NTSB Identification: LAX93LA345.
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Accident occurred Monday, September 06, 1993 in AVALON, CA
Probable Cause Approval Date: 06/30/1994
Aircraft: CESSNA 172G, registration: N4143L
Injuries: 3 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 aircraft was in cruise flight about 10 miles from the island when a puff of smoke emanated from the engine cowling and the engine began to run rough. The pilot stated the aircraft could not maintain altitude and he ditched in the ocean about 100 yards off shore. The engine was disassembled and the numbers one and two connecting rods were found fractured, with heat discoloration observed on the number two bearing. Heavy fretting was found on the number two bearing surface and the associated crankcase bearing journal support. The numbers three and four cam shaft journals were observed to be visibly out of round, with heavy wear noted. Examination of the engine log book and the maintenance records from the operator revealed that the cylinder base seal for the number two cylinder was replaced on May 25, 1993, about 55 hours prior to the accident. According to the records the number two cylinder base seal 'O' ring was replaced by the aircraft owner and the work signed off by an FAA Repair Station inspector.

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

the oil starvation related failure of the number 1 and 2 connecting rods due to improper torque of the crankcase through bolts at the number 2 cylinder, which allowed fretting of the bearing surfaces and the resulting closure of the oil ports. The under torque condition was due to improper installation procedures used by the aircraft owner, and, the inadequate inspection procedures utilized by the certifying repair station.

Full narrative available

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