A B757-200 L DOOR ESCAPE SLIDE WAS REPLACED BUT THE TECHNICIAN FAILED TO REMOVE THE SAFETY PIN FROM THE DOOR ASSIST BOTTLE AND TO CH PRESSURE.

Narrative

ON JUL/MON/04; AT APPROX XA30; ACR ACFT; A B757-200; ARRIVED IN ZZZ. ON A REPOSITION FERRY PERMIT FROM ZZZ1 WITH THE L-4 DOOR SLIDE DEPLOYED AND STOWED IN THE ACFT'S AFT CARGO BIN. THE ORIGINAL LOG PAGE WAS CLOSED FOR A FERRY PERMIT. I OBTAINED A SERVICEABLE DOOR SLIDE; AND PROCEEDED TO INSTALL IT USING BOEING MAINT MANUAL 25-66-01. SINCE THE SLIDE WAS ALREADY REMOVED; I ONLY PRINTED THE INSTALLATION PORTION OF THE MAINT MANUAL. FORGETTING THE B757 HAS A DOOR ASSIST BOTTLE TO HELP WITH SLIDE DEPLOYMENT; I INADVERTENTLY FORGOT TO SVC IT. HAD I PULLED UP THE REMOVAL OF THE SLIDE I WOULD HAVE READ THE FIRST STEPS WERE TO INSTALL SAFETY PINS IN THE SLIDE AND DOOR ASSIST BOTTLE. ALSO I MISSED THE VERY LAST STEP IN THE INSTALLATION PORTION IN RETURNING THE ACFT TO ORIGINAL CONDITION; TO REMOVE THE SAFETY PIN IN THE DOOR ASSIST BOTTLE AND VERIFY PRESSURE. LOG PAGE FOR SLIDE INSTALLATION WAS Y. ON JUL/WED/04; ON A ROUTINE CH THE L4 DOOR ASSIST BOTTLE WAS FOUND EMPTY AND WAS REPLACED IN ZZZ2; LOG PAGE Z. THIS EVENT WAS AN OVERSIGHT ON MY PART. I SHOULD HAVE READ THE MAINT MANUAL MORE CLOSELY.