Narrative:

About 30 seconds to 1 min after gear was selected down, we had a complete loss of system 'a' hydraulic. This occurred between 1600-1800 ft MSL, on about a 5 mi final to runway 27 in bos. The first officer was PF, and I was the PNF. I declared an emergency, told the tower the nature of the emergency, and we then executed a missed approach. We were handed back to bos approach control and I informed them that I would need about 5 mins to complete checklists, before returning to bos for landing. I then informed the passenger, flight attendants on the situation and reason for the go around. I said that after I run some checklists, which would take about 5 mins or so, I would get back to them and let them know what would happen next. Ran the loss of system a hydraulic checklist in the QRH. Gear was already down, and flaps were at 5 degrees. I informed the company via radio the nature of the emergency, and to inform operations. Requested radar vectors to runway 22L. I made a PA to the passenger again, letting them know we were all set up to return to the field for landing. I said everything about this approach and landing should feel normal to them. The only difference is that after landing, we will be stopping on the runway to await a tow truck (tug) to take us to the gate. I also mentioned that emergency vehicles would be on the ground on my request, just for additional safety. I informed the flight attendants that everything was good, and the landing should be a non event, landing in about 5-7 mins. Was turned on about 15-18 mi final to intercept runway 22L. VMC conditions. Radar vectors at 3000 ft MSL the entire event. The runway was 10000 ft in length, and after landing we allowed the aircraft to roll toward the end of the runway for the full stop. Set brakes, and shut down the engines (APU on line). Emergency crews inspected the aircraft, said there was a little smoke coming from the right main gear, but after a closer look, said it was from hydraulic fluid dripping on the brake area, and there was no problem. Maintenance showed up and pinned the gear and towed us to gate X in bos. Were met by station personnel, offered any assistance, I then went to call operations with a report.

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Original NASA ASRS Text

Title: AN ACR CAPT, PNF, DECLARED AN EMER AFTER THE COMPLETE LOSS OF HYD SYS A DURING APCH TO BOS.

Narrative: ABOUT 30 SECONDS TO 1 MIN AFTER GEAR WAS SELECTED DOWN, WE HAD A COMPLETE LOSS OF SYS 'A' HYD. THIS OCCURRED BTWN 1600-1800 FT MSL, ON ABOUT A 5 MI FINAL TO RWY 27 IN BOS. THE FO WAS PF, AND I WAS THE PNF. I DECLARED AN EMER, TOLD THE TWR THE NATURE OF THE EMER, AND WE THEN EXECUTED A MISSED APCH. WE WERE HANDED BACK TO BOS APCH CTL AND I INFORMED THEM THAT I WOULD NEED ABOUT 5 MINS TO COMPLETE CHKLISTS, BEFORE RETURNING TO BOS FOR LNDG. I THEN INFORMED THE PAX, FLT ATTENDANTS ON THE SIT AND REASON FOR THE GAR. I SAID THAT AFTER I RUN SOME CHKLISTS, WHICH WOULD TAKE ABOUT 5 MINS OR SO, I WOULD GET BACK TO THEM AND LET THEM KNOW WHAT WOULD HAPPEN NEXT. RAN THE LOSS OF SYS A HYD CHKLIST IN THE QRH. GEAR WAS ALREADY DOWN, AND FLAPS WERE AT 5 DEGS. I INFORMED THE COMPANY VIA RADIO THE NATURE OF THE EMER, AND TO INFORM OPS. REQUESTED RADAR VECTORS TO RWY 22L. I MADE A PA TO THE PAX AGAIN, LETTING THEM KNOW WE WERE ALL SET UP TO RETURN TO THE FIELD FOR LNDG. I SAID EVERYTHING ABOUT THIS APCH AND LNDG SHOULD FEEL NORMAL TO THEM. THE ONLY DIFFERENCE IS THAT AFTER LNDG, WE WILL BE STOPPING ON THE RWY TO AWAIT A TOW TRUCK (TUG) TO TAKE US TO THE GATE. I ALSO MENTIONED THAT EMER VEHICLES WOULD BE ON THE GND ON MY REQUEST, JUST FOR ADDITIONAL SAFETY. I INFORMED THE FLT ATTENDANTS THAT EVERYTHING WAS GOOD, AND THE LNDG SHOULD BE A NON EVENT, LNDG IN ABOUT 5-7 MINS. WAS TURNED ON ABOUT 15-18 MI FINAL TO INTERCEPT RWY 22L. VMC CONDITIONS. RADAR VECTORS AT 3000 FT MSL THE ENTIRE EVENT. THE RWY WAS 10000 FT IN LENGTH, AND AFTER LNDG WE ALLOWED THE ACFT TO ROLL TOWARD THE END OF THE RWY FOR THE FULL STOP. SET BRAKES, AND SHUT DOWN THE ENGS (APU ON LINE). EMER CREWS INSPECTED THE ACFT, SAID THERE WAS A LITTLE SMOKE COMING FROM THE R MAIN GEAR, BUT AFTER A CLOSER LOOK, SAID IT WAS FROM HYD FLUID DRIPPING ON THE BRAKE AREA, AND THERE WAS NO PROB. MAINT SHOWED UP AND PINNED THE GEAR AND TOWED US TO GATE X IN BOS. WERE MET BY STATION PERSONNEL, OFFERED ANY ASSISTANCE, I THEN WENT TO CALL OPS WITH A RPT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.