Narrative:

The aircraft was picked up from a maintenance facility. A new hydraulic actuator had been installed. We gave the aircraft a very good and thorough preflight and flew the aircraft toward ZZZ. As soon as we leveled off at 12000 ft; we got an antiskid inoperative light. We went through the abnormal checklist and were unable to change the situation. We then obtained a clearance back to ZZZ1; so that the people who had done the original maintenance could fix this problem. As we approached the airport and tried to extend our landing gear; we received a gear unsafe light (red) and no green light for the right gear. We recycled the gear and still had the same result. We got radar vectors and a slightly higher altitude; so that we could work on the problem. We followed the checklist and did an alternate gear extension; etc; and still the same result. We then flew by the tower and they said the right gear looked down and had the same angle as the left gear. We then asked for and received more vectors to burn off fuel in case the right gear collapsed upon landing. While we were flying around and burning fuel; we contacted the citation maintenance facility which had done the previous work to see if they had any ideas we hadn't thought of. They didn't. When we burned as much fuel as we had planned; we declared an emergency; asked for men and equipment; and asked the tower to notify citation to tow it to their facility. When we went to landing flaps; the gear warning horn blared and we landed normally. The aircraft was towed to the facility and they discovered that a cannon plug had been improperly secured and that it became loose in-flight; causing the indications. They secured it; checked everything out and we departed uneventfully to ZZZ.

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Original NASA ASRS Text

Title: C560 EXPERIENCES MULTIPLE LNDG GEAR ASSOCIATED ANOMALIES ON FIRST FLIGHT FOLLOWING MAINT. RETURN TO MAINT BASE ARPT UNDER EMERGENCY CONDITIONS DUE TO GEAR UNSAFE LIGHTS.

Narrative: THE ACFT WAS PICKED UP FROM A MAINT FACILITY. A NEW HYD ACTUATOR HAD BEEN INSTALLED. WE GAVE THE ACFT A VERY GOOD AND THOROUGH PREFLT AND FLEW THE ACFT TOWARD ZZZ. AS SOON AS WE LEVELED OFF AT 12000 FT; WE GOT AN ANTISKID INOP LIGHT. WE WENT THROUGH THE ABNORMAL CHKLIST AND WERE UNABLE TO CHANGE THE SIT. WE THEN OBTAINED A CLRNC BACK TO ZZZ1; SO THAT THE PEOPLE WHO HAD DONE THE ORIGINAL MAINT COULD FIX THIS PROB. AS WE APCHED THE ARPT AND TRIED TO EXTEND OUR LNDG GEAR; WE RECEIVED A GEAR UNSAFE LIGHT (RED) AND NO GREEN LIGHT FOR THE R GEAR. WE RECYCLED THE GEAR AND STILL HAD THE SAME RESULT. WE GOT RADAR VECTORS AND A SLIGHTLY HIGHER ALT; SO THAT WE COULD WORK ON THE PROB. WE FOLLOWED THE CHKLIST AND DID AN ALTERNATE GEAR EXTENSION; ETC; AND STILL THE SAME RESULT. WE THEN FLEW BY THE TWR AND THEY SAID THE R GEAR LOOKED DOWN AND HAD THE SAME ANGLE AS THE L GEAR. WE THEN ASKED FOR AND RECEIVED MORE VECTORS TO BURN OFF FUEL IN CASE THE R GEAR COLLAPSED UPON LNDG. WHILE WE WERE FLYING AROUND AND BURNING FUEL; WE CONTACTED THE CITATION MAINT FACILITY WHICH HAD DONE THE PREVIOUS WORK TO SEE IF THEY HAD ANY IDEAS WE HADN'T THOUGHT OF. THEY DIDN'T. WHEN WE BURNED AS MUCH FUEL AS WE HAD PLANNED; WE DECLARED AN EMER; ASKED FOR MEN AND EQUIP; AND ASKED THE TWR TO NOTIFY CITATION TO TOW IT TO THEIR FACILITY. WHEN WE WENT TO LNDG FLAPS; THE GEAR WARNING HORN BLARED AND WE LANDED NORMALLY. THE ACFT WAS TOWED TO THE FACILITY AND THEY DISCOVERED THAT A CANNON PLUG HAD BEEN IMPROPERLY SECURED AND THAT IT BECAME LOOSE INFLT; CAUSING THE INDICATIONS. THEY SECURED IT; CHKED EVERYTHING OUT AND WE DEPARTED UNEVENTFULLY TO ZZZ.

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.