Flight Crew Air Transport Pilot (ATP)
Confusion
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Became Reoriented; Flight Crew Overcame Equipment Problem
MEL; Human Factors; Aircraft; Procedure
We inspected the logbook after a lengthy maintenance delay for an unrelated open item. Item 9; dated [two days prior] read 'Offside FM control displayed on left ND and status message AP 1 inop.' The item had been written up at the gate before departure and was deferred by Maintenance with the following entry: 'Checked and appd for deferral. Placarded #1 autopilot inop per MEL.' Aircraft flew 6 times after that write up. The First Officer and I reviewed the Mel 22-01A (as cited in the logbook) and complied with it fully. Shortly after takeoff I realized that both NDs needed to be in the same range to avoid the 'map not available' display on the captain's ND. Further investigation revealed that FMGC 1 position indicated all dashes. We now suspected that the logbook incorrectly addressed an autopilot 1 failure; not a failure of FMGC 1. Thinking that Maintenance misdiagnosed the original problem we called Maintenance Control and discussed the situation. Together we decided to perform an FMGC manual reset. The reset was successful and all systems; including the original AP 1 inop status message operated normally. If in fact if the FMGC was the problem then the aircraft should have only been permitted 3 flights on deferral.
[Report narrative contained no additional information].
A321 flight crew discovered that an MEL issued two days prior for a autopilot #1 failure was actually caused by the failure of the # 1 FMGC. Maintenance is contacted and an FMGC reset procedure is performed successfully returning all systems to full operation.