A B-757-200 CAPTAIN FEELS MAINT TRIED TO GET HIM TO FLY AN ACFT THAT WAS UNSAFE. ISSUE OF DETERMINING HOW MUCH HYD FLUID LEAKING FROM ACTUATOR EXCEEDS LEAK LIMITS.

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FIRST LET ME THANK THE RAMP EMPLOYEE WHO CAUGHT THE LEAK. I AM APPALLED THAT MAINT TRIED TO GET ME TO FLY AN ACFT THAT WAS UNSAFE. AFTER THE L HYD PUMP WAS TURNED ON; THERE WAS A RAPID LEAK FROM THE L WING NOTED BY THE RAMP PERSONNEL. I DID NOT NOTICE ANY LEAKS OR SPILLS DURING MY PREFLT. THE ACFT HAD BEEN SITTING ALL MORNING WITH ALL PUMPS INCLUDING THE ENG HYD PUMPS OFF. MAINT WAS CALLED. THE MECH INFORMED ME THAT THE LEAK WAS WITHIN LIMITS OF X DROPS PER MIN. WHAT I HAVE A GREAT DEAL OF CONCERN IS THE IDEA THAT IF A DOWN LINE STATION WROTE IT OFF; THEN THERE SHOULD BE NO PROB AND THE PLT SHOULD TAKE THE ACFT. THE MECH COUNTED THE DROPS FALLING FROM THE WING NOT FROM THE ACTUAL STREAM OF DROPS COMING OUT OF THE WING (THAT WERE MORE THAN 1 DROP PER SECOND). THE DROPS THAT COUNTED HAD TO FLOW FROM THE OUTBOARD AILERON TO THE FAIRING APPROX 20 FT AWAY AND THEN DROP TO COUNT AS 1 DROP IN TIME. MY POINT IS; THE STREAM OF FLUID COMING FROM THE WING WAS OUT OF LIMITS AND MAINT PROCS SHOULD BE CHKED AS TO HOW TO ACCURATELY DETERMINE AN OUT OF LIMIT CONDITION. SECONDLY; A PLT SHOULD NOT BE PUSHED TO TAKE A FLT.