A Line Mechanic reports not pulling the L-7 Circuit Breaker (C/B) for the Left engine Electronic Engine Control (EEC) Selector SEC (Secondary) Control Channel; that was part of an MEL 73-21-L Maintenance deferral procedure on a B757-200. An FAA Inspector on a Check ride; noticed the C/B had not been pulled or collared.

Narrative

I was farmed out to a different work area; assigned multiple gates. An air carrier B757-200 flight arrived with a L ENG SEC CONT. STATUS MSG (message). The aircraft also had minor cabin write ups; I also had an arrival on my second gate with assigned work. The L ENG SEC CONT. STATUS MSG was also written up once before in August 2009. Since this item was intermittent; I contacted Line Maintenance Control to discuss and determine a correct course of action to prevent any further revenue flights delays. There was no active STATUS MSG; there was a STATOR VANE MSG on the Engine Propulsion Control System (EPCS) page; captured by the computer as an Auto event. I printed MEL REFERENCE 73-21-L; took paper work out to aircraft; and proceeded to defer the LEFT ENG SEC CONT MSG. Since there was no active message; I misinterpreted MEL 73-21-L step A 4; (IF L ENG SEC CONT IS DISPLAYED; POSITION THE EEC (Electronic Engine Control) MAINTENANCE CHANNEL SELECTOR (SEL) SWITCH ON THE EEC MAINTENANCE PANEL P61 TO AUTO MODE; THEN PULL OPEN AND SAFETY L-7 LEFT EEC CHANNEL SELECT CB (Circuit Breaker) ON P11 (panel); and did not pull L-7 CB. With the lack of manpower and time constraint; I did not consult with any other person. I was notified by my local Union Flight Safety Representative that an FAA Inspector was on a Check ride and discovered EEC CB L-7 not pulled and collared. Factors that lead to the incident were lack of man power; time constraints; and misinterpreting MEL 73-21-L step A.4 Since the incident; I highlight; underline all Maintenance actions. Once all MEL steps are completed; I review all steps a Lead; Maintenance Operations; Maintenance Manager; Line Maintenance Controller to review the MEL and all steps.