Narrative:

Icing was forecast for the route from freezing level to 18000 in clouds and precipitation. Icing had been reported from 7-9000 ft by other aircraft. At our departure tops appeared to be lower than 7000 ft in a scattered to broken layer. We filed and were cleared to climb to VFR on top. We broke out briefly at 7000 ft and then entered a build-up where we encountered heavy icing, with an accumulation of 1 inch on the leading edges in less than 5 mins. Airspeed in the small aircraft decayed to 90 mph with an occasional stall buffet and moderate vibration from ice build-up on the propeller. With full power we requested and received an immediate clearance back to pdx. The descent was made at 2000 FPM and the ice melted off at 3000 ft. A landing was made at nearby troutdale airport without further incident. On landing we were told to call ATC. When the pilot did he was informed that a report would be filed with flight standards for 'flight into known icing.' I believe that this incident points out several problems. First, icing is forecast in this part of the country from oct to may. If interpreted strictly, no one would fly during this time. Because we made a prudent diversion, we face the threat of certificate action. I will be far more reluctant to ask for assistance in the future. We felt from the existing forecasts and reports and from our own observations that we would be above the icing conditions before any encounter. I will be more reluctant to fly in these conditions in a non de-iced airplane.

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Original NASA ASRS Text

Title: GA SMA ENCOUNTERED HVY ICING DURING CLB OUT FROM PDX. REQUESTED CLRNC TO RETURN WHEN PERFORMANCE DETERIORATED TO ALMOST A STALL.

Narrative: ICING WAS FORECAST FOR THE RTE FROM FREEZING LEVEL TO 18000 IN CLOUDS AND PRECIPITATION. ICING HAD BEEN RPTED FROM 7-9000 FT BY OTHER ACFT. AT OUR DEP TOPS APPEARED TO BE LOWER THAN 7000 FT IN A SCATTERED TO BROKEN LAYER. WE FILED AND WERE CLRED TO CLB TO VFR ON TOP. WE BROKE OUT BRIEFLY AT 7000 FT AND THEN ENTERED A BUILD-UP WHERE WE ENCOUNTERED HVY ICING, WITH AN ACCUMULATION OF 1 INCH ON THE LEADING EDGES IN LESS THAN 5 MINS. AIRSPD IN THE SMA DECAYED TO 90 MPH WITH AN OCCASIONAL STALL BUFFET AND MODERATE VIBRATION FROM ICE BUILD-UP ON THE PROP. WITH FULL PWR WE REQUESTED AND RECEIVED AN IMMEDIATE CLRNC BACK TO PDX. THE DSCNT WAS MADE AT 2000 FPM AND THE ICE MELTED OFF AT 3000 FT. A LNDG WAS MADE AT NEARBY TROUTDALE ARPT WITHOUT FURTHER INCIDENT. ON LNDG WE WERE TOLD TO CALL ATC. WHEN THE PLT DID HE WAS INFORMED THAT A RPT WOULD BE FILED WITH FLT STANDARDS FOR 'FLT INTO KNOWN ICING.' I BELIEVE THAT THIS INCIDENT POINTS OUT SEVERAL PROBLEMS. FIRST, ICING IS FORECAST IN THIS PART OF THE COUNTRY FROM OCT TO MAY. IF INTERPRETED STRICTLY, NO ONE WOULD FLY DURING THIS TIME. BECAUSE WE MADE A PRUDENT DIVERSION, WE FACE THE THREAT OF CERTIFICATE ACTION. I WILL BE FAR MORE RELUCTANT TO ASK FOR ASSISTANCE IN THE FUTURE. WE FELT FROM THE EXISTING FORECASTS AND RPTS AND FROM OUR OWN OBSERVATIONS THAT WE WOULD BE ABOVE THE ICING CONDITIONS BEFORE ANY ENCOUNTER. I WILL BE MORE RELUCTANT TO FLY IN THESE CONDITIONS IN A NON DE-ICED AIRPLANE.

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.