FLC EXPERIENCES LOSS OF MAIN HYD SYS HYD FLUID.

Narrative

WE DEPARTED INDIANAPOLIS INTL ARPT IN A G159. SHORTLY AFTER LNDG GEAR RETRACTION WE INITIATED FLAP RETRACTION. WE HEARD STRANGE NOISES COMING FROM THE HYD LOCKER LIKE THERE WAS AIR IN THE LINES (SMALL REPETITIVE HAMMERING TYPE SOUND). NEXT; WE FELT A VIBRATION ON THE FLT CTLS. THE VIBRATIONS STOPPED JUST AS THE FLAPS STOPPED AT ABOUT 3-5 DEGS FROM FULL UP. I NOTED THAT NORMAL HYD SYS PRESSURE WAS ZERO AND LEFT MY STATION TO CHK THE FLUID LEVEL (FOUND TO BE EMPTY). I COULD SEE HYD FLUID BLOWING OFF THE TRAILING EDGE OF THE FLAP JUST BEHIND THE L ENG NACELLE. I CAME BACK TO THE COCKPIT TO ADVISE THE FO OF THE SIT AND INCLUDED THE FLT ATTENDANT. AT THIS TIME WE WERE BEING CTLED BY GRISSOM APCH. WE ELECTED TO OVERFLY OKK OUR INTENDED DEST AND CONTINUE ON TO YIP; WHERE WE HAD FACILITIES. WE COMPLETED THE HYD ABNORMALITIES PROC AND CONCLUDED THAT 1) MAIN/NORMAL HYD SYS WAS INOP DUE TO FLUID LOSS (LNDG GEAR; NORMAL FLAPS; NOSEWHEEL STEERING); 2) AUX SYS WAS OK (TOE BRAKES; AND AUX FLAP CTL); 3) THE GEAR WOULD HAVE TO BE EXTENDED WITH THE EMER BLOW-DOWN BOTTLE. WE DECLARED AN EMER ABOUT 25 MINS FROM YIP WITH ZOB. WE ELECTED NOT TO USE THE FLAPS; SUSPECTING THE FLUID LOSS DURING FLAP RETRACTION MAY CAUSE THE AUX SYS FLUID TO BE DUMPED ALSO SHOULD WE TRY TO MOVE THEM. THE FLT ATTENDANT PREPARED THE CABIN AND I GAVE HER THE STANDARD 2 MIN AND 10 SECOND WARNING BEFORE TOUCHDOWN. SHE HAD 1 PAX. A FLAPS UP LNDG WAS MADE AND USED TOE BRAKES TO STEER THE ACFT CLR OF THE RWY AND STOP. WE SHUT DOWN AND HAD IT TOWED TO THE HANGAR. WE ELECTED TO USE YIP OVER PTK (OUR INTENDED FINAL DEST) BECAUSE YIP HAD A LONGER RWY.