Date: 201910
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Aircraft: A320
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Parked
Reporter organization: Air Carrier
Reporter function: First Officer
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Human factors: Workload; Time Pressure; Fatigue; Confusion; Communication Breakdown; Distraction
Second reporter function: Captain
Anomaly: Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
Detector: Person Maintenance
When detected: Aircraft In Service At Gate
Result: General Flight Cancelled / Delayed
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: A Contract Mechanic deployed the L2 slide. When we got to the airplane; mechanics where on board working on an open write up. However; the Captain noticed the mechanic was working on and signed off work performed on the R1 door; even though the write up was for 'R2 door lock indication stuck on unlock.'Once this was brought to his attention he refocused his work to the doors on the aft of the aircraft. While he was waiting for more guidance from Maintenance Control; the mechanic left the aircraft to attend to another issue on another airplane (throughout our interaction he appeared rushed and inattentive to detail and mentioned his workload several times).He eventually returned and went to the aft of the aircraft; and a short time later came to the flight deck to tell us he had inadvertently deployed a slide (L2). He specifically mentioned he was not sure how it happened as the door was disarmed; yet while describing what he did it sounded like he ARMED the door instead of disarming it. After the slide blew the Mechanic left the plane and probably returned 20-25 minutes later and went back to the L2 door with the Station Manager. Shortly thereafter he came to the front of the plane and informed everyone that he had in fact armed the door and blew the slide.Because of the prior confusion of which door needed attention; we had referenced the DOOR page on the flight deck ECAM (Electronic Centralized Aircraft Monitor) several times and; in fact; had the page up at the time of the deployment and we can say no doors on the airplane were armed. It is also worth noting at no point had the inflight team been involved with any actions related to arming or disarming the doors. When we first arrived at the airplane they were asked to wait in the jet bridge while a security sweep was finished; then because of the initial maintenance issues they left to go grab coffee in the terminal. When they returned they sat in first class; which is where they were when the slide blew.


Second narrative: When we arrived at the aircraft; the gate team informed me that the inbound crew had written up a problem with one of the aircraft doors. I spoke with the Contract Maintenance person working on the aircraft and he informed me the previous crew had written up the R2 door lock/unlocked visual indicator and that he had just completed all the checks and that the door operated like it was supposed to but he was pointing to the R1 door. I informed him that he was working on R1 and that R2 was the aft door. He appeared to be flustered and apologized and went to the back of the aircraft to inspect R2 door. A short time later he returned to the flight deck and informed me that the indicator was not working and Maintenance Control was trying to figure out what to do. The Contract Maintenance guy said he didn't have time to wait on them to figure out what do because he had 6 other aircraft waiting on him and that he would be back once Maintenance Control called him with a plan. I started to look through the MEL and logbook and noticed that he had already signed off the door write up as ops check good and that we had a second open write up in the book. I called Maintenance Control and spoke with our mechanic working the issue. I informed him of what was going on and also informed him that the Contract Maintenance guy was in such a rush he wasn't paying attention. I was told they would call him back to the aircraft and that he was the only option for Maintenance. I also called Dispatch to let them know what the status was with the flight and asked to speak to the [Control Center] Operations Manager. I told the [Control Center] Ops Manager what was going on and that I didn't believe this guy was safe. Once Contract Maintenance returned to the aircraft he was visibly frustrated and seemed irritated that he had been called back. I let him know that there was still a second write up that needed to be addressed and he said he would take care of it and went to the back of the aircraft. Next time we saw him he came to the flight deck and informed us that the slide had been deployed and that he didn't know how and insinuated that the Flight Attendant had armed the door while he was gone. NOTE: The flight attendants had not even started their preflight checks and were in the first class section of the aircraft. The First Officer and myself had verified several times that all doors where disarmed with the ECAM (Electronic Centralized Aircraft Monitor) door page. The Contract Mechanic started to explain what he did and said he removed the disarming pin and pushed the disarming lever down and said when he went to open the door the disarmed light illuminated. He had just described the arming and safety alert for slide deployment. He told us he would be back and left the aircraft again. I went back to the back of the aircraft to see what had happened. The L2 door was open and the slide was deployed; I looked at the door and noticed that the arming handle was in the disarmed position and that the safety pin was gone. I asked for the Station Manager to come up to the aircraft and showed her what I had found. The Contract Mechanic came back about this time and started to talk with the Station Manager and I went back to the front to talk with the crew. The Contract Mechanic came up after speaking with the Station Manager and apologized to the whole crew and said it was his fault that the slide deployed. It's also worth noting that the Contract Mechanic refused to take a drug test. The Contract Mechanic was clearly overwhelmed and in too much of a rush. A single mechanic option responsible for multiple airlines is an accident looking for a place to land. Even when there was a safety concern brought up I was told that was our only option. Contract Maintenance is just fine but they need to be dedicated to our aircraft for the time we are on the ground.


Synopsis: A320 Maintenance personnel; Flight Attendant and the Captain reported an inadvertent slide deployment while Maintenance worked on the cabin door.