Narrative:

On short final; 300-500 ft; VMC approach with all landing checklists 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 go around; we retracted the gear as per the normal go around profile and callouts. We left the gear up; and contacted maintenance; who instructed us to execute the alternate gear extension checklist. We proceeded with the checklists and landed without incident and a 3-GREEN indication. After the flight; while playing monday morning quarterback for ourselves; we realized and remembered the bulletin that states that 'use of normal hydraulic gear system 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 altitude go around maneuver. Also; we followed the go around calls and profile we have been trained to do for yrs; and rote memory seemed to take over in this time critical event.

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Original NASA ASRS Text

Title: 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.

Narrative: 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.

Data retrieved from NASA's ASRS site as of May 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.