Date: 201212
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Light: Night
Aircraft: B757-200
Operator: Air Carrier
Operating under: Part 121
Mission: Cargo / Freight / Delivery
Flight phase: Parked
Second aircraft: B757-200
Aircraft component: Speedbrake/Spoiler
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Technician
Reporter qualification: Maintenance Airframe; Maintenance Powerplant
Human factors: Workload; Time Pressure; Confusion; Situational Awareness; Communication Breakdown
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
When detected: In-flight
Result: General Maintenance Action
Contributing factors: Manuals; MEL; Human Factors; Aircraft; Company Policy
Primary problem: Human Factors

Narrative: 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.




Synopsis: 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.