What was found
(CAN) FOLLOWING AN INSP & SERVICING, A/C WAS GROUND RUN.AFTER 3-4 MINS RT ENGINE WAS BROUGHT OUT OF IDLE & A LOUD BANG WAS HEARD.THE RT ENGINE & NACELLE WAS OBSERVED TO BE ON FIRE: BOTH ENGINES WERE SHUTDOWN & FUEL CUT-OFF CLOSED. ENGINE, TOGETHER WITH A HANGAR FIRE EXTINGUISHER WERE REQD TO EXTINGUISH FIRE: INSP REVEALED DAMAGE TO FIREWALL, TOP OF REAR NACELLE TORN OFF, BOTTOM NACELLE HEAT SHIELD BOWED OUTWARDS, WING ROOT PANEL DEFORMED OUTWARDS & RT GEAR SHOWED SIGNS OF BURNING.INVEST. FOUND FUEL SUPPLY LINE AT BULKHEAD, WHICH HAD JUST BEEN INST, WAS LOOSE.A PRE-RUN LEAK CHECK USING BOOST PUMP PRESSURE HAD NOT REVEALED ANY LEAKS.