MECH INADVERTENTLY SIGNED OFF 2 SENSE LINES AS HAVING BEEN RECONNECTED DURING AN ENG CHANGE. ACFT WAS FLOWN ON A TRIP WITH BOTH LINES DISCONNECTED.

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I WAS INVOLVED IN AN ENG CHANGE. THE PROCESS I SIGNED DATA CARD OFF FOR 2 SENSE LINES THAT WERE NOT HOOKED UP. THE ACFT LEFT MSP; FLEW TO SAN DIEGO; WHERE THE PROB WAS FOUND AND RESOLVED. I WAS INFORMED OF THE PROB THE NEXT DAY. THE DATA SIGN-OFF I SIGNED WAS FOR A CLAMP I HAD INSTALLED BUT ALSO INCLUDED THE 2 SENSE LINES INVOLVED. ALTHOUGH I DID NOT HOOK UP THE LINES I VISUALLY CHKED THEM AT THE FIREWALL WHICH IS THE NORMAL CONNECTIONS ON AN ENG CHANGE. THEY WERE FOUND DISCONNECTED AT THE VALVE INSTEAD; WHICH I DID NOT CHK. SUPPLEMENTAL INFO FROM ACN 233137: AIR ENG #1 BLEED FAULT. FOUND PNEUMATIC MUSCLE PRESSURE LINE FROM PRV TO TLT AND SENSE LINE FROM UPSTREAM SIDE OF PRV TO TLT BOTH DISCONNECTED. BOTH VALVES OPERATED CORRECTLY AFTER LINES WERE RECONNECTED. FURTHER PROBS OF THIS NATURE CAN BE AVOIDED BY THE USE OF A STEP-BY-STEP CHKLIST OF ITEMS THAT ARE DISCONNECTED DURING ENG REPLACEMENT AND THAT MUST BE RECONNECTED/INSTALLED; WITH INSPECTOR STAMP BLOCKS FOR EACH ITEM. PRESENT PAPERWORK SHOWS ONLY A GENERAL DESCRIPTION FOR INSPECTION SIGN-OFF AND MECH SIGN-OFF.