Narrative:

Just after starting our descent; I noticed that both main landing gear door lights came on then off; then both main landing gear in transit lights came on then off; then both main landing gear door lights came on then off again. This sequence happened very quickly; as I just happened to be looking at them when it happened. The captain did not see the lights but had heard the noise for the gear cycling. At no time did either of us touch the gear handle. The captain then conferred with maintenance control and conferred with me as to an appropriate course of action. We both agreed that we would perform an alternate gear extension and that we would not declare an emergency unless we got an unsafe indication after we attempted the procedure. Also we agreed that it would be prudent to have emergency services on standby. The captain then contacted ATC with our requests and made announcements to the flight attendants and passenger. We then performed the alternate gear extension procedure and got 3 green lights for the gear and landed without incident. The captain did an excellent job handling the situation with excellent CRM. Callback conversation with reporter revealed the following information: the reporter was unable to provide any additional information concerning the cause of this incident. The flight crew received a late descent clearance and the aircraft was at maximum indicated airspeed in an attempt to get back on profile.

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Original NASA ASRS Text

Title: DHC-8-400 FLT CREW REPORTS UNCOMMANDED RAPID LANDING GEAR CYCLING DURING DESCENT FROM FL240 AT 280 KNOTS. GEAR DOORS NEVER ACTUALLY OPEN.

Narrative: JUST AFTER STARTING OUR DSCNT; I NOTICED THAT BOTH MAIN LNDG GEAR DOOR LIGHTS CAME ON THEN OFF; THEN BOTH MAIN LNDG GEAR IN TRANSIT LIGHTS CAME ON THEN OFF; THEN BOTH MAIN LNDG GEAR DOOR LIGHTS CAME ON THEN OFF AGAIN. THIS SEQUENCE HAPPENED VERY QUICKLY; AS I JUST HAPPENED TO BE LOOKING AT THEM WHEN IT HAPPENED. THE CAPT DID NOT SEE THE LIGHTS BUT HAD HEARD THE NOISE FOR THE GEAR CYCLING. AT NO TIME DID EITHER OF US TOUCH THE GEAR HANDLE. THE CAPT THEN CONFERRED WITH MAINT CTL AND CONFERRED WITH ME AS TO AN APPROPRIATE COURSE OF ACTION. WE BOTH AGREED THAT WE WOULD PERFORM AN ALTERNATE GEAR EXTENSION AND THAT WE WOULD NOT DECLARE AN EMER UNLESS WE GOT AN UNSAFE INDICATION AFTER WE ATTEMPTED THE PROC. ALSO WE AGREED THAT IT WOULD BE PRUDENT TO HAVE EMER SVCS ON STANDBY. THE CAPT THEN CONTACTED ATC WITH OUR REQUESTS AND MADE ANNOUNCEMENTS TO THE FLT ATTENDANTS AND PAX. WE THEN PERFORMED THE ALTERNATE GEAR EXTENSION PROC AND GOT 3 GREEN LIGHTS FOR THE GEAR AND LANDED WITHOUT INCIDENT. THE CAPT DID AN EXCELLENT JOB HANDLING THE SITUATION WITH EXCELLENT CRM. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE REPORTER WAS UNABLE TO PROVIDE ANY ADDITIONAL INFORMATION CONCERNING THE CAUSE OF THIS INCIDENT. THE FLT CREW RECEIVED A LATE DESCENT CLEARANCE AND THE ACFT WAS AT MAXIMUM INDICATED AIRSPEED IN AN ATTEMPT TO GET BACK ON PROFILE.

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.