DASH 8 FLT CREW EXECUTES GAR AFTER NOSE LANDING GEAR INDICATION CYCLES FROM SAFE TO UNSAFE AND BACK TO SAFE AT LOW ALTITUDE. A SAFE LANDING ENSUES USING ALTERNATE GEAR EXTENSION PROCEDURES.

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ON SHORT FINAL; 300-500 FT; VMC APCH WITH ALL LNDG CHKLISTS COMPLETED; THE NOSE GEAR CYCLED FROM A DOWN AND LOCKED CONDITION TO AN UNSAFE CONDITION; ACCOMPANIED WITH A THUMP NORMALLY ASSOCIATED WITH GEAR RETRACTION; AND A SECOND LATER; THE NOSE GEAR WENT BACK TO A SAFE GREEN CONDITION WITH NO YELLOW OR RED. WE MADE THE DECISION TO GO AROUND AND DURING THE EXECUTION OF THE GAR; WE RETRACTED THE GEAR AS PER THE NORMAL GAR PROFILE AND CALLOUTS. WE LEFT THE GEAR UP; AND CONTACTED MAINT; WHO INSTRUCTED US TO EXECUTE THE ALTERNATE GEAR EXTENSION CHKLIST. WE PROCEEDED WITH THE CHKLISTS AND LANDED WITHOUT INCIDENT AND A 3-GREEN INDICATION. AFTER THE FLT; WHILE PLAYING MONDAY MORNING QUARTERBACK FOR OURSELVES; WE REALIZED AND REMEMBERED THE BULLETIN THAT STATES THAT 'USE OF NORMAL HYD GEAR SYS TO EXTEND OR RETRACT THE GEAR MAY EXACERBATE AN UNKNOWN CONDITION.' HOWEVER; IN HINDSIGHT; WE FELT THAT THE APPROPRIATE ACTION WAS TAKEN GIVEN THE LOW ALT GAR MANEUVER. ALSO; WE FOLLOWED THE GAR CALLS AND PROFILE WE HAVE BEEN TRAINED TO DO FOR YRS; AND ROTE MEMORY SEEMED TO TAKE OVER IN THIS TIME CRITICAL EVENT.