NTSB Identification: IAD98LA034.
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Accident occurred Wednesday, March 04, 1998 in HAVERHILL, MA
Probable Cause Approval Date: 03/30/2000
Aircraft: Cessna 150M, registration: N63387
Injuries: 1 Minor,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.
In level flight at 2,000 feet, the engine began running rough with an associated vibration. The CFI took control of the airplane and the vibration became stronger. After shutting down the engine, the CFI attempted to land on an abandoned runway. The airplane impacted trees approximately 100 feet beyond the departure end of the abandoned runway. Examination of the engine logbooks and discussions with the operator disclosed that the engine was 362 hours beyond Time Between Overhaul (TBO) and automotive fuel was utilized without a Supplemental Type Certificate. Disassembly of the engine revealed the number two cylinder's exhaust valve was fractured and the cylinder was cracked. An examination of the fractured exhaust valve by the Materials Laboratory Division of the National Transportation Safety Board revealed that the 'shank area immediately adjacent to the fracture was reduced in size, and the fracture features were indicative of bending overstress separation with no indications of pre-existing cracking.'
The National Transportation Safety Board determines the probable cause(s) of this accident to be: A loss of engine power due to a fractured number two cylinder exhaust valve and cracked cylinder. Contributing factors were the operator's allowance of the time between engine overhaul to be exceeded and the trees. Full narrative available
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