NTSB Identification: CHI93LA365.
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Accident occurred Saturday, September 18, 1993 in AURORA, IL
Probable Cause Approval Date: 07/25/1994
Aircraft: GRUMMAN AA5B, registration: N55VL
Injuries: 1 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 PILOT DEPARTED FOR A LOCAL PLEASURE FLIGHT, AND WAS ABOUT 5 MILES SOUTH OF THE DEPARTURE AIRPORT WHEN THERE WAS A LOUD POP AND THE AIRPLANE BEGAN TO '...VIBRATE VIOLENTLY.' THE PILOT STATED THE VIBRATION BECAME MANAGEABLE WHEN HE REDUCED ENGINE POWER TO IDLE. HE REPORTED THE ENGINE LOST POWER COMPLETELY AS THE AIRPLANE GLIDED TOWARD THE SELECTED FORCED LANDING SITE. THE AIRPLANE LANDED HARD AND FLIPPED OVER DURING THE LANDING ROLL, COMING TO REST INVERTED. POSTACCIDENT INVESTIGATION REVEALED THE OUTBOARD 13.75 INCHES OF ONE PROPELLER BLADE SEPARATED DURING FLIGHT. THE SEPARATED PORTION WAS RECOVERED, AND BOTH PIECES OF THE FAILED BLADE WERE EXAMINED BY THE NTSB'S MATERIALS LAB. THE LAB'S EXAMINATION REVEALED THE CRACK ARREST POSITIONS EMANATED FROM A CAVITY ON THE FLAT FACE OF THE PROPELLER BLADE. THE PROPELLER WAS CHECKED FOR BALANCE, BLADE TRACK AND ANGLE, AND WAS PAINTED 9 1/2 MONTHS BEFORE THE ACCIDENT. THE CAVITY CONTAINED PAINT SIMILAR TO THE REST OF THE FLAT FACE OF THE BLADE.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: the fatigue failure and separation of a portion of propeller blade during cruise flight. Related factors are the damage to the flat face of the blade, and inadequate maintenance inspection of the propeller. Full narrative available
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