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Aviation Accident

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NTSB Identification: ATL02LA035
The docket is stored in the Docket Management System (DMS). Please contact Records Management Division
Accident occurred Thursday, January 10, 2002 in Oak Hill, FL
Probable Cause Approval Date: 05/30/2003
Aircraft: Springer Longbow 150, registration: N150LB
Injuries: 1 Fatal.

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 airplane was observed to fly a circling maneuver, and then dive vertically into the ground with the engine running. Forensic toxicology revealed 31 percent carbon monoxide in the pilot's blood. Metallurgical examination of the exhaust muffler and heat exchanger assembly revealed the wall of the muffler was fractured through in the area where the exhaust pipe was welded to the muffler canister. Fracture surfaces darkly colored by corrosion were observed at the edge of the weld bead around the exhaust port over a circumference of approximately 180 degrees, and along several cracks branching outward from the weld bead. Fracture surfaces that displayed no corrosion branched out circumferentially from the corroded fracture surfaces on either end of the exhaust outlet. A review of Federal Aviation Administration Advisory Circular AC65-12A revealed in Chapter 2, Induction and Exhaust Systems, Exhaust System Repairs: "It is generally recommended that exhaust stacks, mufflers, tailpipes, etc., be replaced with new or reconditioned components rather than repaired".

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
  • The improper modification of the exhaust muffler which resulted in fractures that enabled the contamination of the cabin heating and ventilation system. The pilot subsequently became incapacitated by carbon monoxide poisoning, and the airplane descended uncontrolled into terrain.