A B767-300ER WAS DISPATCHED WITH A KNOWN CAPT'S SLIDING WINDOW SEAL AIR LEAK. FLT RETURNED DUE TO LOUD SQUEALING.

Narrative

AUG/FRI/05 ZZZ-ZZZ1 B767ER SHIP X WAS PREPARED FOR AN ETOPS FLT TO ZZZZ. THERE WAS AN INBOUND WRITE-UP FOR THE CAPT'S L-2 SLIDING WINDOW EXPERIENCING A LOUD SQUEAL IN FLT. ON AUG/WED/05 ZZZ1 MAINT CTL INSERTED A MAINT SET-UP TO REPLACE THE SUBJECT SEAL. THE SET-UP WAS NOT PART OF THE WORK PACKAGE ON AUG/FRI/05 BUT WAS LISTED IN THE ONGOING MAINT ITEM LIST. IN AN EFFORT TO REMEDY OR LESSEN THE PROB; I CLEANED THE SEAL FACE; REMOVED DEBRIS FROM THE SEAL AREA; AND REMOVED BLOCKAGE FROM THE WINDOW SEAL LOWER INBOARD AFT VENT HOLES. WHILE THIS TASK TOOK PLACE; CARGO; FUEL; PAX; AND CREW WERE BOARDED. IN THIS CONFIGN; I WAS UNABLE TO PRESSURIZE THE ACFT TO VERIFY CONDITION AND; THEREFORE; BRIEFED THE OUTBOUND FLT CREW. THE CAPT WAS TOLD THAT THE FIX COULD NOT BE VERIFIED IN THE CURRENT CONFIGN; THAT THE WINDOW MAY CONTINUE TO LEAK; AND THAT THE SEAL WAS SET UP FOR REPLACEMENT DUE TO HISTORY. THE ACFT WAS DISPATCHED BUT EXPERIENCED CONTINUED LOUD SQUEALING LEAKAGE OF THE CAPT'S L-2 WINDOW SEAL AND RETURNED TO ZZZ AFTER FLYING OUTBOUND FOR APPROX 2.0 HRS. I RELEASED THE ACFT FOR SVC DUE TO MY BELIEF THAT THE ITEM WAS NOT A SAFETY OF FLT ISSUE. I REACHED THIS DECISION DUE TO A KNOWN HISTORY ITEM BEING ALLOWED TO CONTINUE IN SVC FOR 2-3 DAYS PRIOR TO MY CONTACT WITH THE ISSUE.