NTSB Identification: ATL02FA072.
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Accident occurred Monday, April 01, 2002 in Gainesville, GA
Probable Cause Approval Date: 11/25/2003
Aircraft: North American T-6-AT6D, registration: N7471C
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 and CFI were conducting a series of touch and go landings when smoke was seen streaming from the right lower section of the engine cowling after take off. Witnesses also reported hearing a rough engine condition. At approximately the same time, the pilot initiated a left turn towards the airport. The airplane was last seen in a nose low attitude. The airplane disappeared below the tree line and collided with the ground. Examination of the engine revealed damage throughout the supercharger assembly. The supercharge impeller was not totally secure on the impeller shaft. The impeller shaft retainer nut was loose on its shaft. This nut as well as the impeller shaft gear-teeth showed signs of wear. These teeth were worn down and disfigured. Both the aluminum cover plate and the bottom of the impeller blades showed signs of circular scraping. Small pieces of metal were found throughout the engine. Disassembly of the oil filter revealed metal shavings throughout. No metal parts or gear teeth were found in the oil sump.

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

A loss of engine power following a supercharger bearing failure and subsequent collision with the ground while maneuvering for an emergency landing.

Full narrative available

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