Air carrier technicians reported that while replacing an emergency power assist system battery on a B777; the door opened and the escape slide released but did not fully deploy.
Synopsis
Air carrier technicians reported that while replacing an emergency power assist system battery on a B777; the door opened and the escape slide released but did not fully deploy.
Narrative
Was working on Door L1 Emergency Power Assist System (EPAs) battery change. While trying to pin the girt safety release pin under the slide; the door swung open and slide material was released. The slide did not inflate as the cylinder was already pinned.
Second reporter narrative
Unintentional slide release when completing EPAS (Emergency Power Assist System) battery replacement at door L1. EPAS battery arm/disarm lever seemed to be put into the armed position during previous step when removing hinge cover since the motion to take that cover off is to push inboard and aft to clear the hinge arm and down to remove the forward hinge cover; which would be the motion needed to arm the EPAS. In attempt to safety pin the bottle and girt bar; the door was opened and slide released. However; the slide didn't fully deploy because the bottle had the safety pin installed.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.