AN AIRBUS 320 TAXIING ON PACKED SNOW AND ICE EXITED THE TXWY DURING A R ENG PWR RUN-UP. ACFT INCURRED NO DAMAGE.

Narrative

WE WERE CLRED TO TAXI OUT TO RWY 32L; INTXN 10 FOR TKOF. AFTER WE TURNED THE CORNER FROM A7 ONTO TXWY T; I PROCEEDED TO DO AN ENG RUNUP TO 50% N1; AS PER OUR AIRLINE WINTER OPS SOP'S. AS I WAS APPLYING BRAKES WHILE MOVING ON THE TXWY T; I RAN UP THE L ENG AND BACK TO IDLE. THEN I RAN UP THE R ENG; AND AS THE PWR WAS AROUND 50% N1; THE ACFT STARTED TO VEER TO THE L OFF TOWARD THE EDGE OF THE TXWY. IMMEDIATELY; I PULLED THE PWR TO IDLE AND APPLIED MAX BRAKING. THE ACFT'S NOSEWHEEL CAME TO REST ON A HARD SURFACE AREA A LITTLE BIT BEYOND THE TXWY EDGE MARKINGS AND IN THE VICINITY OF THE BLUE TXWY LIGHTS. THE MAIN GEAR WHEELS CAME TO REST WITHIN THE CONFINES OF THE TXWY AND NEVER CROSSED PAST THE TXWY EDGE MARKINGS. MAINT MET THE ACFT AND INSPECTED THE AREA. THERE WAS NO DAMAGE TO THE ACFT OR THE TXWY LIGHTS. A TUG WAS HOOKED UP AND THE ACFT WAS PUSHED ONTO TXWY T. WE THEN TAXIED BACK TO TERMINAL WHERE A FURTHER INSPECTION WAS DONE. A NEW MAINT RELEASE WAS ISSUED REFLECTING THE INSPECTION; AND WE PROCEEDED TO BOS. THE SURFACE CONDITIONS ON TXWY T FROM T7 TO T10 WERE PACKED SNOW AND ICE; AND THERE WAS LIGHT SNOW FALLING AT THE ARPT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE BRAKES WORKED OK. THE PROB WAS THE PACKED ICE AND SNOW AND THE R ENG AT 50% N1 CAUSED THE VEERING TO THE L AND THE EXCURSION FROM THE TXWY. THE RPTR SAID THE ACFT NEVER WAS OFF THE CONCRETE EVEN WITH THE NOSE GEAR SLIGHTLY PAST THE BLUE LIGHTS. THE RPTR STATED THE AIRPLANE WAS INSPECTED AND FOUND OK FOR SVC WITH NO DAMAGE.