NTSB Identification: MIA96IA109.
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Scheduled 14 CFR
Incident occurred Thursday, March 28, 1996 in JACKSONVILLE, FL
Probable Cause Approval Date: 09/24/1996
Aircraft: Beech 1900D, registration: N29YV
Injuries: 2 Uninjured.
NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.
Shortly after takeoff a counterweight and clamp separated from one propeller blade on the right propeller. The separated counterweight and clamp struck the adjacent blade and caused the blade to separate about 12 inches from the hub. The resultant imbalance caused severe vibration from the right engine. The propeller governor struck the engine cowling and broke into pieces. The flight crew shutdown the engine using the condition lever. The propeller did not feather when commanded by the flight crew, and it continued to windmill causing vibration and drag until landing. Metallurgical examination indicated a blade counterweight clamp screw failed causing the clamp to separate. The screw fracture surface initiated at the screw threads and had features typical of intergranular cracking. Cadmium, which is used as a plating on the screw after manufacturer, was present on the fracture surface.
The National Transportation Safety Board determines the probable cause(s) of this incident to be: Failure of a blade counterweight clamp retaining screw due to cadmium embrittlement which occurred during the manufacture process. This resulted in the counterweight clamp separating and striking the adjacent blade causing it to separate. Full narrative available
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