NTSB Identification: CHI99IA096.
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Incident occurred Saturday, February 20, 1999 in TINLEY PARK, IL
Probable Cause Approval Date: 02/28/2000
Aircraft: Cessna T210R, registration: N7687U
Injuries: 3 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 of the incident airplane said that in-flight at 1800 feet above mean sea level, the engine seized, the propeller bolts sheared, the propeller fell to the ground, and that he landed the airplane without any damage to the airplane. During an inspection of the engine, a 'B' nut on the oil pressure line to the turbocharger was found loose. The cylinders in the area of the 'B' nut were found with a dark, oily substance coating them. The turbocharger and its housing were found with a dark, charred, oily substance on it. Number one, four, five, and six crankshaft journals revealed distress. The number one crankshaft journal was found blue. The number four connecting rod was found broken and colored blue. The number four cylinder head was found separated from its base. The propeller hub and engine crankshaft flange mating surfaces were found with areas of distress. Three of the studs that held the propeller to the crankshaft flange were found with their fracture initiating on opposite sides of those studs. A top overhaul was performed 85 tachometer hours prior to the accident.

The National Transportation Safety Board determines the probable cause(s) of this incident to be:

the improper installation of the pressure oil line 'B' nut by maintenance personnel. Contributing to the incident were the loose pressure oil line 'B' nut and separation of the propeller from the aircraft.

Full narrative available

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