Narrative:

During climb to FL370 (at approximately.360-365 and prior to engine power reduction) both isolated engine bleed and pack/air conditioning systems failed/tripped off resulting in immediate loss of cabin pressurization. Emergency descent and return to denver initiated. Passenger and crew oxygen masks were required until level at 10000 ft MSL. Although cabin oxygen masks deployed, 11 rows failed to have oxygen generator active trereby leaving some passenger without oxygen (aircraft full--190 passenger) for short remaining duration (1-2 minutes) to 10000 ft MSL. Investigation revealed lanyard pin in oxygen canister failed to dislodge and prevented activation. Cause of engine bleed failure under investigation. No obvious cause was evident to flight crew. Due to passenger oxygen mask deployment (located in bottom of overhead bin) when storage doors hung open it blocks passenger flight attendant call light from view of flight attendants. Those passengers requiring assistance of flight attendant due to oxygen mask failure were unable to be immediately identified. Callback conversation with reporter revealed the following information: the reporter said the right bleed system tripped off first followed by the left bleed system seconds later. The reporter said the isolation valve was closed so the bleeds were operating isolated. The reporter stated that both bleed systems were reset and operational just before reaching 10000 ft. The reporter stated the failure of the passenger oxygen system to 11 rows was the firing pin attached to the release cable was still inserted into the safety pin hole used for shipping the oxygen generator. The reporter said the oxygen module door obstructed the passenger call lights and the flight attendants were unaware of passenger's lack of oxygen. The reporter stated the failure of two simultaneous bleed systems was worked by maintenance and parts were replaced but no positive fault was discovered. The reporter said the aircraft was maintenance ferried to the overhaul base at ZZZ and more work was accomplished but again no positive cause was determined.

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Original NASA ASRS Text

Title: A B757-200 IN CLB AT FL360 DECLARED AN EMERGENCY AND DIVERTED DUE TO LOSS OF CABIN PRESSURE CAUSED BY RIGHT AND LEFT ENGINE BLEED TRIPS.

Narrative: DURING CLIMB TO FL370 (AT APPROX.360-365 AND PRIOR TO ENGINE PWR REDUCTION) BOTH ISOLATED ENGINE BLEED AND PACK/AIR CONDITIONING SYSTEMS FAILED/TRIPPED OFF RESULTING IN IMMEDIATE LOSS OF CABIN PRESSURIZATION. EMERGENCY DESCENT AND RETURN TO DENVER INITIATED. PAX AND CREW OXYGEN MASKS WERE REQUIRED UNTIL LEVEL AT 10000 FT MSL. ALTHOUGH CABIN OXYGEN MASKS DEPLOYED, 11 ROWS FAILED TO HAVE OXYGEN GENERATOR ACTIVE TREREBY LEAVING SOME PAX WITHOUT OXYGEN (ACFT FULL--190 PAX) FOR SHORT REMAINING DURATION (1-2 MINUTES) TO 10000 FT MSL. INVESTIGATION REVEALED LANYARD PIN IN OXYGEN CANISTER FAILED TO DISLODGE AND PREVENTED ACTIVATION. CAUSE OF ENGINE BLEED FAILURE UNDER INVESTIGATION. NO OBVIOUS CAUSE WAS EVIDENT TO FLC. DUE TO PAX OXYGEN MASK DEPLOYMENT (LOCATED IN BOTTOM OF OVERHEAD BIN) WHEN STORAGE DOORS HUNG OPEN IT BLOCKS PAX FLIGHT ATTENDANT CALL LIGHT FROM VIEW OF FLIGHT ATTENDANTS. THOSE PASSENGERS REQUIRING ASSISTANCE OF FLIGHT ATTENDANT DUE TO OXYGEN MASK FAILURE WERE UNABLE TO BE IMMEDIATELY IDENTIFIED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR SAID THE RIGHT BLEED SYSTEM TRIPPED OFF FIRST FOLLOWED BY THE LEFT BLEED SYSTEM SECONDS LATER. THE RPTR SAID THE ISOLATION VALVE WAS CLOSED SO THE BLEEDS WERE OPERATING ISOLATED. THE RPTR STATED THAT BOTH BLEED SYSTEMS WERE RESET AND OPERATIONAL JUST BEFORE REACHING 10000 FT. THE RPTR STATED THE FAILURE OF THE PAX OXYGEN SYSTEM TO 11 ROWS WAS THE FIRING PIN ATTACHED TO THE RELEASE CABLE WAS STILL INSERTED INTO THE SAFETY PIN HOLE USED FOR SHIPPING THE OXYGEN GENERATOR. THE RPTR SAID THE OXYGEN MODULE DOOR OBSTRUCTED THE PAX CALL LIGHTS AND THE FLIGHT ATTENDANTS WERE UNAWARE OF PAX'S LACK OF OXYGEN. THE RPTR STATED THE FAILURE OF TWO SIMULTANEOUS BLEED SYSTEMS WAS WORKED BY MAINT AND PARTS WERE REPLACED BUT NO POSITIVE FAULT WAS DISCOVERED. THE RPTR SAID THE ACFT WAS MAINT FERRIED TO THE OVERHAUL BASE AT ZZZ AND MORE WORK WAS ACCOMPLISHED BUT AGAIN NO POSITIVE CAUSE WAS DETERMINED.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.