A Lead Mechanic; observing another Mechanic performing aircraft docking safety checks; reports an inadvertent escape slide deployment on an A321 at cabin emergency exit door 3 right (R-3) position; with the door 'Disarmed' and closed. Concerns raised about a design flaw and mechanical failure of the slide inflation bottle regulator valve.
Synopsis
A Lead Mechanic; observing another Mechanic performing aircraft docking safety checks; reports an inadvertent escape slide deployment on an A321 at cabin emergency exit door 3 right (R-3) position; with the door 'Disarmed' and closed. Concerns raised about a design flaw and mechanical failure of the slide inflation bottle regulator valve.
Narrative
An A321 aircraft had just been docked without incident. The Docking and Safety jobcard and associated paperwork were being worked. I am the Lead Technician on said dock. I observed while Mechanic X performed the safety task. The door in question; door 3-right (R-3); was disarmed and the pin engaged and remained closed. From my position; I observed Mechanic X attempt to pin the [slide] reservoir valve. When the pin failed to engage the valve; it was withdrawn. At that instant; the secondary cable fell from the [regulator] valve without being touched. The valve actuated and the slide deployed. The R-3 door remained closed the entire time. Myself; the Lead Mechanic observing and Mechanic X; strictly followed the maintenance guidelines at all times for each and every door on the aircraft. In my opinion; this is a result of a design flaw and a mechanical failure of this series aircraft. In the future I would look forward to working with our air carrier and Airbus to remedy this situation.All the proper paperwork was filled out; all required company actions were taken in accordance with company policies and procedures. The slide and inflation bottle were removed and replaced with serviceable units in accordance with proper Aircraft Maintenance Manual (AMM) procedures. No revenue delays were incurred with this action.
Second reporter narrative
While accomplishing the hangar docking card on an A321 aircraft; I was attempting to install the slide inflation bottle lockout pin without success to fully seat pin into receptacle. I removed [lockout] pin to investigate and the lock cable immediately popped out of the regulator valve on the slide bottle; causing the slide to deploy. Note: the door arming lever was disarmed and door was closed. Door 3-right (R-3) slide deployed; caused by defective slide bottle valve. Replaced slide and bottle per Aircraft Maintenance Manual (AMM). Need to have a better system to indicate when slide bottle valve is in a dangerous condition.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.