A B727-200 WAS DISPATCHED IN NON COMPLIANCE WITH A LAVATORY SINK LEAK NOT ENTERED IN THE LOGBOOK OR DEFERRED.

Narrative

WHILE OPERATING AS ACR FLT ABCD FROM ZZZ TO XXX ON APR/XA/01; UPON COMPLETING OUR PREFLT DUTIES; A WATER LEAK WAS DETECTED AROUND THE FAUCET IN THE FORWARD LAVATORY. TRYING TO ISOLATE THE LEAK; THE FE INADVERTENTLY OPENED THE DRAIN VALVE. THE GND CREW ADVISED US OF DRAINING WATER. AFTER RESEARCH AND CONSULTATION WITH OUR MAINT COORDINATOR; THE DRAIN WAS CLOSED AND THE SUPPLY LINE VALVE UNDER THE SINK WAS CLOSED. THE LEAK STOPPED. THE FE ADVISED THE CAPT AND I THAT THE LEAK WAS A NON-AIRWORTHY ITEM THAT COULD BE FLC PLACARDED AND CALLED INTO MAINT CTL ENRTE TO XXX. UPON ARR IN XXX; THE SUPPLY LINE VALVE WAS CYCLED BY THE CREW AND THE LEAK HAD SEATED ITSELF. NO LOGBOOK ENTRY WAS EVER MADE. DAYS LATER; AFTER AN INQUIRY BY THE CHIEF PLT TO KNOW THE REASON FOR OUR DELAY; INVESTIGATION REVEALED IT COULD HAVE BEEN DETERMINED THAT THE LEAK WAS AN ITEM IN THE MAINT DEFERRAL MANUAL AND SHOULD HAVE BEEN AN AIRWORTHY WRITE-UP; POTABLE WATER SYS SECURED BY LCL MAINT AND DISPATCH APPROVAL REQUIRED. CONTRIBUTING TO THE ERROR WAS THE FACT THAT THE FE; ALTHOUGH RELATIVELY NEW; WAS VERY CONVINCING TO BE CORRECT IN HIS INTERP OF THE SIT BUT SHOULD HAVE BEEN QUESTIONED BY EITHER THE CAPT OR MYSELF. I FEEL IT WAS A CRM BREAK. ALTHOUGH A NEW PLT SHOULD BE TRUSTED; HE SHOULD ALSO BE CLOSELY XCHKED BY THE REST OF THE CREW. I FEEL I MAY HAVE GOTTEN A FALSE SENSE OF SECURITY THAT THINGS WERE BEING DONE CORRECTLY BY THE FACT THAT THE CAPT; HAD CONSULTED WITH MAINT.