B777-300 flight crew reported pressurization failure resulted in an expeditious return to departure airport.
Synopsis
B777-300 flight crew reported pressurization failure resulted in an expeditious return to departure airport.
Narrative
On climb out the aircraft failed to pressurize. We leveled off and ran the required normal and non-normal checklists. We contacted dispatch; tech support; and the fleet chief pilot. After consultation we decided to return to ZZZ and perform and overweight landing . We performed the overweight landing checklist and Advised ATC as required in the FOM. The first officer performed a text book overweight landing and rolled out to the end of the runway as per the overweight landing notes. The brake temperatures were all normal and the rescue chief stated that everything looks normal. We proceeded to the gate and entered the pressurization and overweight landing into the AML (Aircraft Maintenance Logbook).Cause: We had an MEL item that required the Forward Outflow valve to be locked into the 7% open position. With the forward outflow valve is deactivated there is no indication of on the flight deck of the valve position. It would be helpful if somewhere in our training we could be provided with a picture of what the valve looks like in the position. Then perhaps this entire event could have been avoided during our preflight.
Second reporter narrative
Aircraft failed to pressurize after takeoff; requiring an overweight return to departure field of ZZZ.Cause: Major factor causing the event was the improper positioning of the fwd outflow valve that was under an MEL placard.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.