AN SF340 FLC HAS TO RETURN LAND WHEN THEIR ACFT'S HYD SYS IS LOST AFTER TKOF FROM DTW; MI.

Narrative

DURING THE INITIAL CLB PHASE OF FLT AFTER TKOF DURING LNDG GEAR RETRACTION; WE RECEIVED A 'MASTER CAUTION' HYDS ON THE CENTRAL WARNING PANEL. WE PERFORMED THE QRH MEMORY ITEMS AND NOTICED THE FOLLOWING CONDITIONS ON THE HYD PANEL: THE MAIN ACCUMULATOR WAS READING ZERO PSI; THE EMER ACCUMULATOR WAS READING BTWN 2500-3000 PSI; THE INBOARD AND OUTBOARD ACCUMULATORS WERE ALSO READING BTWN 2500-3000 PSI WHILE THE HYD QUANTITY WAS READING BTWN 100-150 CUBIC INCHES. WE PERFORMED THE QRH MEMORY ITEMS WHICH LED US TO TURN THE HYD PUMP SWITCH FROM 'AUTO' TO 'OFF;' AND WE PROCEEDED WITH THE REMAINDER OF THE QRH CHKLIST. BASED ON THE INFO WE WERE READING OFF THE HYD PANEL; THIS LED US TO THE PORTION OF THE QRH CHKLIST WHICH READS 'IF EMER PRESSURE NORMAL AND MAIN PRESSURE LOW WITH HYD QUANTITY NORMAL.' WE COMPLETED THIS PORTION OF THE QRH WITH NO CHANGES. THE 'IF MAIN PRESSURE DOES NOT INCREASE; APPLY HYD FLUID LOSS PROC FOR LNDG GEAR; FLAPS AND BRAKE OP; PAGE 08.5' APPLIED TO US AND WE CONTINUED THE QRH CHKLIST. AT THIS POINT; THE HYD QUANTITY GAUGE WAS READING APPROX ZERO. WE CONTINUED WITH THE QRH CHKLIST ON PAGE 08.5 'HYD FLUID LOSS.' OUR SCENARIO WAS NOW THE FOLLOWING CONDITION: 'IF BOTH HYD QUANTITY AND HYD MAIN PRESSURE LOW OR HAND PUMP EXTENSION NOT SUCCESSFUL.' WE PERFORMED THE APPROPRIATE PROCS AND EXTENDED THE LNDG GEAR AS PER FOLLOWS: EMER HANDLE -- PULL; LNDG GEAR HANDLE -- DOWN; BRAKE PRESSURE -- CHK. THIS WAS ALL PROCEEDED BY SLOWING THE ACFT TO THE 200 KIAS AIRSPD LIMITATION AS PER THE QRH. AT THIS POINT; WE COMPLETED THE QRH AND CONTACTED MAINT CTL AND THEN DISPATCH. WE HAD ALREADY NOTIFIED ATC OF OUR DIFFICULTIES AND REQUESTED VECTORS TO RETURN TO DTW. WE ASKED MAINT CTL TO ALSO REVIEW OUR QRH PROCS TO SEE IF THEY HAD ANY ADDITIONAL INPUT FOR US. THE QRH STATEMENT 'IF BOTH HYD QUANTITY AND HYD MAIN PRESSURE LOW OR HAND PUMP EXTENSION NOT SUCCESSFUL' APPLIED TO US AND WE PERFORMED A ZERO FLAP LNDG. DISPATCH CALCULATED OUR LNDG DISTANCE FOR THE CURRENT CONDITIONS AT DTW. AFTER WE TALKED WITH OUR FLT ATTENDANT AND OUR PAX AND HAD COMPLETED OUR CHKLIST ITEMS; WE DECLARED AN EMER AND REQUESTED TO LAND ON RWY 22L AT DTW. WE ADVISED TWR THAT WE WERE PERFORMING A ZERO FLAP LNDG AND THAT WE WOULD HAVE NO NOSEWHEEL STEERING AFTER LNDG. AFTER COMING TO A COMPLETE STOP ON THE RWY AND LNDG WITHOUT INCIDENT; THE ARFF HAD THEIR EQUIP AROUND US WHICH SEEMS TO BE NORMAL PROC. WE WERE ON THE RWY CTRLINE OR EXTREMELY CLOSE TO IT. APPROX 30 SECONDS OR SO AFTER STOPPING; ACFT STARTED TO GENTLY ROLL TOWARD THE E SIDE OF THE RWY TOWARD THE SAFETY AREA. WE IMMEDIATELY ADVISED ARFF TO KINDLY MOVE OUT OF THE WAY ON THE 'COMMON FREQ' AND THEY DID. THE ENGS WERE IMMEDIATELY BROUGHT TO 'FUEL OFF' AND THE PAX WERE ADVISED THAT WE WERE ROLLING INTO THE GRASS AND TO PLEASE STAY SEATED. WE HAD NO NOSEWHEEL STEERING OR BRAKING AUTH AFTER THE ACFT STARTED ROLLING; AND THE ACFT ROLLED VERY SLOWLY AND GENTLY INTO THE GRASS; MAKING CONTACT WITH NO ARPT FEATURES EXCEPT SOME DIRT AND A FEW BLADES OF GRASS. WE BRIEFED THE PAX IN MORE DETAIL AS TO WHAT JUST HAPPENED. THE PAX WERE SOON DEPLANED ONTO A BUS AND TAKEN INTO THE TERMINAL. OUR MECHS THEN SHOWED US THAT THE DOWN LOCK ACTUATOR SWIVEL ON THE R MAIN GEAR HAD BROKEN WHEN THE GEAR WAS RETRACTED. THE ACFT WAS THEN TOWED TO OUR COMPANY FACILITIES.