A B757-200 FO SUGGESTS THE CARRIER HAVE THE FO'S DOING THE PREFLT WALKAROUND CHK WITH THE ACFT HYD SYS PRESSURIZED. THIS PROC WILL FIND AND CORRECT HYD LEAKS; SUCH AS THE HYD LINE FAULT FOUND ON THE ACFT PRIOR TO FLT.

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DURING WALKAROUND FELT A MOMENTARY BURNING SENSATION IN MY EYES BUT THE PROB DID NOT PERSIST. I HAPPENED TO MAKE SMALL TALK/GREETING WITH A BAGGAGE HANDLER AND IN PASSING HE SAID HE THOUGHT SOMEONE HAD SPILLED SOMETHING ON ANOTHER GATE AND THAT HE HAD HAD THE SAME SENSATION WHEN ACFT HAD PULLED IN ON GATE. I THEN SUSPECTED SOMETHING WITH HIS OBSERVATION AND RETURNED TO THE COCKPIT AND APPLIED HYD PRESSURE TO THE L/CTR AND R SYS AND THEN RETURNED TO MY WALKAROUND. UPON ARR TO THE L WHEELWELL AREA I JUMPED UP ON TOP OF THE MAINS AND WITNESSED A HYD LEAK THAT WAS FOGGING OVER INTO THE WELL AREA. THE HYD LINE IN QUESTION WAS FROM THE L SYS FROM A LINE JUST ABOVE THE FERRULE AT A B-NUT FITTING. THE CRACK IN THE LINE PRODUCED THE FOGGING CONDITION. THE OBSERVATION IS ONE THAT I HAVE HAD SEVERAL TIMES AND I WOULD SUGGEST TO WHOMEVER IT MAY CONCERN THAT WITH OUR AGING FLEET; LESS GND TIMES; FASTER TURNS; ETC; THAT WE MAY NEED TO REVISIT THE PRESSURIZING OF THE FLUID SYS ON OUR ACFT FOR THE PREFLTS TO FIND POTENTIALLY HAZARDOUS OR CATASTROPHIC LINE FAILURES. IT IS HARD TO FIND A LEAK WITHOUT THE LINE PRESSURIZED. IT IS ALSO OBVIOUS THAT THE ACFT PULLED INTO THE GATE WITH THAT CONDITION OR THE HANDLER ON THE GND WOULD NOT HAVE EXPERIENCED WHAT HE IN FACT DID. WITHOUT THE LINE PRESSURIZED THERE WOULD HAVE BEEN NO EVIDENCE OF THE LEAK TO THE CREW THAT ORIGINALLY BROUGHT THE ACFT INBOUND.