Narrative:

During climb at approximately FL180; numerous EICAS and system failure messages. Left engine bleed off light on; left pack off light on; and temperature inoperative light on. Referenced QRH procedures and accomplished abnormals. This failure had also occurred on inbound leg reported by previous crew. Maintenance consulted while airborne. The decision was made to return to ZZZ. Emergency declared. Overweight landing procedures and emergency landing procedures accomplished. Landed without incident at ZZZ. Maintenance removed aircraft from service.

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Original NASA ASRS Text

Title: B757-200 EXPERIENCED A FAILURE OF THE LEFT AIR CONDITIONING PACK DURING CLIMBOUT ON ETOPS FLT. FLT CREW DECLARED AN EMER AND RETURNED FOR OVERWEIGHT LNDG.

Narrative: DURING CLB AT APPROX FL180; NUMEROUS EICAS AND SYS FAILURE MESSAGES. L ENG BLEED OFF LIGHT ON; L PACK OFF LIGHT ON; AND TEMP INOP LIGHT ON. REFED QRH PROCS AND ACCOMPLISHED ABNORMALS. THIS FAILURE HAD ALSO OCCURRED ON INBOUND LEG RPTED BY PREVIOUS CREW. MAINT CONSULTED WHILE AIRBORNE. THE DECISION WAS MADE TO RETURN TO ZZZ. EMER DECLARED. OVERWT LNDG PROCS AND EMER LNDG PROCS ACCOMPLISHED. LANDED WITHOUT INCIDENT AT ZZZ. MAINT REMOVED ACFT FROM SVC.

Data retrieved from NASA's ASRS site as of May 2009 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.