Technician reported safety pins were never removed from the escape slides during and after maintenance action. The aircraft operated in revenue service and the pins were removed after a paper work audit discovered the discrepancy.

Narrative

I am writing this statement in the event of Aircraft X; Emergency Escape Slide Pin Removal. Airbus Canada contacted Company to inform them that they had a quality error. They delivered Aircraft X to ZZZ for a prior to service visit with the emergency escape slide pins installed. The aircraft had been flying revenue passengers for approximately a month when they notified the Company. On DATE; I was contacted by my manager stating that I was the last to sign for the door slide pins and I needed to file a Company report. On DATE1 I was notified by Company to complete the report. Here is the timeline. Aircraft X was delivered to ZZZ for prior to service visit followed by a special visit. During the prior to service visit; work instruction cards; Deactivate Escape Sides (RII) and Reactivate Escape Slide (RII) are issued. The main cabin doors are opened and remained open by the use of the slide disarm lever on the interior of the door. Due to no actual maintenance taken place on the doors the door bustles are not removed and the slide pin is not installed. Both task were signed off and the work package was closed. After completion of the prior to service package the aircraft now enters a special visit package to undergo the FDA and 121 inspections. During this visit the aircraft has little to no maintenance and the aircraft is considered under quarantine for the 121 Inspection. The same cards; Deactivate Escape Slides and Reactivate Escape Slides are assigned to this visit. Like the prior to service with no door maintenance task being assigned; the main cabin doors are opened using the slide disarm lever on the interior of the door. The slide bustles were not removed and the pins were not installed per steps 1(X) and 1(Y). Now where I come into this; step 1(X) states to remove the safety pin from the emergency escape slide nitrogen bottle pin hole and put the safety pin in the pocket on the slide. Step 1(Y) states IF REMOVED; install the applicable liner. As the door bustles had not been previously removed I regrettably assumed the slide pins had not been installed or left installed from the manufacture. I did not remove the door bustles and verify that the pin had been removed and I did not reinstall the bustles as the card instructs. I did deviate from the written instruction card task and take fully responsibility for my actions. I apologize for my oversight; and I fully understand the severity this could have. Company Maintenance was notified; and the door slide pins have been removed.