Short 330 (N330SB)

registered in Billings MT this is a Short Bros. & Harland Model SD3-30 Registration of this aircraft has the following notation with the FAA Fuel Modifications Modification 1 of 1 11/06/1990 THE AIRCRAFT HAS BEEN FITTED WITH AN AUXILIARY FERRY FUEL SYSTEM TO ENABLE OVERSEAS DELIVERY. THE FUEL TANKS ARE CONSTRUCTED BY PROFAB. INC FROM 1/4 HARD H32 0.05 ALUMINUM. THE PROTOTYPE TANKS WERE TESTED TO 3.5 PSI AND EACH TANK WAS LEAK TESTED TO 2.0 PSI. THE TANKS ARE LOCATED IN THE CABIN ON PLYWOOD FOR EVEN LOAD DISTRIBUTION. THEY ARE SECURED IN PLACE USING CARGO STRAPS AND EXISTING SEAT AND CARGO TIE DOWN POINTS. FUEL IS ROUTED FROM THE TANKS TO THE FERRY FUEL SELECTORS THEN THROUGH FERRY ELECTRIC FUEL PUMPS TO THE FERRY MASTER VALVE, THEN INTRODUCTED TO THE AIRCRAFT FUEL SYSTEM VIA THE AIRCRAFT PRESSURE SUPPLY LINE AS SHOWN ON THE ATTACHED DRAWING