A C500 CITATION PLT LOSES HIS CABIN PRESSURE DURING A DESCENT IN PROX OF TSTM ACTIVITY NEAR JEF; MO.

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ZKC HAD STARTED MY DESCENT FROM 33000 FT TO 24000 FT. I WAS DEVIATING AROUND SOME TRW CELLS. THERE WAS A LINE OF STRONG RETURNS. ABOUT 27000 FT I GOT AN EMER PRESSURE AN NUNCIATOR. I WAS LOSING THE CAB PRESSURIZATION. I FIRST ASKED FOR LOWER; THEN DONNED MY OXYGEN MASK AND SWITCHED TO THE OXYGEN MIKE. CENTER THEN SWITCHED ME TO ANOTHER FREQ TO ASK FOR LOWER. I TRIED TO DECLARE AN EMER; BUT GOT NO REPLY. I USED MY REGULAR HEADSET MIKE TO FINALLY GET LOWER TO 8000 FT. BUT I HAD ALREADY GONE THROUGH 24000 FT TO 23500 FT. I DID RETURN TO 24000 FT UNTIL I COULD GET A CLRNC DOWN. THE CABIN HAD NOT EXCEED 12000 FT YET; BUT IT WAS CLIMBING . WHEN I GOT A CLRNC TO 8000 FT I PULLED THE POWER BACK AND CAME DOWN PRETTY FAST UNTIL I GOT TO ABOUT 13000 FT. I DID NOT HEAR ANY REPLY FROM CENTER ABOUT MY GOING THRU 24000 FT NOR MY CALL FOR EMER DESCENT. WHEN I GOT TO BELOW 12000 FT I CONTINUED A NORMAL APCH (BC) AND LANDING AT JEF. I WAS ORIGINALLY AT 37000 FT AT 150 MI OUT. CENTER DROPPED ME DOWN TO 33000 FT. MY ORIGINAL PLAN WAS TO STAY AT 37000 FT TILL I WAS OVER/PAST THE LINE OF TRWS. BUT CENTER WOULD NOT LET ME DO THAT. I TOOK SOME REALLY HARD BUMPS DESCENDING AND SOMETHING HAPPENED TO THE PRESSURIZATION TO CAUSE IT TO GO TO EMER PRESS. MY OXYGEN MASK WORKED FINE AND THERE WERE NO FURTHER PROBS. LUCKILY I HAD NO PAX ON BOARD.