Date: 201205
Local time of day: 0001-0600
Location: ZZZZ.ARTCC, FO
Flight conditions: VMC
Light: Daylight
Aircraft: B777 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Cruise
ATC / advisory: Center ZZZZ
Aircraft component: Air Conditioning Distribution System
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Human-Machine Interface
Second reporter function: First Officer; Pilot Flying
Anomaly: Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Maintenance
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: General Maintenance Action
Contributing factors: Human Factors; Aircraft; Procedure
Primary problem: Human Factors

Narrative: In cruise; while checking the status of the EICAS messages; the message MAIN DECK A/C was displayed. After reviewing the QRH; we looked further into the DDPG [Dispatch Deviations Procedures Guide] and discovered that the message was a result of MEL 21-40-01. We looked further into the MEL's and discovered that we were not in compliance due to conflicting MEL's. The MEL's that were on the aircraft and certified as airworthy by Maintenance Control were: 1. MAIN DECK FWD SOV 1 - M21-40-01 2. MAIN DECK FWD SOV 3 - M21-40-013. MAIN DECK AFT SOV 3 - M21-40-011 above has an (O) procedure. #2 & #3 do not have an (O) procedure. Initially; reading only the (O) portion of the MEL's within the DDPG; we were required to position the M/D FLOW switch to HIGH under MEL 21-40-01. The other MEL did not contain an (O) which is an Operational procedure for the flight crew to deal with. When reading all notes it was discovered that there was a conflict with the two MEL's that were placed into the logbook. In order to have FWD SOV 1 MEL'd the AFT SOV 1 and 2 must operate normally. Additionally; the FWD and AFT SOV 3 must operate normally. In order to have the FWD SOV 3 MEL'd; the FWD SOV 1 AND 2 must operate normally. Additionally; the AFT SOV 1 and 2 must operate normally. In order to have the AFT SOV 3 MEL'd; the FWD SOV 1 and 2 must operate normally. Additionally the AFT SOV 1 and 2 must operate normally. As you can see; there is direct conflict within the MEL's and it is not possible to have these respective MEL's active at the same time. The event officially occurred when we blocked out due to NOT being in compliance upon block out. After it was discovered that there was a potential issue with the MEL status of the aircraft; Maintenance Control was consulted. After Maintenance Control agreed that we were out of compliance; we contacted the Chief Pilot to advise him as to the situation. I would like to suggest that a full briefing be at minimum; accomplished by the Maintenance personnel on site to the operating captain/crew prior to every departure. This could possibly assist in all parties being in full understanding of the MEL's and potential conflict between any specific series of MEL's. Furthermore; a more comprehensive check/investigation by Maintenance Control should be conducted before issuing any control numbers for MEL's. It is understood that as Captain; the final responsibility falls upon his/her shoulders as to the airworthiness of the aircraft; however to what extent? Do I need to have them pull every panel and show that each individual item is deactivated; tie wrapped; secured closed or open; etc.; per the MEL? I would hope that once maintenance personnel places MEL's in the logbook; places stickers on the logbook cover; and places stickers on the affected items in the aircraft; then signs off the logbook; that this would mean that the items in the logbook had been checked for compliance; maintenance actions performed; and proper entries made.


Second narrative: As an (O) Operations Procedure; we complied with the statement in the appropriate MEL stating to operate the M/D FLOW switch to HIGH. We as a crew complied with the MEL (O) OPERATIONS function of the respective MELs. The event occurred due to Maintenance improperly certifying an aircraft being airworthy when the respective MEL's were in direct conflict.


Synopsis: B777 flight crew discovers airborne that they have departed with conflicting MEL's concerning Main Deck shut off valves. After consulting with Maintenance the flight continues to destination.