FAILURE OF WX RADAR RESULTS IN TURB ENCOUNTER FOR A318.

Narrative

WHILE BEING VECTORED AROUND WX USING WX RADAR TO AVOID CELLS S OF US; OUR WX RADAR FAILED. WE ENCOUNTERED SEVERE TURB APPROX 80-100 MI E OF DEN AT FL390. WE WERE IMC AT THE TIME AND ENCOUNTERED AN AREA OF SEVERE TURB WHICH INCLUDED LIGHTNING; HAIL; ST ELMO'S FIRE AND UNCTLABLE PITCH AND ROLL. AS THE PLT MONITORING; I CONTACTED ARTCC AND TOLD THEM THAT WE HAD LOST OUR WX RADAR AND REQUESTED A HDG AND BLOCK ALT TO EXIT THE CELL ASAP. THE CAPT TURNED THE AUTOPLT OFF; AND BECAUSE THE AUTO THRUST WAS NOT MAINTAINING ADEQUATE AIRSPD; THE CAPT TURNED THE AUTO THRUST OFF. THE JUMPSEATER TURNED ON THE IGNITION (I HAD NOT DONE SO YET). WE MAINTAINED HDG BUT LOST 1000-1500 FT OF ATL. THIS LASTED APPROX 4-5 MINS AFTER WHICH WE WERE ABLE TO REGAIN CTL; ALT AND AIRSPD. TO RESTORE THE WX RADAR; WE TRIED TO RESET IT BY SWITCHING IT OFF; THEN ON. THE RESULT WAS UNSUCCESSFUL. THE CAPT ASKED THE JUMPSEATER TO RESET THE CIRCUIT BREAKER WHICH SUCCESSFULLY RESTORED THE SYS. THE CAPT SPOKE TO THE FLT ATTENDANT AND LEARNED THAT THERE WERE NO INJURIES; BUT SEVERAL UPSET PAX. WHEN IN RANGE; WE REQUESTED THAT MAINT MEET OUR ACFT AT THE GATE.