Narrative:

While working the md-11 desk; I took a call concerning aircraft X. The mechanic said there was an inbound write-up concerning a fuel off schedule alert and tech services wanted to defer tank 1 fuel qty. This peak season I have experienced higher than usual fuel problems with the md-11 while working the md-11 desk; I took a call concerning aircraft X. The mechanic said there was an inbound write-up concerning a fuel off schedule alert and tech services wanted to defer tank 1 fuel qty. This peak season I have experienced higher than usual fuel problems with the md-11 and was happy the mechanic found help elsewhere. Since the aircraft had just arrived and was several hours before departure; I felt it was extreme and suggested other troubleshooting. The mechanic wanted to work as guided and proceed with the deferral. I confirmed the [deferral] procedure and ended the initial call. Review of aircraft X's log showed tank 1 gravity xfer system inoperative and tank unit inoperative in the same tank. My main concern with the qty deferral was focused on requiring the fuel system to operate in manual mode. Pilots prefer systems in automatic and scrutinize mels for conflicts when required to operate in manual mode. Discussion with my partner confirmed the mels do not conflict concerning the requirement for manual mode. I issued deferrals to aircraft X for the #1 fuel tank qty inoperative. The [deferral procedure] is normally completed faster than 3 hours; so I checked the router to see if it was on delay. This is when I found out it was out of service for fuel imbalance. Since the deferrals had been issued; and it was close to departure; I returned aircraft X to service. [The next day] I talked to the crew scheduled to depart aircraft X via VHF. They were on the ground in ZZZ in pre-flight; not yet secured; with a concern of all the tank 1 mels. They pointed out MEL for tank 1 gravity xfer system inoperative under remarks and exceptions line c states the qty must be operative for flight. I immediately realized the conflict and agreed with their concerns aircraft X was not ready for flight in this condition. I then confirmed with flight dispatch that they understood aircraft X was not able to conduct the flight.

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Original NASA ASRS Text

Title: Maintenance Controller reported two deferrals for the MD-11 fuel system were not compatible and the aircraft was removed from service to correct the problem.

Narrative: While working the MD-11 desk; I took a call concerning Aircraft X. The mechanic said there was an inbound write-up concerning a FUEL OFF SCHEDULE alert and Tech Services wanted to defer TANK 1 FUEL QTY. This peak season I have experienced higher than usual fuel problems with the MD-11 While working the MD-11 desk; I took a call concerning Aircraft X. The mechanic said there was an inbound write-up concerning a FUEL OFF SCHEDULE alert and Tech Services wanted to defer TANK 1 FUEL QTY. This peak season I have experienced higher than usual fuel problems with the MD-11 and was happy the mechanic found help elsewhere. Since the aircraft had just arrived and was several hours before departure; I felt it was extreme and suggested other troubleshooting. The mechanic wanted to work as guided and proceed with the deferral. I confirmed the [deferral] procedure and ended the initial call. Review of Aircraft X's Log showed TANK 1 GRAVITY XFER SYS INOP and TANK UNIT INOP in the same tank. My main concern with the QTY deferral was focused on requiring the FUEL SYS to operate in MANUAL mode. Pilots prefer systems in AUTO and scrutinize MELs for conflicts when required to operate in MANUAL mode. Discussion with my partner confirmed the MELS do not conflict concerning the requirement for MANUAL mode. I issued deferrals to Aircraft X for the #1 FUEL TANK QTY INOP. The [deferral procedure] is normally completed faster than 3 hours; so I checked the router to see if it was on delay. This is when I found out it was Out of Service for FUEL IMBALANCE. Since the deferrals had been issued; and it was close to departure; I returned Aircraft X to service. [The next day] I talked to the crew scheduled to depart Aircraft X via VHF. They were on the ground in ZZZ in pre-flight; not yet secured; with a concern of all the TANK 1 MELs. They pointed out MEL for TANK 1 GRAVITY XFER SYS INOP under REMARKS AND EXCEPTIONS line c states the QTY must be operative for flight. I immediately realized the conflict and agreed with their concerns Aircraft X was not ready for flight in this condition. I then confirmed with Flight Dispatch that they understood Aircraft X was not able to conduct the flight.

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.