Narrative:

Our flight had the following deferrals. 21-xx-xx; 29-xx-xx-xx; 49-xx-xx. The 29-xx-xx-xx deferral required the adp (air driven pump) to be turned on at certain times. The switch was turned on and we had got the C hydraulic dem pump advisory message and the press light on the hydraulic panel. We called the local maintenance on the radio; and found the air pump circuit breaker (circuit breaker) was out. They advised us to push it in; but it didn't solve the problem; and advised us to come back to the gate. When we returned to the gate the maintenance guys said that [maintenance] was going to defer the whole adp under 29-xx-xx; which knocks out the hmg (hydraulic motor generator). With the APU deferred you can't have the hmg deferred if it's required. The APU was completely fine; but deferred because the adp valve was leaking the bleed air; according to the mechanics. They stated that they have been asking [maintenance] to change the valve for 2 weeks. On our conference with dispatch; [maintenance] and the duty pilot they wound up amending the APU deferral to pneumatics only. So; there wasn't a conflict between the deferrals.once again I believe that this is a case of improper deferrals and undue pressure for crews to take the aircraft to maintain schedule integrity. I understand that the hmg may not have been required per se for our short flight; but when the APU and the adp deferred we were down 2 back up electrical systems and flying through a line of thunderstorms and forecasted lower ceilings. Why would a perfectly good system be deferred just because another system that can be fixed hasn't been? I think we should be erring on the side of safety; and acting out of an abundance of caution in the current climate.

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Original NASA ASRS Text

Title: B767 flight crew reported multiple and conflicting MELs applied to aircraft requiring extensive review and reapplication caused a significant delay in departure.

Narrative: Our flight had the following deferrals. 21-XX-XX; 29-XX-XX-XX; 49-XX-XX. The 29-XX-XX-XX deferral required the ADP (Air Driven Pump) to be turned on at certain times. The switch was turned on and we had got the C HYD DEM PUMP advisory message and the PRESS light on the hydraulic panel. We called the Local Maintenance on the radio; and found the Air Pump CB (Circuit Breaker) was out. They advised us to push it in; but it didn't solve the problem; and advised us to come back to the gate. When we returned to the gate the maintenance guys said that [Maintenance] was going to defer the whole ADP under 29-XX-XX; which knocks out the HMG (Hydraulic Motor Generator). With the APU deferred you can't have the HMG deferred if it's required. The APU was completely fine; but deferred because the ADP valve was leaking the bleed air; according to the mechanics. They stated that they have been asking [Maintenance] to change the valve for 2 weeks. On our conference with Dispatch; [Maintenance] and the duty pilot they wound up amending the APU deferral to pneumatics only. So; there wasn't a conflict between the deferrals.Once again I believe that this is a case of improper deferrals and undue pressure for crews to take the aircraft to maintain schedule integrity. I understand that the HMG may not have been required per se for our short flight; but when the APU and the ADP deferred we were down 2 back up electrical systems and flying through a line of thunderstorms and forecasted lower ceilings. Why would a perfectly good system be deferred just because another system that can be fixed hasn't been? I think we should be erring on the side of safety; and acting out of an abundance of caution in the current climate.

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.