B767-300 and 300 ER
Maintenance Airframe; Maintenance Powerplant
Communication Breakdown; Confusion; Situational Awareness
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action; General Flight Cancelled / Delayed
Incorrect / Not Installed / Unavailable Part; Human Factors; MEL; Procedure; Staffing; Logbook Entry; Company Policy; Aircraft
I was the person in charge at the Maintenance Control desk; along with new hire Trainee. A B767-300 was en route. Being the only person on duty at the Maintenance Control desk legal to give any maintenance directions; I was involved with all aspects of directions and communications with the entire fleet. During the course of the busy day; B767-300 arrived with inbound issues; including both Emergency Medical Kits (EMK) used; and the left-hand communication radio tuning panel frequency selector control inoperative. Maintenance Line Technician called into Maintenance Control upon [aircraft] arrival and the new hire Trainee answered the phone; and proceeded to work/assist the Line Technician in resolving the issues.Both EMK Kits were deferred with my direction oversight. However; the left-hand audio panel issue was more involved; and required more attention than my tacit; off-handed approval. Unfortunately; my focus on the issue was distracted due to the workload at the Maintenance Control desk. In essence I was working the Maintenance Control desk alone; not being assisted by a wholly qualified Maintenance Controller; a situation which leaves me/anyone; when working with this unqualified Trainee Controller in a rather compromising position. The left-hand audio panel was swapped to the First Officer's position; and that was also deferred with my oversight. Unfortunately there was some ambiguity in the audio panels and MEL reference. Hence due to the difference in audio panels on this aircraft; the incorrect MEL reference; 23-10-01-01 was applied. The aircraft flew one leg and continued to another station. At that station the applied MEL was questioned by the outbound Captain; reviewed by Maintenance Control; and the correct MEL applied; 25-11-02-03 which rendered the First Officer's seat inoperative. The MEL was amended and the correction noted.
A Maintenance Controller describes an understaffed work environment; a distracting heavy workload and ambiguity in the MEL Manual that contributed to an improper MEL deferral of a Captain's left-hand audio panel with the First Officer's audio panel on a B767-300 aircraft.