AN EMB-145 REQUIRED AIR TURN BACK AFTER TWO EACH OUTFLOW VALVES WOULD NOT OPERATE AFTER MAINT WORK. ACFT WOULD NOT PRESSURIZE AFTER TKOF.

Narrative

THERE WAS A MISCOM/MISUNDERSTANDING WHEN MR X TRIED TO ASK ME TO STOW THE HOLD OPEN TOOLS. I MISTAKENLY THOUGHT HE WAS ASKING ME TO CLIP THEM BACK IN THE OUTFLOW VALVES. ALSO; I MISTAKENLY ASSUMED THAT THE REMAINING OPEN MEL MIGHT REQUIRE THE HOLD OPEN TOOLS TO BE INSTALLED IN THE OUTFLOW VALVES. MR X AND MYSELF WERE WORKING TO CLR MEL. BY ABOUT XA00 WE HAD DONE OUR INITIAL PRESSURIZATION TO VERIFY THE LEAK/SQUEAL; AND WE HAD SMOOTHED OUT THE AIRFRAME SEAL AND RE-SECURED IT WITH RTV SEALANT. AT ABOUT XD00 THE RTV HAD SET UP AND WE DID THE FINAL PRESSURIZATION TO VERIFY THAT THE SERVICE DOOR NO LONGER LEAKED/SQUEALED. SO WE WERE READY TO CLEAR THE MEL. AS MR X WAS DOING PAPERWORK; HE INTENDED TO ASK ME TO STOW THE HOLD OPEN TOOLS IN THEIR NORMAL; STOWED POS ON THE L-HAND FADEC RACK. I MISUNDERSTOOD HIM AND THOUGHT HE ASKED ME TO REINSTALL THEM IN THE OUTFLOW VALVES; SO I REINSTALLED THEM IN THE OUTFLOW VALVES. THEN WE CLRED THE MEL. I WAS TOLD THAT THE ACFT TOOK OFF (THE NEXT MORNING) AND SOON THE FLT CREW NOTICED THAT IT WOULD NOT PRESSURIZE. I WAS TOLD THAT FOLLOWING THE RETURN TO FIELD/AIR RETURN; LINE MECHS FOUND THE HOLD OPEN TOOLS INSTALLED IN THE OUTFLOW VALVES; SO THEY REMOVED AND STOWED THE HOLD OPEN TOOLS. THEN THEY OPERATIONALLY CHKED THE ACFT PRESSURIZATION SYS AND RETURNED ACFT TO SVC. MECHS (MYSELF) MUST UNDERSTAND THAT THE ONLY TIME THEY CAN LEAVE THE HOLD OPEN TOOLS INSTALLED IN THE OUTFLOW VALVES IS WHEN THEY ARE CERTAIN THAT AN OPEN MEL REQUIRES THEM TO BE INSTALLED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATES THE TWO EACH OUTFLOW VALVES ARE LOCATED ON THE FWD SIDE OF THE AFT PRESSURE BULKHEAD AND DUMP INTO THE APU COMPARTMENT. THE HOLD OPEN BLOCKS ARE NORMALLY STOWED ON THE L/H FADEC RACK. THE HOLD OPEN BLOCKS ARE USED TO SECURE (LOCK) THE VALVES IN THE OPEN POSITION WHEN THE PRESSURIZATION SYSTEM IS DEFERRED OR WHEN MAINT IS BEING DONE ON OR IN THE AREA OF THE OUTFLOW VALVES.