MECHS INVOLVED WITH SVCING A NOSE LNDG GEAR ON AN EMB145LR (ERJ145LR); ARE INFORMED THE ACFT REQUIRED AN AIR TURN BACK AFTER TKOF. FLT CREW RECEIVED A NOSE GEAR DISAGREE AND TRANSITORY DISAGREE.

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MR X AND I WERE SVCING THE NOSE STRUT. WE LET OUT THE NITROGEN PRE-CHARGE; THEN DRAINED THE HYDRO AND FILLED IT BACK UP. WE DID THIS SEVERAL TIMES THEN TRIED TO CHARGE IT WITH NITROGEN AND IT WOULD NOT TAKE THE FULL CHARGE SO WE CALLED MR Y TO ASSIST US AND HE DID THE WHOLE PROCESS OVER AND SVCED IT TO 7 3--4 IN. THEN SWUNG THE GEAR. THE PLANE TOOK OFF AND THEY GOT A NOSE LNDG GEAR AND TRANSITORY DISAGREE WARNING SO THEY TURNED AROUND AND LANDED. I AM UNSURE OF WHAT WENT WRONG IN THIS EVENT. ALL I WAS TOLD IS THAT IT WAS IMPROPERLY SVCED. SUPPLEMENTAL INFO FROM ACN 783152: MR Z AND I WERE SVCING STRUTS AND WHEN WE CAME TO SVC THE NOSE GEAR STRUT WE COULD NOT GET THE APPROPRIATE AMOUNT OF CHROME TO SHOW. WE THEN CALLED MR Y; ANOTHER MECH TO HELP US OUT. HE CAME OVER AND RELEASED NITROGEN; DRAINED AND SVCED THE STRUT WITH 5606. HE THEN FILLED THE STRUT WITH NITROGEN AND WERE ABLE TO GET THE APPROPRIATE AMOUNT OF CHROME. PLANE HAD AN IN AIR TURN BACK. CREW RECEIVED A NOSE GEAR DISAGREE. NOSE GEAR STRUT WAS RE-SVCED. A MORE EFFECTIVE OPS CHK. WHEN WE SWUNG THE GEAR AND AFTER WE LET THE PLANE BACK ON THE GND; THE NOSE STRUT MAINTAINED THE CORRECT HT. SUPPLEMENTAL INFO FROM ACN 783153: DETECTED AFTER TKOF. STRUT SVCED ACCORDING TO WORK CARDS. HT AND SVC PRESSURE GOOD. LEAK CHK AND GEAR SWINGS GOOD. ACFT TOWED TO THE GATE; NO DETECTION OF LEAK OR LOW STRUT NOTED. ACFT RETURNED TO ZZZ. NOSE STRUT WAS FLAT (NO CHROME SHOWING). RE-SVCED BY CREW AND RETURNED TO SVC. WHY STRUT FAILED AFTER LEAVING THE GATE IS UNKNOWN. SUPPLEMENTAL INFO FROM ACN 783151: WAS TOLD NOSE STRUT WAS FLAT; IMPROPERLY SVCED. REWORK. MAINT WORK CARD AND BREAK UP STEP 1 INTO SEVERAL INDIVIDUAL STEPS; AND MORE -- BETTER OPS CHK.