R WING STALLED REPEATEDLY DURING APCH DUE TO ICE ON THE WINGS.

Narrative

APPARENTLY OUR PROB WAS CAUSED BY ICE FORMATION ON TOP OF THE WING IN AN UNPROTECTED AREA AND COMPLICATED BY THE CRUISE PROP RPM SETTING; RATHER THAN ICING PROP RPM SETTING. A COMBINATION OF WORKLOAD AND FATIGUE PROBABLY CAUSED ME TO MISS PROPERLY SETTING THE CORRECT PROP RPM WHEN WE ENTERED ICING CONDITIONS. DURING THE DSCNT PRIOR TO RE-ENTRY INTO THE CLOUD LAYER THE FO RECONFIGURED THE ACFT WITH LEVEL 3 DEICING EQUIP ON. DURING DSCNT THE ACFT WAS CONSISTENTLY PASSING THROUGH PRECIPITATION OF VARIOUS INTENSITY. ICE WAS NOTED ACCUMULATING ON THE SIDE WINDOWS. THE OUTSIDE TEMP WAS FLUCTUATING BTWN 0 AND -3 DEGS C THROUGHOUT THE DSCNT. A ROUGH AIR PENETRATION SPD OF 180 KTS WAS BEING OBSERVED AS CLOSE AS POSSIBLE. EWR ATIS WAS 1600 BROKEN 2700 OVCST AND 1 1/2 MI LIGHT RAIN FOG AND SURFACE TEMP 38 DEGS; WINDS 080/26G45. THERE WERE MANY PLT RPTS OF ICING AT VARIOUS ALTS THROUGHOUT THE AREA. THERE WERE ALSO VARIOUS PLT RPTS OF WINDSHEAR OF PLUS OR MINUS 10 KTS. ICING SPDS WERE MARKED AND TARGET SPD WAS THEN INCREASED TO BE 129 KTS IN ORDER TO ACCOMMODATE THE TURB AND THE WINDSHEAR. CLRED FOR THE APCH BY ATC WITH RESTRICTION OF 180 KTS TO THE MARKER. PARTIAL GND CONTACT WAS OBSERVED. PASSING APPROX 7 NM AND APCHING THE FINAL APCH FIX THE FO BEGAN A PWR REDUCTION IN ORDER TO REDUCE SPD SO THAT THE ACFT COULD BE CONFIGURED IN THE NORMAL LNDG PROFILE. IT WAS AT THIS TIME DURING THE SPD REDUCTION THE AUTOPLT DISCONNECTED AND THE ACFT IMMEDIATELY ROLLED TO THE R AND AT THE SAME TIME PITCHED DOWN. THIS ALL OCCURRED QUICKLY AND AT ABOUT 2000 AGL. BOTH PLTS IMMEDIATELY GRABBED THE CTLS TO BRING THE WINGS LEVEL AND NOSE BACK UP. IT TOOK FULL AILERON TRAVEL TO DO SO. THE ACFT RETURNED TO NORMAL FLT AND WAS NOW BEING HANDFLOWN BY THE FO. SHORTLY AFTER; THE SAME FLT CHARACTERISTIC WAS OBSERVED AND THE ACFT ONCE AGAIN WAS RECOVERED. AT THIS TIME; THE TRIMS WERE CHKED AND FOUND TO BE NORMALLY POSITIONED. THE SAME FLT CHARACTERISTICS WERE OBSERVED FOR A THIRD TIME. THE CAPT TOOK CTL OF THE ACFT. THE TRIMS WERE CHKED A SECOND TIME ALONG WITH THE SPOILER LIGHTS ON THE OVERHEAD PANEL; AGAIN FOUND TO BE NORMALLY POSITIONED. ON THE FOURTH ROLL IT WAS OBSERVED THAT PRIOR TO THE ROLL; THE FLT CTLS BECAME SPONGY AND ROUGH AIR DISTURBANCE COLD BE FELT OVER THE AILERONS. THE ACFT WAS RECOVERED AGAIN AND THE CAPT OBSERVED THAT THERE WAS APPROX 3 INCHES OF ICE AFT OF THE LEADING EDGE BOOTS SPANNING THE ENTIRE LENGTH OF THE WING. THE ICE EXTENDED BACK AS FAR AS COULD BE OBSERVED. THE OUTSIDE TEMP WAS NOTED TO BE INCREASING. AT THIS TIME; PROP RPM WAS INCREASED TO MAX. GEAR WAS EXTENDED AT THE SAME TIME FLAPS WERE EXTENDED TO 15 AND THEN 30 DEGS. THE ACFT WAS STABILIZED FOR A VISUAL APCH AT APPROX 170 KTS. INFLT VISIBILITY WAS APPROX 2 1/2 MI OR BETTER AND THE RWY AND ARPT ENVIRONMENT WERE IN SIGHT. THIS WAS RELATED TO THE TWR AND ACFT WAS MANEUVERED FOR A NORMAL LNDG. ACFT WOULD HANDLE BEST BTWN 180 AND 170 KTS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR EXPLAINED THE REASON FOR USING HIGHER RPM IN ICING CONDITIONS; TO PROVIDE MORE ELECTRICAL PWR TO DE- ICING EQUIP AND ALSO TO PROVIDE SMOOTHER AIRFLOW OVER THE WINGS. HE SAID THE CAPT CAN SEE ALMOST TO THE AFT EDGE OF THE DEICE BOOTS AND COULD SEE THE ICE HAD FORMED ALMOST BACK TO THE 'FAT PART OF THE WING.' HE SAID THIS WAS THE FIRST TIME IN HIS 21 YR CAREER HE HAD FELT THAT HE WAS NOT IN CTL OF THE AIRPLANE. THE WING WOULD DROP; THE NOSE WOULD THEN DROP; AND AS AIRSPD WAS GAINED; THE WING COULD BE RAISED. THEY LOST ABOUT 100 FT EVERY TIME THE WING DROPPED.