WHILE TAXIING OUT; A FLT ATTENDANT CAME RUNNING UP THE AISLE; UNLOCKED THE COCKPIT DOOR; AND SAID THERE WAS A LOUD BOOM IN THE ACFT. AT THE SAME TIME THE INTERPHONE FROM THE AFT CABIN FLT ATTENDANTS ALERTED PLTS THE AFT CABIN WAS FILLING WITH SMOKE AND SUGGESTED EVACING THE ACFT. THE ACFT WAS EVACED IN LESS THAN A MIN AND THE EMER CRASH EQUIP WAS CALLED. APPROPRIATE EMER AND EVAC PROCS WERE ACCOMPLISHED. THERE WAS NO FIRE AND NO ONE WAS INJURED.

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XA25 PUSHED BACK FROM GATE STARTED BOTH ENGS ON PUSHBACK PARKED BRAKES RELEASED GND CREW AND CALLED FOR AND COMPLETED AFTER START CHKLIST. XA30 CALLED FOR AND RECEIVED TAXI INSTRUCTIONS. CHALLENGED FO; CLR ON THE R; HE RESPONDED CLR ON THE R. ADVANCED THROTTLES SLIGHTLY; HEARD WHAT SOUNDED LIKE A MUFFLED EXPLOSION. ACFT SHUDDERED AND FELT PRESSURE IN MY EARS. STOPPED ACFT; LOOKED AT CABIN CTLR AND SAW CABIN RISING; SAW NO LIGHTS ON PNEUMATIC PANEL. FO LOOKED AT EICAS AND SAW NO MESSAGES. NOW THINGS GOT BUSY AND SEVERAL EVENTS OCCURRED AT ONCE. I HEARD RUNNING UP THE AISLE SO UNLOCKED COCKPIT DOOR AND FSM CAME IN AND SAID THERE WAS A LOUD BOOM IN THE ACFT BUT NO FIRE OR SMOKE IN FORWARD CABIN. AT THE SAME TIME THE INTERPHONE SOUNDED FROM THE AFT CABIN; THE FO ANSWERED AND L3 RPTED THAT THE AFT CABIN WAS FILLING WITH SMOKE AND THE PAX WERE IN THE AISLES. FO ASKED; DO WE NEED TO EVAC? L3 RESPONDED YES; SO I DECIDED TO EVAC. I ACTIVATED THE EVAC ALARM AND SHUT DOWN THE ENGS AND MADE AN EASY VICTOR PA WHILE THE FO CALLED FOR THE EMER EQUIP. I CALLED FOR AND EXECUTED THE EVAC CHKLIST. FO WAS FIRST OUT OF THE COCKPIT. I GRABBED MY HAT AND FOLLOWED. WE BOTH SHOVED PAST THE PAX EXITING THE L1 DOOR AND SINCE THE AISLES IN FIRST CLASS WERE BLOCKED; I CLBED OVER THE SEATS. I RAN DOWN THE L AISLE AND FO WENT DOWN THE R SIDE. WE WENT TO THE REAR AND DETERMINED THAT COACH WAS EMPTY; RETURNED TO THE FORWARD AREA WHICH WAS NOW EMPTY EXCEPT FOR THE FSM; AND I THINK 2 FLT ATTENDANTS TOLD THEM TO EXIT. FO RETURNED TO THE COCKPIT SHUT OFF ALARM AND LOOKED AROUND TO SEE IF ANYTHING ELSE SHOULD BE DONE. I WENT BACK TO THE REAR TO INVESTIGATE IF THERE WAS ANY FIRE OR SIGNS OF AN EXPLOSION. I SAW NO EVIDENCE OF FIRE BUT SAW INSULATION AND DEBRIS SPREAD AROUND AFT CABIN; IN PARTICULAR NEAR AFT 3 ROWS ON L SIDE. I ALSO SMELLED WHAT IS BEST DESCRIBED AS AN OVERHEAT SMELL. SAW FO EXIT ACFT FROM R1 AND DETERMINED THERE WAS NOTHING MORE TO BE DONE ON THE ACFT SO I EXITED FROM L1. I HELPED THE FLT ATTENDANTS HERD THE PAX ON THE L SIDE TOWARD THE TERMINAL AND SAW THE FO ROUND UP THE PEOPLE ON THE R SIDE. THE FO TALKED WITH THE POLICE AND I TALKED TO THE FIREMEN AND WE BOTH TOLD THEM THERE WAS NO EVIDENCE OF FIRE ON THE ACFT AT THIS TIME. I WENT INTO THE TERMINAL TO SEE IF I COULD ASSIST THE PAX; SINCE MOST WERE CONCERNED ABOUT THEIR BELONGINGS I WENT BACK TO THE ACFT TO HELP SECURE THEIR BELONGINGS. AS FAR AS I COULD DETERMINE THERE WERE NO INJURIES. I BELIEVE THE PAX (ALL 111) WERE EVACED IN UNDER 1 MIN. THE FSM AND FLT ATTENDANTS WERE PROFESSIONAL AND DID AN OUTSTANDING JOB. THE FO'S PERFORMANCE; ASSISTANCE AND COUNSEL WAS PROFESSIONAL; OUTSTANDING AND INVALUABLE. IT WAS LATER DETERMINED THAT THE BODY DUCT BLEED MANIFOLD RUPTURED AND SPEWED HOT AIR; DIRT; DUST; SMOKE AND DEBRIS INTO THE REAR CABIN THROUGH THE FLOOR GRILLS. WHAT APPEARED TO BE SMOKE WAS PROBABLY A COMBINATION OF CONDENSATION; CAUSED BY THE HOT BLEED AIR HITTING THE COOL CABIN AIR; AND DUST. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THEY WERE IN A B767-200. THE RPTR STATED THERE WAS NO WARNING LIGHT FOR THE BLEED DUCT PROB; BUT THERE SHOULD HAVE BEEN. WHERE THE WELD IN THE BLEED DUCTING BROKE DIRECTED AIR IN SUCH A WAY THROUGH CARGO SIDE WALL GRILLS SO AS TO CAUSE A FOG WHICH LOOKED LIKE SMOKE. ALSO; THE PRESSURIZED AIR BLEW INSULATION FROM THE CARGO COMPARTMENT WALLS THROUGH VENTS AND INTO THE CABIN MUCH LIKE A GARDNER'S LEAF BLOWER. ALSO; TO COMPLICATE THE PROB AND CREATE A PANIC IN THE CABIN WAS THE FACT THE ACFT WAS DESTINED FOR TEL AVIV. THE PAX WERE SPRING LOADED WITH THE IDEA THERE WAS A BOMB ON BOARD. 1 PAX WAS UP IMMEDIATELY YELLING 'BOMB' AND WAS ON HIS WAY UP THE AISLE TO GET TO THE EMER EXIT. THE RPTR STATED THE AIRPLANE WAS ABOUT 10 YRS OLD AND TO HIS KNOWLEDGE THIS HAD NEVER HAPPENED BEFORE. HOWEVER; AS THE AIRPLANES GET OLDER THESE KINDS OF EXPERIENCES MAY BE MORE FREQUENT.