B737 Next Generation Undifferentiated
Communication Breakdown; Training / Qualification; Confusion
Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Other / Unknown; Ground Event / Encounter Other / Unknown
General Maintenance Action
Human Factors; Procedure; Manuals; Company Policy
My immediate Supervisor gave me a directive to perform a preflight on the aircraft. [Supervisor] informed me the aircraft had not flown in over a week. Aircraft was out of service for sheet metal repair. I arrived at the aircraft at approximately XA:25 hours. Aircraft was slated for a XB:35 departure. Upon my arrival; the tow team was finishing up securing the aircraft. I met the last tow team man from aircraft on the jetway. I informed him I had the jet and he had nothing to worry about. I proceeded into the cockpit and started my pre departure checklist. Using card 29-XXXX-X-XXXX for reference before flight crew arrived. Tow team was complete with their mission and observed me in the cockpit from the ground. I finished bringing the cockpit to life and proceeded to the rear of the cabin. A few minutes after leaving; for reasons unknown the tow man came back to the cockpit and took it upon himself to deselect the battery off. Disrupting the electrical circuits and instruments on the aircraft. This was the same tow man I had met on jetway minutes before and I informed him I had control of the aircraft.When the company allows unlicensed personal to interfere with maintenance and pilot procedures its a dangerous situation and accident waiting to happen. In this case a unlicensed person failing to listen to the mechanic performing procedures on the aircraft. This person took it upon himself to disrupt the aircraft just 15 minutes before passenger boarding.
Maintenance Technician reported during maintenance preflight a tow crew member went to the cockpit and turned off the battery power without authorization.