Air carrier cargo aircraft has gear unsafe light activated even with 3 green.

Attributes
ACN	309345
Time
Date	199506
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : yxu
State Reference	ON
Altitude	msl bound lower : 2300 msl bound upper : 2300
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : yxu
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	descent : approach landing other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument pilot : cfi
Experience	flight time last 90 days : 60 flight time total : 2020 flight time type : 800
ASRS Report	309345
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : declared emergency other other
Consequence	Other
Supplementary
Primary Problem	Aircraft

Narrative:

When calling for 'gear down, final check' gear was lowered and 'gear unsafe' light failed to extinguish when gear cycle finished. 3 green were illuminated as well. Missed approach was executed and we held to the north of yxu class D airspace. Numerous attempts to resolve situation in coordination with company maintenance and chief pilot via radio contact through yxu and controller were unsuccessful. Yxu tower authority/authorized overflt of airport for visual inspection of gear position and confirmed it to be lowered. After determining that all resources had been exhausted in trouble-shooting 'gear unsafe' warning light. A landing decision at yxu was made on the basis of WX deteriorating at home base, fuel remaining, and good airport conditions. A normal landing followed by uneventful taxi was end result. Fortunately, having plenty of fuel, fair WX at yxu, and controller cooperation gave us plenty of time to evaluate and trouble-shoot condition. We were confident that everything we could do had been done before landing. One hindrance was our inability to contact air carrier for direct radio communication due to our altitude. Yxu ground controller was helpful in relaying information from his land-line to our company.

Original NASA ASRS Text

Title: ACR CARGO ACFT HAS GEAR UNSAFE LIGHT ACTIVATED EVEN WITH 3 GREEN.

Narrative: WHEN CALLING FOR 'GEAR DOWN, FINAL CHK' GEAR WAS LOWERED AND 'GEAR UNSAFE' LIGHT FAILED TO EXTINGUISH WHEN GEAR CYCLE FINISHED. 3 GREEN WERE ILLUMINATED AS WELL. MISSED APCH WAS EXECUTED AND WE HELD TO THE N OF YXU CLASS D AIRSPACE. NUMEROUS ATTEMPTS TO RESOLVE SIT IN COORD WITH COMPANY MAINT AND CHIEF PLT VIA RADIO CONTACT THROUGH YXU AND CTLR WERE UNSUCCESSFUL. YXU TWR AUTH OVERFLT OF ARPT FOR VISUAL INSPECTION OF GEAR POS AND CONFIRMED IT TO BE LOWERED. AFTER DETERMINING THAT ALL RESOURCES HAD BEEN EXHAUSTED IN TROUBLE-SHOOTING 'GEAR UNSAFE' WARNING LIGHT. A LNDG DECISION AT YXU WAS MADE ON THE BASIS OF WX DETERIORATING AT HOME BASE, FUEL REMAINING, AND GOOD ARPT CONDITIONS. A NORMAL LNDG FOLLOWED BY UNEVENTFUL TAXI WAS END RESULT. FORTUNATELY, HAVING PLENTY OF FUEL, FAIR WX AT YXU, AND CTLR COOPERATION GAVE US PLENTY OF TIME TO EVALUATE AND TROUBLE-SHOOT CONDITION. WE WERE CONFIDENT THAT EVERYTHING WE COULD DO HAD BEEN DONE BEFORE LNDG. ONE HINDRANCE WAS OUR INABILITY TO CONTACT ACR FOR DIRECT RADIO COM DUE TO OUR ALT. YXU GND CTLR WAS HELPFUL IN RELAYING INFO FROM HIS LAND-LINE TO OUR COMPANY.

Data retrieved from NASA's ASRS site as of July 2007 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.