Commercial Fixed Wing
Maintenance Airframe; Maintenance Powerplant
Communication Breakdown; Training / Qualification; Troubleshooting
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Fuel Issue; Inflight Event / Encounter Fuel Issue
General Flight Cancelled / Delayed; General Maintenance Action
Aircraft; Procedure; MEL; Human Factors
While operating Aircraft X ZZZ-ZZZ1; the flight crew noted a fuel imbalance message on the FQIS (Fuel Quantity Indicating System) display. A snapshot was recorded; and 0.0 readings were noted at L/H tank probes #14 and #16. Later; the R/H tank #10 position and L/H tank #12 position reported 0.0; as well. 777/787 Maintenance Control Technician then AOG'd probes to ZZZ1 to repair system prior to flight. Overnight; at some point; Engineering became involved and issued an EA (Engineering Authority) stating a specific MEL to use (which they do not have the authority to do) that was incorrect and bypassed the usage of the correct MEL; which limits the flight to 50 nm of land.Engineering must not be allowed to specify MEL usage in EAs. They do not have the authority nor knowledge to do so. Engineering must not be allowed to circumvent MEL usage causing a safety of flight or Out of Compliance issue.The correct MEL application is MEL 28-XX-Y; which limits the aircraft to within 50 nm of land. This created a major Non-Compliance and Safety of Flight issue.
Technician reported that during preparation for a repair procedure; it was discovered that Engineering had mistakenly applied the wrong MEL and did not have the authority to perform that function. The aircraft flew in service out of compliance for ETOPS.