DURING CLIMBOUT A B757 LOST BLEED AIR FROM THE LEFT ENG. SHORTLY THEREAFTER; THE RIGHT BLEED WAS LOST; RESULTING IN LOSS OF CABIN PRESSURIZATION AND AN EMER DESCENT.

Narrative

WHILE CLIMBING THRU FL240 WITH WING & ENGINE ANTI-ICE ON; WE LOST OUR LEFT BLEED. (LEFT BLEED OFF MESSAGE). WE FOLLOWED QRH PROCEDURE. WE CONTINUED A STEP CLIMB TO FL280; BUT ACFT WOULD ONLY CLIMB AT 500 FPM. AS WE LEVELED AT FL280; WE LOST OUR RIGHT BLEED ALSO. WITH NO BLEED AIR; WE ALSO LOST OUR CABIN PRESSURIZATION. WE PUT ON OUR OXYGEN MASKS; DECLARED AN EMERGENCY; AND BEGAN AN EMERGENCY DESCENT TO 10000 FT. I FLEW THE AIRCRAFT AND COORDINATED A DIVERT INTO ZZZ; WHILE THE CAPTAIN RAN THE CHECKLISTS AND COMMUNICATED WITH OUR FLIGHT ATTENDANTS AND PASSENGERS. HE ALSO MANUALLY ACTIVATED THE PASSENGER OXYGEN SYSTEM. WE DIVERTED AND LANDED AT ZZZ.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE REPORTER STATED THAT MAINT DISCOVERED A FAULTY PNEUMATIC TEMP SENSOR WHICH EVENTUALLY RESULTED IN THE FAILURE AND SUBSEQUENT RUPTURE OF THE PNEUMATIC DUCTING FROM THE LEFT ENG. WHEN BLEED AIR FROM THIS ENG WAS LOST; PROCEDURES WERE FOLLOWED AND THE BLEED ISOLATION VALVE WAS OPENED TO ALLOW BLEED AIR FROM THE RIGHT ENG TO PROVIDE WING ANTI-ICE TO BOTH WINGS. ONE PACK WAS ALSO TURNED OFF AS REQUIRED BY PROCEDURE. BLEED AIR FROM THE RIGHT ENG WAS THEN LOST THROUGH THE FAILED PNEUMATIC DUCTING ON THE LEFT SIDE; AND INSUFFICIENT AIR WAS AVAILABLE TO PRESSURIZE THE ACFT THROUGH THE REMAINING PACK.