Narrative:

After initiation of the after takeoff checklist; it was indicated that the left main gear light remained illuminated after gear retraction. The gear was cycled and the same result was received. The flight was continued and while en route; contacted the company who asked if enough fuel to divert to ZZZ. We did; so we diverted. After consulting the emergency checklist; we both came to the conclusion that we would execute the 'emergency gear will not extend' checklist to use all possible resources to assume the gear was down. This checklist was completed just prior to landing. Upon switching to ZZZ tower; we declared an emergency as a precaution in case the gear collapsed. We performed a fly-by and the tower indicated to us that the gear appeared normal. After the fly-by we entered a left downwind pattern and made a normal landing. We elected to leave the aircraft on the runway and performed the shutdown checklist and set the parking brake. A service center technician arrived mins later; inspected the gear; and towed the aircraft off the runway. Callback conversation with reporter revealed the following information: maintenance discovered that a microswitch had failed on the left main gear causing a false gear indication.

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Original NASA ASRS Text

Title: CE560 FLT CREW REPORTS UNSAFE GEAR INDICATION AFTER GEAR RETRACTION. FLIGHT DIVERTS AND USES EMERGENCY EXTENSION PROCEDURES TO ENSURE GEAR IS DOWN PRIOR TO UNEVENTFUL LANDING.

Narrative: AFTER INITIATION OF THE AFTER TKOF CHKLIST; IT WAS INDICATED THAT THE L MAIN GEAR LIGHT REMAINED ILLUMINATED AFTER GEAR RETRACTION. THE GEAR WAS CYCLED AND THE SAME RESULT WAS RECEIVED. THE FLT WAS CONTINUED AND WHILE ENRTE; CONTACTED THE COMPANY WHO ASKED IF ENOUGH FUEL TO DIVERT TO ZZZ. WE DID; SO WE DIVERTED. AFTER CONSULTING THE EMER CHKLIST; WE BOTH CAME TO THE CONCLUSION THAT WE WOULD EXECUTE THE 'EMER GEAR WILL NOT EXTEND' CHKLIST TO USE ALL POSSIBLE RESOURCES TO ASSUME THE GEAR WAS DOWN. THIS CHKLIST WAS COMPLETED JUST PRIOR TO LNDG. UPON SWITCHING TO ZZZ TWR; WE DECLARED AN EMER AS A PRECAUTION IN CASE THE GEAR COLLAPSED. WE PERFORMED A FLY-BY AND THE TWR INDICATED TO US THAT THE GEAR APPEARED NORMAL. AFTER THE FLY-BY WE ENTERED A L DOWNWIND PATTERN AND MADE A NORMAL LNDG. WE ELECTED TO LEAVE THE ACFT ON THE RWY AND PERFORMED THE SHUTDOWN CHKLIST AND SET THE PARKING BRAKE. A SVC CTR TECHNICIAN ARRIVED MINS LATER; INSPECTED THE GEAR; AND TOWED THE ACFT OFF THE RWY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: MAINTENANCE DISCOVERED THAT A MICROSWITCH HAD FAILED ON THE LEFT MAIN GEAR CAUSING A FALSE GEAR INDICATION.

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