Narrative:

After landing on bos runway 4R; tower cleared us to exit l-hand onto diagonal runway 33R; switch to runway 4L tower frequency and monitor; hold short of runway 4L and follow aircraft in front. After exiting we switched frequency and began taxiing toward aircraft in front monitoring crossing instructions being given by 4L tower to aircraft in front. When the copilot began retracting the flaps and ground spoilers; the auxiliary hydraulic pump latched on which is not normal. This caused our attention to be diverted for a moment. I continued following the aircraft ahead when 4L tower controller called our tail number. I immediately brought the aircraft to a stop recognizing I had followed the aircraft in front past the hold short line but still short of the active runway without positive controller confirmation. An aircraft (regional type) was on final for 4L at an approximately altitude of 200 ft AGL. Tower controller after contacting us and our stopping called the aircraft on approach and advised them to go around even though we were short of the active. Tower then cleared us to cross 4L turn l-hand on taxiway north and contact ground control who gave us taxi instruction to the ramp. Supplemental information from acn 698053: as we were rolling toward the MD80; I was running the after landing checklist. We were momentarily distraction during this time by an auxiliary hydraulic pump that activated when the aircraft brakes were applied. The pump reset and remained off when re-armed (it should be off during taxi with the main hydraulic system operating). Before we reached the MD80; it was cleared to cross runway 4L (I did not hear the clearance; but he began to cross before we caught up). We inadvertently followed and our nosewheel crossed the hold short line before tower called and told us to hold our position.

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Original NASA ASRS Text

Title: A GIV CREW DISTR BY A HYD SYS ANOMALY AFTER LNDG AT BOS FAILED TO HOLD SHORT OF AN ACTIVE RWY FORCING LNDG TFC TO GO AROUND.

Narrative: AFTER LNDG ON BOS RWY 4R; TWR CLRED US TO EXIT L-HAND ONTO DIAGONAL RWY 33R; SWITCH TO RWY 4L TWR FREQ AND MONITOR; HOLD SHORT OF RWY 4L AND FOLLOW ACFT IN FRONT. AFTER EXITING WE SWITCHED FREQ AND BEGAN TAXIING TOWARD ACFT IN FRONT MONITORING XING INSTRUCTIONS BEING GIVEN BY 4L TWR TO ACFT IN FRONT. WHEN THE COPLT BEGAN RETRACTING THE FLAPS AND GND SPOILERS; THE AUX HYD PUMP LATCHED ON WHICH IS NOT NORMAL. THIS CAUSED OUR ATTN TO BE DIVERTED FOR A MOMENT. I CONTINUED FOLLOWING THE ACFT AHEAD WHEN 4L TWR CTLR CALLED OUR TAIL NUMBER. I IMMEDIATELY BROUGHT THE ACFT TO A STOP RECOGNIZING I HAD FOLLOWED THE ACFT IN FRONT PAST THE HOLD SHORT LINE BUT STILL SHORT OF THE ACTIVE RWY WITHOUT POSITIVE CTLR CONFIRMATION. AN ACFT (REGIONAL TYPE) WAS ON FINAL FOR 4L AT AN APPROX ALT OF 200 FT AGL. TWR CTLR AFTER CONTACTING US AND OUR STOPPING CALLED THE ACFT ON APCH AND ADVISED THEM TO GO AROUND EVEN THOUGH WE WERE SHORT OF THE ACTIVE. TWR THEN CLRED US TO CROSS 4L TURN L-HAND ON TXWY N AND CONTACT GND CTL WHO GAVE US TAXI INSTRUCTION TO THE RAMP. SUPPLEMENTAL INFO FROM ACN 698053: AS WE WERE ROLLING TOWARD THE MD80; I WAS RUNNING THE AFTER LNDG CHKLIST. WE WERE MOMENTARILY DISTR DURING THIS TIME BY AN AUX HYD PUMP THAT ACTIVATED WHEN THE ACFT BRAKES WERE APPLIED. THE PUMP RESET AND REMAINED OFF WHEN RE-ARMED (IT SHOULD BE OFF DURING TAXI WITH THE MAIN HYD SYS OPERATING). BEFORE WE REACHED THE MD80; IT WAS CLRED TO CROSS RWY 4L (I DID NOT HEAR THE CLRNC; BUT HE BEGAN TO CROSS BEFORE WE CAUGHT UP). WE INADVERTENTLY FOLLOWED AND OUR NOSEWHEEL CROSSED THE HOLD SHORT LINE BEFORE TWR CALLED AND TOLD US TO HOLD OUR POS.

Data retrieved from NASA's ASRS site as of January 2009 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.