NTSB Identification: CEN12IA377
14 CFR Part 91: General Aviation
Incident occurred Monday, June 18, 2012 in Lacon, IL
Probable Cause Approval Date: 07/30/2014
Aircraft: PIPER PA-28R-200, registration: N4350T
Injuries: 1 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.
The pilot reported that he was flying the airplane at 4,500 feet mean sea level with 23 inches of manifold pressure and with the engine at 2,350 to 2,400 rpm when the airplane began to abnormally vibrate. He scanned the instruments and observed no other abnormal indications. He executed an emergency landing to an airport without incident. The examination of the airplane revealed that about 6 inches of a propeller blade tip had separated from the propeller. The metallurgical examination of the fracture surface revealed that a fatigue crack had originated about 0.06 inch from the blade’s leading edge. A surface gouge was found at the origin of the fatigue crack, which indicated that the direction of the damage was from the leading to trailing edge consistent with foreign object impact to a rotating propeller. A test of the airplane’s tachometer revealed that it was indicating 50 rpm higher than the actual propeller rpm and that it had a restricted propeller operating range from 2,100 to 2,350 rpm. When the pilot set the propeller to 2,350 or 2,400 rpm using the airplane’s tachometer, the actual rpm would have been operating within the restricted rpm range.
The National Transportation Safety Board determines the probable cause(s) of this incident to be: The propeller blade’s failure due to a fatigue crack that originated from a surface gouge that resulted from foreign object damage to the propeller blade that occurred at an unknown time.
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