RPTR THOUGHT THE BRAKES WERE SET BUT WERE NOT. THE RPTR DID NOT ASSURE THE BRAKES WERE SET AND OR THE CHOCKS WERE IN PLACE. THE ACFT ROLLED 4-6 FT INTO THE GPU. THERE WAS A 4 INCH LONG DENT IN THE NOSE CONE.

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I FOLLOWED THE RAMP AGENT'S PARKING INSTRUCTIONS INTO THE GATE AT ICT. RAMP WAS LIGHTED AND TAXI LIGHT WAS OFF. IT WAS A DARK; VFR; WINDY NIGHT. AGENT INSTRUCTED ME TO STOP AND SET PARKING BRAKE. I STOPPED USING TOE BRAKES AND PULLED HANDLE TO SET THE PARKING BRAKE. I DO NOT REMEMBER IF PARKING BRAKE LIGHT ON CREW PANEL CAME ON. #2 ENG WAS ALREADY FEATHERED ON PROP BRAKE. I FEATHERED #1; CALLED FOR PARKING CHKLIST. AGENT HAD GIVEN ME 'SET PARK BRAKE' SIGNAL AFTER HER 'STOP' SIGNAL; BUT SHE DISAPPEARED OUT OF VIEW BEFORE I COULD GIVE HER 'PARKING BRAKE SET' SIGNAL. I NEVER RECEIVED A 'CHOCK IN PLACE' SIGNAL; WHICH IS NOT UNUSUAL. OUR COMPANY REQUIRES IT; BUT A LOT OF TIMES AT JUST ABOUT ALL STATIONS; IT IS NOT GIVEN TO US. ABOUT 30 SECONDS WENT BY WHEN I HEARD A LOUD KNOCKING; CLOSE TO THE DOCUMENT DOOR; AND A YELL. WE WERE STARTLED. BOTH MYSELF AND FO GOT ON TOE BRAKES; OUT OF INSTINCT; AS WE CHKED THE OVERHEAD PANEL AND CAP FOR WARNINGS/CAUTIONS AND OR FAULTS. I ALSO GRABBED THE PARKING BRAKE HANDLE TO CONFIRM ITS POSITION AS THE FO PUSHED THE AUX HYD PUMP BUTTON. WE NEVER FELT THE ACFT MOVE OR STOP AGAIN. I LOOKED OUT THE FRONT WINDSHIELD; BECAUSE WE FELT A SLIGHT VIBRATION AT OUR FEET. WE OBSERVED US TO BE VERY CLOSE TO OR TOUCHING THE GPU. WE INSPECTED THE NOSE CONE AND SAW A 4 INCH LONG DENT IN IT; ABOUT A 1/4 DEEP. FLT ATTENDANT #1 DID NOT FEEL US MOVE OR RESTOP AGAIN EITHER; BUT FLT ATTENDANT #2; WHO STOOD BTWN PROPS IN CABIN; FELT A JERK. SHE DOESN'T KNOW WHAT IT WAS. COULD BE #1 FEATHERING; THE FO AND I THINK. STATION MECH TOLD ME WE ROLLED 4-6 FT. NO CHOCKS IN PLACE.