correctly. The control on the left engine could only be moved approximately 1/3 of its normal travel. I informed wilkes-barre approach of my difficulty. I asked if they had pilot reports on the cloud tops -- they did not. They approved my climbing to 11000 ft MSL in an attempt to clear the clouds. Upon reaching 11000 ft MSL, the plane was still in the clouds. The plane had accumulated approximately 1/2 inch of rime ice. I asked for a deviation to the east to clear the clouds. My request to deviate to the east was denied. Wilkes-barre approved a descent to 5000 ft MSL to warmer air. During my descent, I was told to contact ZNY and that they had been advised of my problem. At 5000 ft MSL, the left engine carburetor heat control freed up. The engine failed to produce thrust. Fuel pressure was decreasing. I turned on the electric fuel pumps. The aircraft would not maintain 5000 ft MSL. I tried to bring the engine into proper operation by adjusting the mixture and throttle controls for the left engine. I requested vectors to the nearest airport. Center gave me a heading. At 4000 ft MSL, the aircraft was below the clouds and visibility was approximately 2 1/2 to 3 mi. I feathered the left engine. The aircraft would not maintain altitude on the right engine. The right engine lost power. The aircraft glided to a swampy area. I made a gear up landing into the swamp. My passenger did not receive any apparent injury during the landing, but I struck my face against the radios and received facial cuts. I learned from this experience, that when these atmospheric conditions (minus 18 degrees C and moisture) exist, and it becomes apparent that continued flight at present heading and altitude will cause the plane to enter clouds: 1) to immediately request an altitude or heading change that will keep the aircraft clear of the clouds if at all possible. 2) to continue flight in these atmospheric conditions to apply carburetor heat and lean the fuel mixture for optimum engine operation before entering the clouds. 3) if a large amount of carburetor ice is already present, avoid drowning the engine with a large amount of water at one time by modulating the carburetor heat on and off until the ice is gone.

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Original NASA ASRS Text

Title: OFF ARPT LNDG.

Narrative: ENRTE FROM SEG VOR TO LAKE HENRY VOR, THE ACFT, A PA23- 160, ENTERED THE CLOUDS AT 9000 FT MSL. THE TEMP AT THAT ALT WAS MINUS 18 DEGS C. THE PLANE WAS IMMEDIATELY IN A HVY SNOW SQUALL. APPROX 45 SECONDS AFTER ENTERING THE CLOUD, I TRIED TO APPLY CARB HEAT TO BOTH ENGS. THE CTL FOR THE R ENG WORKED CORRECTLY. THE CTL ON THE L ENG COULD ONLY BE MOVED APPROX 1/3 OF ITS NORMAL TRAVEL. I INFORMED WILKES-BARRE APCH OF MY DIFFICULTY. I ASKED IF THEY HAD PLT RPTS ON THE CLOUD TOPS -- THEY DID NOT. THEY APPROVED MY CLBING TO 11000 FT MSL IN AN ATTEMPT TO CLR THE CLOUDS. UPON REACHING 11000 FT MSL, THE PLANE WAS STILL IN THE CLOUDS. THE PLANE HAD ACCUMULATED APPROX 1/2 INCH OF RIME ICE. I ASKED FOR A DEV TO THE E TO CLR THE CLOUDS. MY REQUEST TO DEVIATE TO THE E WAS DENIED. WILKES-BARRE APPROVED A DSCNT TO 5000 FT MSL TO WARMER AIR. DURING MY DSCNT, I WAS TOLD TO CONTACT ZNY AND THAT THEY HAD BEEN ADVISED OF MY PROB. AT 5000 FT MSL, THE L ENG CARB HEAT CTL FREED UP. THE ENG FAILED TO PRODUCE THRUST. FUEL PRESSURE WAS DECREASING. I TURNED ON THE ELECTRIC FUEL PUMPS. THE ACFT WOULD NOT MAINTAIN 5000 FT MSL. I TRIED TO BRING THE ENG INTO PROPER OP BY ADJUSTING THE MIXTURE AND THROTTLE CTLS FOR THE L ENG. I REQUESTED VECTORS TO THE NEAREST ARPT. CTR GAVE ME A HDG. AT 4000 FT MSL, THE ACFT WAS BELOW THE CLOUDS AND VISIBILITY WAS APPROX 2 1/2 TO 3 MI. I FEATHERED THE L ENG. THE ACFT WOULD NOT MAINTAIN ALT ON THE R ENG. THE R ENG LOST PWR. THE ACFT GLIDED TO A SWAMPY AREA. I MADE A GEAR UP LNDG INTO THE SWAMP. MY PAX DID NOT RECEIVE ANY APPARENT INJURY DURING THE LNDG, BUT I STRUCK MY FACE AGAINST THE RADIOS AND RECEIVED FACIAL CUTS. I LEARNED FROM THIS EXPERIENCE, THAT WHEN THESE ATMOSPHERIC CONDITIONS (MINUS 18 DEGS C AND MOISTURE) EXIST, AND IT BECOMES APPARENT THAT CONTINUED FLT AT PRESENT HDG AND ALT WILL CAUSE THE PLANE TO ENTER CLOUDS: 1) TO IMMEDIATELY REQUEST AN ALT OR HDG CHANGE THAT WILL KEEP THE ACFT CLR OF THE CLOUDS IF AT ALL POSSIBLE. 2) TO CONTINUE FLT IN THESE ATMOSPHERIC CONDITIONS TO APPLY CARB HEAT AND LEAN THE FUEL MIXTURE FOR OPTIMUM ENG OP BEFORE ENTERING THE CLOUDS. 3) IF A LARGE AMOUNT OF CARB ICE IS ALREADY PRESENT, AVOID DROWNING THE ENG WITH A LARGE AMOUNT OF WATER AT ONE TIME BY MODULATING THE CARB HEAT ON AND OFF UNTIL THE ICE IS GONE.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.