CL60 CREW ENCOUNTERED LARGE HAIL; ICING; AND SEVERE TURB AFTER FLYING INTO A TSTM CELL; WHEN IT WAS NOT DETECTED BY THE ACFT WX RADAR.

Narrative

WE WERE IN IMC IN LIGHT TURB; DSNDING THROUGH ABOUT FL240 FT AT 310 KTS AND 2000 FPM WHEN WE ENCOUNTERED MODERATE TURBULENCE AND MODERATE RIME ICING. AFTER ABOUT 30 SECONDS; THE TURB SUBSIDED; BECOMING LIGHT TURB IN IMC. I RPTED THE INCIDENT TO ATC. WE SCANNED DIFFERENT RANGES AND TILT ON THE RADAR; BUT NOT MORE THAN 30 SECONDS LATER; WE ENCOUNTERED CONTINUOUS SEVERE TURB; MODERATE RIME ICING; AND HEAVY HAIL. THE SECOND VERY VIOLENT INCIDENT LASTED ABOUT 1 MIN. WE BROKE OUT INTO VMC; AT WHICH TIME WE COULD SEE THE AREA OF CUMULONIMBUS CLOUDS WE HAD JUST PENETRATED. NO ONE WAS INJURED. HOWEVER; THE ENTIRE NOSE CONE WAS FRECKLED WITH SPOTS; AND THE TIP OF THE RADOME WAS DAMAGED AND UNSALVAGEABLE. AN AREA OF ABOUT 2 INCHES DIAMETER IN THE COMPOSITE STRUCTURE HAD BEEN SOFTENED BY ALL THE HAIL IMPACT. THERE WERE 2 OR 3 SPOTS OF THE CLR ADHESIVE CAP ON THE RADOME WHERE THE PRECIP PENETRATED AND BLISTERED THE PLASTIC. SOME OF THE SPD TAPE ALONG THE WING LEADING EDGES STRIPPED AWAY. AT THE TIME OF THE ENCOUNTER; THE SAT WAS ABOUT -20 DEGS C. THE LIGHTNING DETECTOR INDICATED A SCATTERED AREA OF ACTIVITY AHEAD OF US. WITHOUT AN ASSOCIATED AREA OF RADAR RETURNS; THE LX DATA IS INCOMPLETE. THE MOST DECEIVING AND DISTURBING FACT WAS THE LACK OF ANY ECHOES; INDICATING AREAS OF PRECIP ON THE RADAR. THE EVENT HAS LEFT ME QUESTIONING THE ACCURACY OF THE WX RADAR SYS. THE ICE DETECTOR SYS GAVE NO INDICATION OF AIRFRAME ICING. IN FACT; THE ACFT HAD A MODERATE ACCUMULATION OF RIME ICE. OUR ONBOARD 'AIRSHOW' SYS WAS INOP; SO WE WERE UNABLE TO UPLINK RADAR INFO FROM A FLORIDA SITE. UPON ARR; THE WSI RADAR FROM DAYTONA BEACH DEPICTED A CLRLY DEFINED GROUP OF CELLS OFF-SHORE. I DO NOT UNDERSTAND HOW WE ENCOUNTERED SUCH VIOLENT WX WITHOUT NOTIFICATION FROM OUR RADAR SYS. WE HAD NO MEANS OF DETECTING CONVECTIVE CLOUDS VISUALLY. WE WERE FULLY RELYING UPON THE TECHNOLOGY IN PLANNING A SMOOTH COURSE. COMPANY AND COLLINS ARE UNABLE TO EXPLAIN WHY RADAR AND ICE DETECTOR SYS DID NOT DEPICT/INDICATE CONDITIONS. SOME THEORIZE THAT WE FLEW UNDER THE ANVIL OF A CB AND ENCOUNTERED HAIL BEING EMITTED FROM THE CELL. THE ONLY LOGICAL EXPLANATION FOR THE ABSENCE OF RADAR ECHOES IS THE POSSIBILITY THAT THE PRECIP AT -80 DEGS C DID NOT PROVIDE GOOD RADAR REFLECTIVITY. I AM NOT CERTAIN OF THIS POSSIBILITY. NOR HAS COLLINS USED THAT AS AN EXPLANATION OF THE INCIDENT.