Maintenance Airframe; Maintenance Powerplant
Confusion; Situational Awareness
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Chart Or Publication; Company Policy; Human Factors; MEL
Referencing B777 MEL; flight crew stated their Ipad MEL showed MEL 21-55a for the Trim Air Pressure Regulating Shut-off Valve (PSROV). Placard hard-copy printed from Maintenance computer showed MEL 21-48a for Trim Air PSROV.Flight crew noticed the MEL chapter applied in Logbook didn't correlate with their Ipad MEL. Pilot later noticed effective date in their Ipad MEL was for XB-January 2013; today is still XA-January 2013 (the day before). Also; as the MEL chapter for this issue appears to be changing; we might have an MEL conflict tomorrow with currently applied MELs. Clearly MEL should not be used until 'Effective' date; some sort of notice needs to block usage until the actual date. If MEL numbering does change; does the new MEL reflect the possibility that the numbers might not correlate?
Reporter stated he has been told the Master MEL (MMEL) has been revised that should affect all B777 Operators. He is concerned about MELs issued using the old MEL reference numbers for a specific deferral and Maintenance Procedure (M) that now have a different MEL number and possibly different (M) procedure that may be required to be accomplished prior to departure. If Maintenance performs trouble shooting on an overnight B777 that is on day two; of a five day deferral; and the revised MEL is 'Effective' on day three of the old MEL; which MEL is legal. There is no cross reference for Flight crews or Maintenance to see the original MEL and the new MEL that are applicable for the same item being deferred. Maintenance is basically blind to what happened yesterday in regards to cross referencing of the old and revised MMEL when the changes become 'effective'.Reporter stated there are controls in the Ipad ACROBAT program and reader that would not display the revised MMEL until the actual 'Effective date'. His Air Carrier does not believe the issues raised are a high priority; no actions on his suggestions have been noted. Reporter also noted the B777 uses PSROVs in their Air Conditioning System; not just on the aircraft's engines.
A Line Mechanic reports that flight crews are referring to B777 MEL references on their Ipads that are not yet 'Effective' for items deferred by Maintenance. Concerns also rose about different MEL section reference numbers and different Maintenance (M) procedures between the old and revised Master MEL (MMEL).