NTSB Identification: CEN09LA132
14 CFR Part 91: General Aviation
Accident occurred Monday, January 05, 2009 in Milford, IN
Probable Cause Approval Date: 07/14/2009
Aircraft: GRUMMAN AMERICAN AVN. CORP. AA-5B, registration: N28862
Injuries: 2 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The airplane was in cruise flight when the pilot heard a "loud bang followed by a violent vibration." He secured the engine and executed a forced landing to an open field. A postaccident examination revealed that a 20-inch length of one of the propeller blades had separated. Metallurgical examination revealed a fatigue failure of the propeller blade initiating from an area of corrosion. Corrosion pitting was observed over the entire cambered surface of the blade. The propeller had accumulated 2,326 hours total time in service. The most recent annual inspection was completed approximately 2 months prior to the accident. Federal Aviation Administration publications and the manufacturer's documentation recommended a detailed visual inspection of the propeller for corrosion during an aircraft annual inspection.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: A loss of engine thrust due to the separation of a section of one of the propeller blades as a result of fatigue failure of the propeller because of corrosion. Contributing to the accident was the failure of the mechanic to detect and address the propeller corrosion during the annual inspection. Full narrative available
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