An Inspector reports about his involvement with the replacement of two cabin door slides on an A319; that were later found with safety pins not removed. Slides at doors 1-Left and 1-Right were inoperative.

Narrative

Aircraft had a deferred item on it for the Emergency Power Supply Unit (EPSU) failed. Troubleshooting determined both door slide assemblies at 1L & 1R were defective. Both slides were simultaneously replaced and inspected per the AMM. The test for the EPSU passed. A few days later the downline OSV reported finding both slides with safety pins installed. Some contributing factors were: Fatigue; due to low manpower. Mechanics possibly relying on Inspector to verify pins removed; and vice-versa. Rush to get plane out of hanger; at end of shift; for departure by management. No job sign-off sheet available for the slide job on this fleet. No mention of a training video available in the maintenance manual (AMM). Slides replaced during an engine order have an auto-generated card issued to instruct supervisor to debrief all parties involved; to make sure key steps were done. This safety net is not set up for non-routine maintenance or deferred items. The safety pins should be designed so that the slide covers (shroud) cannot be installed with pins still in the slide bottle. One write-up used for both slides; leaving room for double failure.Callback conversation with reporter revealed the following information: Reporter stated he was informed the A319 flew three to four days with the cabin door slides inoperative at doors 1-Left and 1-Right. These were slides; not slide/raft combies. He still finds it hard to believe; that he and two other Mechanics; who had taken the turnover from the previous shift; did not see the six inch long cable with the safety pin and additional streamer attached. Reporter believes one possibility could be; if the entire safety pin cable and streamer; were rolled up and stuffed inside and under the slide outer fabric with the pin still installed in the slide bottle valve regulator assembly. Reporter stated he performed the RII inspection and left with only the slide bustle needing to be installed; which was not part of his inspection signoff. The Aircraft Maintenance Manual (AMM) is approximately eighty-two pages long for replacement of these slides. Other types of aircraft in his company's fleet; use a specific document that spells out every step required for slide replacements; but for some reason; his Engineering department has decided not to use the same format for slide replacements on their A319/320's.