A BEECH 1900D WAS DISPATCHED IN NON COMPLIANCE WITH THE R WING OUTBOARD FUEL TANK CAP NOT SECURED RESULTING IN LOSS OF THE CAP INFLT.

Narrative

UPON ARR AT BURLINGTON ARPT; AFTER ACFT WAS PARKED; FUEL TRUCK PULLED UP AND BEGAN FUELING THE R OUTBOARD WING TANK. I TOLD HIM TO STOP FUELING UNTIL I COULD CONFIRM NEEDED FUEL WITH OPS/DISPATCH. I WAS INFORMED BY OPS THAT THIS FUEL TRUCK WAS AT THE WRONG ACFT AND SHOULD BE FUELING ANOTHER COMPANY ACFT THAT WAS JUST BEING PARKED. I INFORMED THE FUELER; WHO CLBED THE LADDER NEXT TO THE WING; OF HIS ERROR AND CONTINUED MY WALKAROUND PREFLT FOR THE NEXT LEG OF THE FLT TO PLATTSBURGH; NY. AFTER START-UP AND TAXI OUT TO THE RWY WITH ALL CHKLISTS COMPLETED; WE TOOK OFF AND LANDED IN PLATTSBURGH NORMALLY. AT THAT TIME A COMPANY EMPLOYEE PAX ON THE ACFT INFORMED ME THAT HE SAW THE LATCH ON THE CAP 'UP' ON TKOF ROLL AND THAT IT WAS MISSING ON LNDG. PART OF THE TKOF CHKLIST CALLS FOR CAPT AND FO TO CHK THEIR RESPECTIVE SIDES FOR THE SECURITY OF THE FUEL CAPS. SUSPECT THAT AS I CONTINUED MY WALKAROUND; FUELER DID NOT SECURE CAP AND THAT DURING TKOF CHKLIST; FO FAILED TO VISUALLY CHK THE FUEL CAP SECURITY PROPERLY. CAP DEPARTED ACFT SOMEWHERE BTWN BURLINGTON AND PLATTSBURGH.