B757 flight crew reports being dispatched with one engine bleed valve inoperative. At FL340 the left...

Narrative:

While in operations during pre-flight; we received a call from dispatch informing us that there was an MEL that deactivated the right engine bleed valve. Told that we were limited to FL350 or below; and could not be dispatched into known icing. After arriving at the aircraft; we realized that we would have only one pack available for use at a time. At one point in the flight; at FL340; we briefly skimmed the tops of some clouds. The temp was -40. As a precaution I turned on the engine anti-ice. We were past the cloud tops in about 10 seconds. The anti-ice was not turned off after we were past the clouds. Much later at FL340; we noticed pressure changes in our ears. Checked the pressurization panel and noticed that the left engine bleed light was on. The first officer noticed the anti-ice on and turned it off. He recycled the left bleed switch; it did not reset. APU running; we tried to pressurize with it. We were above FL200 and it had some effect and appeared to slow the cabin climb. During all of this we got clearance to FL240 and were descending. I declared an emergency and got clearance to 10;000 ft. The first officer tried switching packs initially; no help. Tried resetting bleed again; no help. As we got lower first officer again switched packs and again reset left bleed and then gained control of pressure. We leveled at 10;000 feet. The cabin got no higher than 9500 feet; no problem with the passengers all very calm. The masks did not deploy. I briefed the flight attendants; did not require a cabin prep. I talked to the passengers and assured them that it was only a pressure problem and that the aircraft was running normal. With control of pressure; dispatch decided to send us to ZZZ for ease of passenger connections. We continued at 10;000 and landed with no further problems.

Original NASA ASRS Text

Title: B757 Flight Crew reports being dispatched with one engine bleed valve inoperative. At FL340 the left engine bleed valve closes automatically and an emergency is declared. Attempts to reset or use APU air are unsuccessful initially and flight descends to 10000 feet and diverts.

Narrative: While in operations during pre-flight; we received a call from Dispatch informing us that there was an MEL that deactivated the right engine bleed valve. Told that we were limited to FL350 or below; and could not be dispatched into known icing. After arriving at the aircraft; we realized that we would have only one pack available for use at a time. At one point in the flight; at FL340; we briefly skimmed the tops of some clouds. The temp was -40. As a precaution I turned on the engine anti-ice. We were past the cloud tops in about 10 seconds. The anti-ice was not turned off after we were past the clouds. Much later at FL340; we noticed pressure changes in our ears. Checked the pressurization panel and noticed that the left engine bleed light was on. The First Officer noticed the anti-ice on and turned it off. He recycled the left bleed switch; it did not reset. APU running; we tried to pressurize with it. We were above FL200 and it had some effect and appeared to slow the cabin climb. During all of this we got clearance to FL240 and were descending. I declared an emergency and got clearance to 10;000 ft. The First Officer tried switching packs initially; no help. Tried resetting bleed again; no help. As we got lower First Officer again switched packs and again reset left bleed and then gained control of pressure. We leveled at 10;000 feet. The cabin got no higher than 9500 feet; no problem with the passengers all very calm. The masks did not deploy. I briefed the Flight Attendants; did not require a cabin prep. I talked to the passengers and assured them that it was only a pressure problem and that the aircraft was running normal. With control of pressure; Dispatch decided to send us to ZZZ for ease of passenger connections. We continued at 10;000 and landed with no further problems.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	893138
Time
Date	201006
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Aircraft 1
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Pneumatic Valve/Bleed Valve
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 90 Flight Crew Total 16000 Flight Crew Type 2000
Person 2
Function	First Officer Pilot Not Flying
Experience	Flight Crew Last 90 Days 55 Flight Crew Total 4389 Flight Crew Type 2290
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural Published Material / Policy

B757 flight crew reports being dispatched with one engine bleed valve inoperative. At FL340 the left engine bleed valve closes automatically and an emergency is declared. Attempts to reset or use APU air are unsuccessful initially and flight descends to 10000 feet and diverts.