NTSB Identification: FTW97FA330.
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Accident occurred Wednesday, August 27, 1997 in MANILA, AR
Probable Cause Approval Date: 11/06/1998
Aircraft: Southwest Florida Aviation SW204, registration: N482SA
Injuries: 1 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 was applying pesticide to a cotton field when the outboard 9 feet of one main rotor blade separated in flight, resulting in the main rotor system separating from the main transmission mast. The in-flight separation of the main rotor blade was due to fatigue cracks emanating from a puncture through the lower surface of the blade in the leading edge area. The shape of the puncture, the crater mark above the puncture, and surrounding areas containing heavy deposits of lead residue indicated a bullet had entered the blade. The puncture had been repaired; however, manufacturer's specifications stated that this type damage is nonrepairable and the blade should be scrapped. In July 1995, the rotor blade was modified. During the modification process, the blade was inspected for damage. In April 1997, an AD requiring inspection of the blade was complied with.

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

Fatigue failure of the main rotor blade resulting in the in-flight separation of the main rotor system due to the use of an unairworthy blade, and failure of the maintenance personnel who modified the rotor blade and the mechanic who complied with the Airworthiness Directive to locate the unapproved repair. A factor was the unapproved repair of the main rotor blade.

Full narrative available

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