A CORPORATE JET'S WX RADAR FAILED INFLT. THE FLC WAS FORCED TO TAKE EVASIVE ACTION AFTER THE ACFT ENCOUNTERED HVY RAIN; SEVERE TURB; HAIL; AND LIGHTNING.

Narrative

WE HAD DEPARTED FXE FOR JAX AT XA30 LCL TIME. OUR RADAR (CL60) IS NORMALLY VERY SENSITIVE AND IT PAINTED SCATTERED LEVEL 2 AND LEVEL 3 CELLS AS WE FLEW NBOUND. OUR RIDE WAS SMOOTH AND WE WERE IN MIXED FLT CONDITIONS. 1/2 WAY TO JAX THE RADAR HAD CLRED UP COMPLETELY. THIS PICTURE FLT WITH OUR PREFLT WX AND OUR RIDE REMAINED SMOOTH AS WE FLEW NBOUND WITH 100 NM RADAR RANGE SELECTED. JUST N OF ORLANDO; DURING A DSCNT TO FL240; WE ENCOUNTERED A MOMENT OF LIGHT RAIN WHICH WE THOUGHT ODD; GIVEN OUR STILL BLANK RADAR SCREEN. JUST A FEW SECONDS LATER; WE FLEW INTO HVY RAIN; SEVERE TURB; HAIL; AND THE ACFT WAS STRUCK BY LIGHTENING. WITHOUT RADAR GUIDANCE I GUESSED THAT A L TURN MIGHT EXTRICATE US FROM OUR PREDICAMENT AND I INITIATED AN ENERGETIC ONE. I ALSO ELECTED TO CONTINUE OUR DSCNT IN HOPE OF ENCOUNTERING IMPROVED CONDITIONS. MY COPLT NOTED THIS VISUALLY (HAIL MADE IT TOO LOUD FOR VERBAL COM) AND THOUGH HE COULD NOT HEAR THE RADIO HE ANNOUNCED OUR CONDITIONS; TURN; AND DSCNT TO THE CTR. JUST THEN; WE FLEW OUT THE SIDE OF THE WX INTO VMC. THE ATC CTLR ISSUED IMMEDIATE CLRNC TO 16000 FT THOUGH WE HAD CALLED AROUND FL238. THE REMAINDER OF OUR FLT WAS FOR THE MOST PART UNEVENTFUL. WE HAD LOST TEMPORARY USE OF OUR YAW DAMPER AND OUR MACH TRIM DUE TO THE LIGHTNING STRIKE. BOTH RESET. OUR OUTER PLYS ON BOTH WINDSCREENS WERE CRACKED AND THE RADOME; LEADING EDGES AND INLETS; WERE ALL DIMPLED OR ERODED. HAPPILY; THERE WERE NO INJURIES AMONG THOSE ABOARD. I DOUBT THAT I'LL EVER REGAIN THE LEVEL OF FAITH I USED TO HAVE IN RADAR. THIS FAILURE WAS INSIDIOUS. WE STILL HAD RANGE ARCS AND NAV DISPLAY AND THEY LULLED ME INTO BELIEF IN AN INOP UNIT. SUPPLEMENTAL INFO FROM ACN 310202: AT ABOUT FL250 WE ENCOUNTERED SEVERE TURB; HVY RAIN AND SEVERE HAIL. MY CAPT; WHILE TRYING TO MAINTAIN CTL; INITIATED A L TURN 90 DEGS AND A DSCNT TO TRY TO GET OUT OF THE WX. I SAW OUR DSCNT THROUGH FL240 AND CALLED JAX STATING 'SEVERE TURB; SEVERE HAIL AND DSNDING.' ZJX IMMEDIATELY CLRED US TO 16000 FT. THE ONLY ACTION I WISH I WOULD HAVE TAKEN WAS TO DECLARE AN EMER. THIS WOULD HAVE HELPED ZJX TO BETTER UNDERSTAND THE SIT. ZJX WAS EXCELLENT IN THEIR ACTIONS. THEY DIDN'T HESITATE TO CLR US LOWER AND HELP US IN ANY WAY POSSIBLE.