CL300 flight crew reports an uncommanded landing gear retraction at 200 ft during approach. A go aro...

Narrative:

We were flying the ILS in visual conditions. Fully configured; stabilized and before landing checklist completed and the gear was confirmed down three green by both myself and pilot not flying. At approximately 200 ft AGL I heard a clicking noise in the cockpit. Either simultaneously with the clicking noise or right after the noise we received the 'gear too low' warning message. I quickly glanced at the cas messages and noticed gear was in transit up. The pilot not flying called for a go a round which we executed. On the tower directed missed we climbed to 2;000 ft and were on a heading provided by tower. On the downwind leg we received the RA. I disconnected the autopilot and was preparing to follow climb commands when I glanced to the right of the plane and visually located the helicopter. As we were clear of any conflict no changes of heading or altitude was deemed necessary. On downwind we again lowered the gear; confirmed it indicated 3 green and proceeded to land visually. On final tower communicated to us that the gear was in fact down. As this was an uncommanded movement of the landing gear I don't have any suggestions for avoiding a recurrence of this event.

Original NASA ASRS Text

Title: CL300 flight crew reports an uncommanded landing gear retraction at 200 FT during approach. A go around is initiated and a TCAS RA is annunciated on downwind but evasive action is not required. On the second approach the gear handle is verified in the down detent and an uneventful landing ensues.

Narrative: We were flying the ILS in visual conditions. Fully configured; stabilized and before landing checklist completed and the gear was confirmed down three green by both myself and pilot not flying. At approximately 200 FT AGL I heard a clicking noise in the cockpit. Either simultaneously with the clicking noise or right after the noise we received the 'gear too low' warning message. I quickly glanced at the CAS messages and noticed gear was in transit up. The pilot not flying called for a go a round which we executed. On the Tower directed missed we climbed to 2;000 FT and were on a heading provided by Tower. On the downwind leg we received the RA. I disconnected the autopilot and was preparing to follow climb commands when I glanced to the right of the plane and visually located the helicopter. As we were clear of any conflict no changes of heading or altitude was deemed necessary. On downwind we again lowered the gear; confirmed it indicated 3 green and proceeded to land visually. On final Tower communicated to us that the gear was in fact down. As this was an uncommanded movement of the landing gear I don't have any suggestions for avoiding a recurrence of this event.

Data retrieved from NASA's ASRS site as of July 2013 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.

Attributes
ACN	1028148
Time
Date	201208
Local Time Of Day	0001-0600
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Challenger 300
Operating Under FAR Part	Part 135
Flight Phase	Landing
Component
Aircraft Component	Gear Extend/Retract Mechanism
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Pilot Not Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Critical

CL300 flight crew reports an uncommanded landing gear retraction at 200 ft during approach. A go around is initiated and a TCAS RA is annunciated on downwind but evasive action is not required. On the second approach the gear handle is verified in the down detent and an uneventful landing ensues.