FALCON 50 CREW LOST CABIN PRESSURIZATION AT FL430; AND DID AN EMER DSCNT TO 10000 FT.

Narrative

WE HAD BEEN CRUISING AT FL430 FOR ABOUT 45 MINS WHEN WE SUDDENLY LOST ACFT PRESSURIZATION. THE CABIN LIGHT AND CABIN HORN CAME ON SIMULTANEOUSLY. I IMMEDIATELY DID AN EMER DSCNT. DURING THE EMER DSCNT I DISCOVERED I COULD NOT TALK TO CTR WITH MY OXYGEN MASK ON. THE FO REALIZED I COULD NOT COMMUNICATE WITH CTR; THEN HE GOT IN TOUCH WITH CTR AND DECLARED AN EMER AS WE WERE DSNDING BELOW FL400. THE FO PROCEEDED WITH THE CHKLIST AS CTR CLRED US DOWN TO 10000 FT. CTR GAVE US VECTORS TO ZZZ WHERE WE MADE AN UNEVENTFUL LNDG. DURING THE EMER DSCNT I NOTICED OUR CABIN PSI HAD DROPPED TO 0 PSI AND OUR CABIN ALT HAD INCREASED TO 14000 FT. WHEN WE NOTICED ALL THE ABOVE WE TRIED TO MANUALLY PRESSURIZE THE AIRPLANE. THE MANUAL PRESSURIZATION MODE DID NOT WORK; MAYBE BECAUSE OUR PWR WAS AT FLT IDLE WHILE DOING THE DSCNT; I DON'T KNOW. I CONTACTED CTR AND TWR AND ASKED IF ANY RPTS NEEDED TO BE FILLED OUT AND BOTH SAID NO. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: MAINT WENT OVER THE ACFT WITH A FINE TOOTH COMB. ALL DOOR SEALS WERE INSPECTED. ALL ELECTRONICS CHKED NORMAL. MAINT REPLACED THE CABIN PRESSURIZATION CTLR; AS A PRECAUTION. NOTHING WAS FOUND POSITIVELY. THE ACFT HAS BEEN RESTR TO OVERLAND RTES. THE ACFT; OVER THE PAST 6 WKS WAS NORMAL.