Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Troubleshooting; Confusion; Communication Breakdown
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Returned To Gate; General Maintenance Action
MEL; Aircraft; Manuals; Procedure
We were assigned Aircraft X. Upon reviewing the maintenance sheet I became confused regarding MEL #XX-XX. The original entry in the logbook and the description on the sheet were not easily understood so I elected to contact maintenance. After having a ten minute conversation with the technician about the complexities of the MEL; we both agreed that we were good to go. However; he stated that he was slightly concerned with the legality of the MEL; would look into it further and contact me before departure (we still had approximately 30 minutes before push) if he determined it was not legal. We did not hear back from him until we had pushed and had begun engine start. At this time; he informed us that it was indeed not a valid MEL. We then returned to the gate and the airplane was taken out of service. To the best of my knowledge; the airplane had flown for four days in this condition. Simplify the wording on the maintenance sheet and have a more direct description of this item in the MEL.
B737-800 Captain reported discussing the validity of an MEL with maintenance resulting in an invalid MEL in the logbooks.