ANCHORAGE, AK, USA
N173RV
NIHON YS-11A-600
THE CREW OF FOUR WERE ON A TRAINING FLIGHT AND WERE PREPARING TO PERFORM APPROACH TO LANDING STALLS. DURING THE MANEUVER, THEY NOTICED THE NOSE GEAR WOULD NOT EXTEND. UNABLE TO EXTEND THE NOSE GEAR, THEY LANDED WITH THE NOSE GEAR UP CAUSING MINOR DAMAGE TO THE AIRPLANE. SUBSEQUENT EXAMINATION REVEALED THAT THE RIVETS WHICH RETAIN THE CENTERING CAM SHEAR PINS WERE SHEARED. THE SHEAR PINS WERE NOT SHEARED. AN EXAMINATION BY MITSUBISHI HEAVY INDUSTRIES, NAGOYA AIRPLANE WORKS, INDICATED THAT THE SHEAR PINS MAY HAVE BEEN INSTALLED IN REVERSE. THE OVERHAUL MANUAL ALSO CONTAINED AMBIGUOUS INFORMATION CONCERNING THE INFORMATION. THE GRAPHICAL DISPLAY SHOWED THE INSTALLATION INCORRECTLY, BUT THE TEXT EXPLAINED THE INSTALLATION CORRECTLY.
A JAMMED NOSE GEAR DUE TO INCORRECT INSTALLATION OF THE SHEAR PIN. CONTRIBUTING TO THE ACCIDENT WAS THE INSUFFICIENTLY DEFINED MAINTENANCE PROCEDURE.
Source: NTSB Aviation Accident Database
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