Narrative:

During climb out of ZZZ; I noticed a subtle aircraft yawing from side to side; about what you might feel in light chop. We checked all systems; and at the time; I thought maybe the yaw dampener was causing this. Before we did much else; the slight movement went away. We had just made a turn from approximately 210 degrees to direct ZZZ1 on course. No other anomalies were noted. During our descent over ZZZ2; we flew into the cloud tops and simultaneously felt a thud under the aircraft. I called the flight attendants and they also had heard the noise. It seemed to have come from under the galley; according to them. I called maintenance and they met the aircraft. The in-flight noise at the time was thought to have been maybe come from the fwd cargo; forward sliding tray not being locked in place. While the mechanics were investigating that possibility; the first officer on his walk around discovered the missing left inboard gear door. I'm not exactly sure now what caused the noise during the descent. Callback conversation with reporter revealed the following information: the reporter stated the fwd left inboard main landing gear door hinge had failed. When informed by the analyst of the airworthiness directive on the inboard landing gear door inspection requirements; the reporter stated; 'yes; but the note only covers door structure and not hinge cracks or hinge failures.' the problem is that during a walk around inspection; the fwd door hinge cannot really be seen.

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Original NASA ASRS Text

Title: A CRJ-700 FLT CREW NOTED SUBTLE YAWING ON CLB AND; LATER DURING DSCNT A LOUD 'THUD' WAS HEARD. ON GND INSPECTION FOUND THE L INBOARD MAIN LNDG GEAR DOOR MISSING.

Narrative: DURING CLB OUT OF ZZZ; I NOTICED A SUBTLE ACFT YAWING FROM SIDE TO SIDE; ABOUT WHAT YOU MIGHT FEEL IN LIGHT CHOP. WE CHKED ALL SYSTEMS; AND AT THE TIME; I THOUGHT MAYBE THE YAW DAMPENER WAS CAUSING THIS. BEFORE WE DID MUCH ELSE; THE SLIGHT MOVEMENT WENT AWAY. WE HAD JUST MADE A TURN FROM APPROX 210 DEGS TO DIRECT ZZZ1 ON COURSE. NO OTHER ANOMALIES WERE NOTED. DURING OUR DSCNT OVER ZZZ2; WE FLEW INTO THE CLOUD TOPS AND SIMULTANEOUSLY FELT A THUD UNDER THE ACFT. I CALLED THE FLT ATTENDANTS AND THEY ALSO HAD HEARD THE NOISE. IT SEEMED TO HAVE COME FROM UNDER THE GALLEY; ACCORDING TO THEM. I CALLED MAINT AND THEY MET THE ACFT. THE INFLT NOISE AT THE TIME WAS THOUGHT TO HAVE BEEN MAYBE COME FROM THE FWD CARGO; FORWARD SLIDING TRAY NOT BEING LOCKED IN PLACE. WHILE THE MECHANICS WERE INVESTIGATING THAT POSSIBILITY; THE FO ON HIS WALK AROUND DISCOVERED THE MISSING L INBOARD GEAR DOOR. I'M NOT EXACTLY SURE NOW WHAT CAUSED THE NOISE DURING THE DSCNT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE FWD L INBOARD MAIN LNDG GEAR DOOR HINGE HAD FAILED. WHEN INFORMED BY THE ANALYST OF THE AIRWORTHINESS DIRECTIVE ON THE INBOARD LNDG GEAR DOOR INSPECTION REQUIREMENTS; THE RPTR STATED; 'YES; BUT THE NOTE ONLY COVERS DOOR STRUCTURE AND NOT HINGE CRACKS OR HINGE FAILURES.' THE PROB IS THAT DURING A WALK AROUND INSPECTION; THE FWD DOOR HINGE CANNOT REALLY BE SEEN.

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.