B757-200
Maintenance Airframe; Maintenance Powerplant
Workload; Time Pressure; Confusion; Situational Awareness; Communication Breakdown
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Manuals; MEL; Human Factors; Aircraft; Company Policy
I was working two flights simultaneously. Aircraft Y was a through-flight from ZZZ1 going to ZZZ. Aircraft Y arrived with two discrepancies: 1) Auto Speed Brakes did not deploy on landing; deployed manually. 2) Center (CTR) Autopilot would not engage on departure. I debriefed the flight crew then returned to Aircraft X to take care of a few final items; and transfer the weight cart from Aircraft X to Aircraft Y. I pushed the first aircraft; (Aircraft X); out of the gate which took longer than anticipated due to a 17-minute loading delay; and then returned to Aircraft Y. Due to time constraints; I decided to contact Maintenance Control via cell phone to get MEL control numbers and place both discrepancies on MEL at Aircraft Y rather than returning to the Maintenance office. After discussing the discrepancies with Maintenance Control; it was decided to defer the Auto Speed Brake discrepancy per MEL 27-62-01; and defer the CTR Autopilot per MEL 22-10. Aircraft Y departed 14-minutes late. I later learned that due to the repetitive fault history of the Auto Pilot System on this particular Aircraft Y; that the incorrect MEL reference was used for this deferral. Per the General Maintenance Manual (GMM) process; MEL reference 2X-03-02-C should have been used rather than MEL 22-10-01-A.[Contributing factors] were Human error. Rushing to get both aircraft out on-time. Failing to go back to the Maintenance office and reviewing Aircraft Y's history a second time. This is the first aircraft type that I have worked in my aviation career that is part of the Lower Landing Minimums (LLM) Program. [Recommend that] periodically review GMM manual as a refresher and to note any changes to the reference. Review aircraft histories closer; [in order] to 'flag' any aircraft that have chronic problem histories of systems. Possibly have a system in Maintenance computer that 'flags' aircraft with chronic fault histories on certain systems. Slow down and take the extra time needed to make sure all documentation is correct.
A Line Mechanic working two B757 aircraft simultaneously at departure gates reports deferring a Center (CTR) Auto Pilot System using an incorrect MEL reference. Mechanic later learned one of the B757 aircraft had a history of repetitive faults on the Auto Pilot System requiring a different MEL reference.