CE510 pilot reports landing gear indication malfunction during practice approach. Crew diverted back...

Attributes
ACN	915355
Time
Date	201010
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	Cessna Citation Mustang (C510)
Operating Under FAR Part	Part 91
Flight Phase	Final Approach
Route In Use	Visual Approach
Flight Plan	IFR
Component
Aircraft Component	Gear Up Lock
Person 1
Function	Instructor Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Flight Engineer Flight Crew Multiengine Flight Crew Instrument Flight Crew Flight Instructor
Experience	Flight Crew Last 90 Days 75 Flight Crew Total 16000 Flight Crew Type 75
Events
Anomaly	Aircraft Equipment Problem Less Severe

Narrative:

On approach extended landing gear and got 3 green lights and one red gear not locked light. Advised tower of situation and they suggested a fly by which we did and they said the gear appeared down. Then went around and got vectors as we ran the abnormal/emergency checklist. Recycled the gear and still got the same indications. Troubleshooting seemed to indicate a high likelihood that the gear was functioning normally with a gear up-latch switch the only malfunction. We had adequate fuel and the weather was not a factor and no overriding emergency condition existed; so decided to return to our home base where maintenance was available. When we manually lowered the gear we got the same indications; 3 green lights and one gear unlocked light. Declared an emergency and made an uneventful landing. Maintenance confirmed when repair was made; that the malfunction was a failed gear uplock switch on the left main gear.

Original NASA ASRS Text

Title: CE510 pilot reports landing gear indication malfunction during practice approach. Crew diverted back to their home field and landed after manual extension and trouble shooting lead them to believe that an up-latch switch failed.

Narrative: On approach extended landing gear and got 3 green lights and one red gear not locked light. Advised Tower of situation and they suggested a fly by which we did and they said the gear appeared down. Then went around and got vectors as we ran the abnormal/emergency checklist. Recycled the gear and still got the same indications. Troubleshooting seemed to indicate a high likelihood that the gear was functioning normally with a gear up-latch switch the only malfunction. We had adequate fuel and the weather was not a factor and no overriding emergency condition existed; so decided to return to our home base where maintenance was available. When we manually lowered the gear we got the same indications; 3 green lights and one gear unlocked light. Declared an emergency and made an uneventful landing. Maintenance confirmed when repair was made; that the malfunction was a failed gear uplock switch on the left main gear.

Data retrieved from NASA's ASRS site as of April 2012 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.