B777-200
Maintenance Powerplant; Maintenance Airframe
Physiological - Other; Confusion
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Environment - Non Weather Related; Human Factors
I was assigned to the tow team as the brakeman. This aircraft was the fifth aircraft moved; and the second B777 of the day. I entered the aircraft through door 2 left; did a walk through to make sure all personnel were off; proceeded to the cockpit and accomplished the ground handling checklist. I confirmed with the tow team that the checklist was accomplished and ready to push. We arrived at [the] hangar and were towed in to parking. After confirming that the chocks were installed from tow team and that the checklist was completed I shut the APU down. Ground power was not available; so the aircraft went dark. I proceeded to 1L door to get off the aircraft. The Arm/Disarm handle appeared to be in the disarmed position (It was dark and handle Silhouette); I opened the door and the door assist bottle activated and slide did also. L1 door area was very dark with no power on the aircraft.
I have been informed that there has been a slide deployment on [the flight I had worked.] The events as I remember them; were as follows. the Captain made a prepare for landing announcement; doors 1 left and 1 right were disarmed by [Flight Attendant XX]; I crossed checked that they were indeed disarmed; Flight Attendant XX made the all call to verify that all doors were disarmed. We waited for the jetbridge to approach [door] 1L. It did not. The Captain then made an announcement saying that the aircraft was not correctly positioned for the jetbridge to approach the aircraft; and that everybody would have to be reseated so that the aircraft could be repositioned. Everybody was reseated; the doors were not rearmed. A tug was attached to the aircraft; and we were then towed maybe 5-6 feet forward. After the aircraft came to a complete stop. Flight Attendant XX was again waiting at door 1L waiting for the jetbridge to approach. The jetbridge approached door 2L instead. The passengers deplaned as usual through the 2L door. Flight Attendant XX and I think two other crew members were the last to leave the aircraft. Frankly I don't know why the slide was deployed because when we left the aircraft; doors 1 left and 1 right were disarmed.
A Flight Attendant reported that the slides on door 1 left and 1 right on the B777 had been disarmed upon arrival. A Maintenance Technician that rode the brakes during the tow from the gate to the hanger mistook the slide has disarmed in the dark cabin and opened the door; deploying the slide.