A B767-300 returned to the foreign departure airport after climb out because the equipment cooling/p...

Narrative:

Maintenance was performed on the equipment cooling system prior to departure. I reentered the cockpit after awakening early from the first break cycle. The cockpit crew was executing the cabin altitude depressurization qrc while starting a descent. After the qrc was complete; I noticed the cabin alt indicating 11;0000' and the cabin altitude alert warning illuminated. An emergency was declared for a rapid descent below 10;000'; and a return to our departure airport. The captain handled ATC; which was challenging with the language difference and the oxygen mask on. The first officer continued flying and landed uneventfully. I as the relief officer handled communications with dispatch via ACARS; the cabin crew; passengers; and backed up the remaining pilots duties and checklist. Fuel dumping was commanded; coordinated with ATC and terminated by 7000'. Cabin advisory declared; emergency equipment requested for possible hot brakes and overweight landing. Aircraft was inspected for overweight landing; a new maintenance release was issued; refiled; refueled; and departed.

Original NASA ASRS Text

Title: A B767-300 returned to the foreign departure airport after climb out because the Equipment Cooling/pressurization System was malfunctioning. The Equipment Cooling System had been MEL'ed prior to departure.

Narrative: Maintenance was performed on the Equipment Cooling system prior to departure. I reentered the cockpit after awakening early from the first break cycle. The Cockpit Crew was executing the Cabin Altitude Depressurization QRC while starting a descent. After the QRC was complete; I noticed the cabin alt indicating 11;0000' and the Cabin Altitude Alert warning illuminated. An emergency was declared for a rapid descent below 10;000'; and a return to our departure airport. The Captain handled ATC; which was challenging with the language difference and the oxygen mask on. The First Officer continued flying and landed uneventfully. I as the Relief Officer handled communications with Dispatch via ACARS; the cabin crew; passengers; and backed up the remaining pilots duties and checklist. Fuel dumping was commanded; coordinated with ATC and terminated by 7000'. Cabin advisory declared; emergency equipment requested for possible hot brakes and overweight landing. Aircraft was inspected for overweight landing; a new maintenance release was issued; refiled; refueled; and departed.

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	855728
Time
Date	200910
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZZ
State Reference	FO
Environment
Light	Night
Aircraft 1
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Pressurization System
Person 1
Function	Pilot Not Flying Relief Pilot
Experience	Flight Crew Last 90 Days 200 Flight Crew Total 10000 Flight Crew Type 4800
Person 2
Function	Dispatcher
Events
Anomaly	Aircraft Equipment Problem Critical

A B767-300 returned to the foreign departure airport after climb out because the equipment cooling/pressurization system was malfunctioning. The equipment cooling system had been MEL'ed prior to departure.