Narrative:

Planning our flight we noticed that the aft outflow valve was deferred inoperative. It was a fairly lengthy MEL and one of the notes was that the aft outflow valve was locked in the 7% open position. After discussion and a review of the ditching and emergency evacuation checklists we decided to refuse the aircraft for safety reasons.the ditching checklist requires the crew to manually close both outflow valves (closing holes below the waterline). The emergency evacuation checklist requires the crew to manually open both outflow valves in order to depressurize the aircraft. Obviously; with the aft outflow valve locked in the 7% open position; neither of these checklists could be correctly completed. These checklists are not optional if you end up in either of these situations. The safety implications should be very obvious. It is very concerning to me that we have an MEL that allows an aircraft to be dispatched knowing that we can't complete two emergency checklists if needed. Crews should not be placed in this position.equally disturbing is the fact that after these facts were brought to the attention of the company their response was not to remove the aircraft from service but to find a crew willing to accept this condition. The ultimate irony is that our company has been stressing the dangers of intentional non-compliance recently. Apparently this only applies when it's convenient and won't cause an operational disruption. Dispatching an aircraft after being informed of the inability to perform two emergency checklists is the definition of willful non-compliance.in decades of flying for this company I have never taken a checkride that I was not required to successfully complete an evacuation /evacuation checklist. It seems to me the safety implications in this situation are obvious as is the total disregard for them by our management.

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Original NASA ASRS Text

Title: B777 First Officer and Flight Attendant reported an inoperative outflow valve which prompted the Captain to refuse the aircraft.

Narrative: Planning our flight we noticed that the aft outflow valve was deferred inoperative. It was a fairly lengthy MEL and one of the notes was that the aft outflow valve was locked in the 7% open position. After discussion and a review of the Ditching and Emergency Evacuation checklists we decided to refuse the aircraft for safety reasons.The Ditching Checklist requires the crew to manually close both outflow valves (closing holes below the waterline). The Emergency Evacuation Checklist requires the crew to manually open both outflow valves in order to depressurize the aircraft. Obviously; with the aft outflow valve locked in the 7% open position; neither of these checklists could be correctly completed. These checklists are not optional if you end up in either of these situations. The safety implications should be very obvious. It is very concerning to me that we have an MEL that allows an aircraft to be dispatched knowing that we can't complete two emergency checklists if needed. Crews should not be placed in this position.Equally disturbing is the fact that after these facts were brought to the attention of the company their response was not to remove the aircraft from service but to find a crew willing to accept this condition. The ultimate irony is that our company has been stressing the dangers of intentional non-compliance recently. Apparently this only applies when it's convenient and won't cause an operational disruption. Dispatching an aircraft after being informed of the inability to perform two emergency checklists is the definition of willful non-compliance.In decades of flying for this company I have NEVER taken a checkride that I was not required to successfully complete an evacuation /evacuation checklist. It seems to me the safety implications in this situation are obvious as is the total disregard for them by our management.

Data retrieved from NASA's ASRS site 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.