CPR JET TAXIES INTO MUD AFTER GOING DOWN POORLY MARKED DEAD-END TXWY AT SYR AND TRIES TO TURN AROUND.

Narrative

AFTER LNDG; TWR CLRED ACFT TO TAXI TO PARKING. TWR WAS WORKING BOTH TWR AND GND CTL. I ENTERED A TXWY THAT WAS NOT NOTAM'ED; MENTIONED ON ATIS OR MENTIONED BY TWR/GND -- AND ONLY AFTER TAXIING SEVERAL HUNDRED FT FOUND BARRICADED CLOSED AT THE ENTRANCE TO FBO RAMP. I ATTEMPTED TO TURN ONTO A SHORT 'STUB' TXWY THAT LED TO A RAMP USED BY ANOTHER FBO. AS I ATTEMPTED TO COMPLETE U-TURN FROM CLOSED TXWY TO STUB TXWY TO RAMP; THE L MAIN LNDG GEAR WENT INTO SOFT TURF BORDERING TXWY. I IMMEDIATELY STOPPED THE ACFT. THE FLT TECHNICIAN AND I GOT OFF THE ACFT TO SURVEY THE SIT. THE ACFT TRAVELED ABOUT 2 FT INTO THE SOFT TURF AND HAD SUNK ABOUT 4-6 INCHES. I RETURNED TO THE COCKPIT AND SHUT DOWN THE ENGS. OUR FBO SENT A TUG OUT TO THE ACFT AND PUSHED US BACK ON THE TXWY; POSITIONING THE ACFT SO IT COULD BE TAXIED WITHOUT FURTHER MANEUVERING. OUR FLT TECHNICIAN; AN A&P/IA INSPECTED THE ACFT PRIOR TO FURTHER FLT. THE WHOLE INCIDENT WAS OVER IN ABOUT 20 MINS. THE TWR COMPLAINED THAT THE CITY HAD CLOSED THE TXWY WITHOUT PROPER NOTIFICATION; HENCE NO NOTAM; ATIS; ETC. THE TWR ALSO MENTIONED THAT SEVERAL OTHER ACFT HAD HAD TROUBLE WITH THE CLOSED TXWY. I DON'T KNOW THE PROTOCOL FOR INFORMING THE FAA ABOUT ARPT INFO; BUT IT SEEMS THE R HAND IS NOT TALKING TO THE L HAND. IF TWR AND GND HAD BEEN OPERATED BY SEPARATE PEOPLE; THERE MIGHT HAVE BEEN TIME TO ALERT US.