Narrative:

Captain reported during normal landing gear extension that nose landing gear indication showed red light with handle in the down position. Crew performed go around and followed the QRH. Did manual extension. Maintenance found grease caked around lock sensor. Removed grease and performed sensor check. Reviewed amm nose landing gear system adjustment and test and rii requirement.callback conversation with reporter revealed the following information: reporter stated he was the maintenance controller on duty when the B737-500 arrived with the nose landing gear indication problem. Reporter stated the flight crew performed a go-around and raised the gear back up after not getting the green light on the initial extension. Apparently the nose gear view port window was obscured and the flight crew could not verify the gear was down and locked; even after the manual extension. After arrival; one of their technicians informed him there was a clump of old; dried; caked grease on and around the lock sensor and target. Technician believed the caked grease had caused movement of the lock sensor; contributing to the lack of nose gear lock indication. A sensor to target gap check was accomplished. This event was considered an indication problem; not a manual extension problem; so the aircraft was released without an rii inspection per the aircraft maintenance manual and their rii list. Since the incident however; his carrier has added the manual extension system to their required inspection item (rii) list whenever the manual extension is used.

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Original NASA ASRS Text

Title: A B737-500 PILOT REPORTED THAT; DURING NORMAL LNDG GEAR EXTENSION THE NOSE LNDG GEAR INDICATION SHOWED A RED LIGHT WITH THE GEAR HANDLE IN THE DOWN POSITION. MAINTENANCE FOUND GREASE CAKED AROUND THE NOSE GEAR LOCK SENSOR. AIRCRAFT WAS RELEASED WITHOUT AN RII INSPECTION.

Narrative: CAPT RPTED DURING NORMAL LNDG GEAR EXTENSION THAT NOSE LNDG GEAR INDICATION SHOWED RED LIGHT WITH HANDLE IN THE DOWN POSITION. CREW PERFORMED GAR AND FOLLOWED THE QRH. DID MANUAL EXTENSION. MAINT FOUND GREASE CAKED AROUND LOCK SENSOR. REMOVED GREASE AND PERFORMED SENSOR CHECK. REVIEWED AMM NOSE LNDG GEAR SYSTEM ADJUSTMENT AND TEST AND RII REQUIREMENT.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED HE WAS THE MAINTENANCE CONTROLLER ON DUTY WHEN THE B737-500 ARRIVED WITH THE NOSE LANDING GEAR INDICATION PROBLEM. REPORTER STATED THE FLIGHT CREW PERFORMED A GO-AROUND AND RAISED THE GEAR BACK UP AFTER NOT GETTING THE GREEN LIGHT ON THE INITIAL EXTENSION. APPARENTLY THE NOSE GEAR VIEW PORT WINDOW WAS OBSCURED AND THE FLIGHT CREW COULD NOT VERIFY THE GEAR WAS DOWN AND LOCKED; EVEN AFTER THE MANUAL EXTENSION. AFTER ARRIVAL; ONE OF THEIR TECHNICIANS INFORMED HIM THERE WAS A CLUMP OF OLD; DRIED; CAKED GREASE ON AND AROUND THE LOCK SENSOR AND TARGET. TECHNICIAN BELIEVED THE CAKED GREASE HAD CAUSED MOVEMENT OF THE LOCK SENSOR; CONTRIBUTING TO THE LACK OF NOSE GEAR LOCK INDICATION. A SENSOR TO TARGET GAP CHECK WAS ACCOMPLISHED. THIS EVENT WAS CONSIDERED AN INDICATION PROBLEM; NOT A MANUAL EXTENSION PROBLEM; SO THE AIRCRAFT WAS RELEASED WITHOUT AN RII INSPECTION PER THE AIRCRAFT MAINTENANCE MANUAL AND THEIR RII LIST. SINCE THE INCIDENT HOWEVER; HIS CARRIER HAS ADDED THE MANUAL EXTENSION SYSTEM TO THEIR REQUIRED INSPECTION ITEM (RII) LIST WHENEVER THE MANUAL EXTENSION IS USED.

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.