What was found
F/A REPORTED A SIREN NOISE AND VIBRATION IN REAR OF A-C. NOTICED AROUND 14,000FT. STOPPED B4 LANDING. SUSPECT LAV-GALLEY EXTRACT FAN. DURING GROUND OPS, LAVATORY VACUUM GENERATOR PRODUCES RUMBLING, EXCESSIVE NOISE AND VIBRATION. NOTED INFORMATION REGARDING LAV-GALLEY EXTRACT FAN DEFFERAL BEING NO HELP. REMOVED AND REPLACED LAVATORY VACUUM GENERATOR. SIREN SOUND IS NORMAL FOR THIS PART. WORKS OK NOW. ALSO REPLACED OUTFLOW VALVE DUE TO REPEAT FAULTS ON CAB PRESS SYSTEM 1.