NTSB Identification: SEA90GA180.
The docket is stored on NTSB microfiche number 43971.
Accident occurred Tuesday, September 11, 1990 in KELLER, WA
Probable Cause Approval Date: 07/02/1993
Aircraft: BELL 204B, registration: CGKQH
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 public aircraft accident report.

THE PILOT WAS CONDUCTING FIRE FIGHTING MULTIPLE WATER DROPS USING AN EXTERNAL LOAD 'BAMBI BUCKET'. EARLY THAT DAY THE BUCKET'S CINCH STRAP HAD BEEN REPLACED. ON THIS DROP THE PILOT RADIOED THAT HE WAS HEAVY...3600 POUNDS. A PUFF OF SMOKE WAS OBSERVED, AND THE HELICOPTER CRASHED. INVESTIGATION REVEALED THAT A LOSS OF POWER HAD OCCURRED DUE TO THE LOSS OF ALL 2ND TURBINE ROTOR BLADES, PRECIPITATED BY A STRESS RUPTURE FAILURE OF 3 CONSECUTIVE BLADES INDUCED BY HIGH OPERATING TEMPERATURES. THE CINCH STRAP WAS BOUGHT AT A HARDWARE OR SPORTING GOODS STORE - IT WAS NOT THAT PROVIDED BY THE MANUFACTURER. DISASSEMBLY OF THE BUCKET CONTROL HEAD WIRING ASSEMBLY REVEALED EVIDENCE TO SUPPORT INTERMITTENT OPERATION.

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

THE TOTAL LOSS OF ENGINE POWER DUE TO TURBINE BLADE SEPARATION WHILE THE PILOT WAS OPERATING IN THE AIRCRAFT AT A GROSS WEIGHT THAT EXCEEDED PERFORMANCE SPECIFICATIONS FOR EXISTING METEOROLOGICAL CONDITIONS. FACTORS INCLUDE THE FAILURE OR INABILITY TO JETTISON THE EXTERNAL LOAD, THE USE OF AN IMPROPER CINCH STRAP, AND AN IMPROPERLY ASSEMBLED AND MAINTAINED WIRING CONNECTOR.

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