AN MU2 ENCOUNTERS ICING RESULTING IN A STALL; SPIN AND A 4500 FT LOSS OF ALT BEFORE RECOVERY COULD BE MADE.

Narrative

STALL/SPIN DURING CLBOUT IN ICING CONDITIONS. APPROX 1 INCH OF ICE ACCUMULATION (BEFORE BOOT OP). AIRSPD APPROX 125 KIAS. RATE OF CLB APPROX 200 FPM. DEICE BOOTS IN OP; BULK OF ICE SHED LEAVING ROUGH PATCHES BEHIND. RATE OF ICE ACCUMULATION IN CLOUD TOPS WAS HIGHER THAN LOWER CLOUD AREA. ACFT STALLED AND SPUN TO THE L. INITIALLY THE SPIN WAS RECOGNIZED AND NORMAL RECOVERY WAS INITIATED. ACFT LOST APPROX 4500 FT IN 3-4 SPIN ENTRIES. ACFT WAS RECOVERED IN VMC AT APPROX 10500 FT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR SAID THAT DURING CLB INTO FORECAST ICING CONDITIONS; PUBLISHED PROCS FOR THE OP WERE FOLLOWED. ICING APPEARED TO BE LIGHT AND WELL WITHIN THE GUIDELINES RECOMMENDED TO VISUALLY EVALUATE ICING ON THE AIRFRAME. PENETRATION INTO THE ICING AREA WAS MADE AT THE RECOMMENDED 180 KTS DURING CLB. CLOUDS WERE NOTED TO BE THINNING WITH BLUE ABOVE. IN AN EFFORT TO REACH FOR THE BLUE SKY; AIRSPD WAS ALLOWED TO DECREASE TO APPROX 125 KTS JUST PRIOR TO THE INITIAL STALL. THE CAPT WAS THE PF. HE DID NOT APPEAR TO BE ALARMED BY THE ICING; HOWEVER; HIS EXPERIENCE LEVEL WAS APPROX 200 HRS IN TYPE. HE IS RPTED TO HAVE OPERATED THIS TYPE ACFT IN SIMILAR CONDITIONS WITH SUCCESS. THE COMPANY INVOLVED HAS SET A MINIMUM AIRSPD LIMIT OF 170 KTS IN ICING CONDITIONS.