NTSB Identification: SEA98FA092.
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Accident occurred Tuesday, June 09, 1998 in HILLSBORO, OR
Probable Cause Approval Date: 01/11/2000
Aircraft: Cessna T210N, registration: N199JM
Injuries: 2 Fatal.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
The pilot-in-command reported a power loss on approach to the runway. The aircraft passed through the tops of trees approximately 150 feet beyond, and entered a stall/spin maneuver, impacting a power line and the ground approximately 2,800 feet short of the runway threshold. The flaps and landing gear were in a retracted position. Post-crash examination revealed the crankshaft separated in fatigue which originated from a circumferential gouge mark on the aft face of the #2 cheek at an area located outboard of the forward radius of the #1 rod journal. The circumferential gouge mark on the crankcheek was consistent with the connecting rod shifting forward during engine operation. The rub marks on the cheek walls of the #1 connecting rod were consistent with tight piston pin bushing to piston pin clearance. Additionally, the bushings for all the connecting rods were undersize. Airframe/engine logs revealed a top overhaul of the engine approximately 23 hours prior to the crankshaft failure, during which the piston pins were replaced but the connecting rod bushings were not. No dimensional check of the bushings was made or required at that time. The engine was overhauled 515 hours previous to the top overhaul. The manufacturer's overhaul manual specifies that the new bushings should be reamed to the specified (inside) diameter. Post-crash examination of the engine revealed non-standard connecting rod cotter keys and light fretting between the engine case halves.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: Improper installation (bushing), mechanical binding (bushing), mechanical binding (connecting rod), and fatigue within the crankshaft. Contributing factors were inadequate major (engine) overhaul and trees. Full narrative available
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