A320
Maintenance Airframe; Maintenance Powerplant
Distraction; Confusion; Situational Awareness
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Aircraft; Human Factors; Procedure
A320 aircraft right wing overwing slide deployment; February 2013; late morning. Aircraft was in Heavy Maintenance Bay Hangar. While performing Lighting Strike Inspection; was preparing to perform Aircraft Crown Inspection; [but] noted aircraft crown was still wet from snow melting. At that time decided to perform top of Wing Lighting Strike Inspection. [I] entered cabin to gain access to wing top [and fuselage] side surface. At that time I was thinking about completing the right Wing Lighting Strike Inspection before lunch break [approximately thirty minutes away]. I did not consider our safety program that has [another mechanic verify certain procedures are performed by the working mechanic before activating critical equipment or systems; such as overwing slides].  Removed cover from [Overwing] Emergency Exit access handle and pulled handle. Stopped handle movement at sound of overwing slide inflating. After slide deployment; realized did not disarm right overwing emergency slide. [I] called Lead Mechanic and Maintenance Supervisor. [Recommend] having two each placards installed on both sides of 'PULL' handle labeled 'SLIDE' and one placard labeled 'SLIDE' on the interior cover; to alert the mechanic to a caution:  Note: Exit is 'SLIDE' equipped.
Mechanic reports he inadvertently deployed the right wing overwing slide on an A320 aircraft when he pulled the cabin overwing exit handle without disarming the door. He had attempted to gain access to the right wing upper surface for a Lightning Strike Inspection.