Aviation Accident Summaries

Aviation Accident Summary NYC95LA142

NEW YORK, NY, USA

Aircraft #1

N206GS

BELL 206-BIII

Analysis

THE PILOT STARTED THE ENGINE WITH ONE MAIN ROTOR BLADE TIED DOWN. AS THE ENGINE ACCELERATED, THE PILOT NOTICED THAT THE MAIN ROTOR BLADE WAS NOT TURNING AND ATTEMPTED TO ABORT THE START; HOWEVER, AT THAT INSTANT, THE HELICOPTER, '...JUMPED INTO THE AIR AND YAWED VIOLENTLY....' THE MAIN ROTOR BLADE HAD FRACTURED AND THE TIE DOWN HOOK ON THE END OF THE BLADE WAS STRAIGHTENED. THE REAR CROSS TUBE WAS DRIVEN INTO THE LOWER FUSELAGE AND RUPTURED THE FUEL TANK. THE PILOT REPORTED THAT HE WAS DISTRACTED BY THOUGHTS ABOUT THE IMPENDING FLIGHT.

Factual Information

On July 6, 1995, at 1002 eastern daylight time, a Bell 206- BIII, N206GS, operated by Liberty Helicopters, Inc., was substantially damaged during engine start, at the 30th Street Heliport, Manhattan, New York, New York. The commercial pilot was not injured. Visual meteorological conditions prevailed, and no flight plan had been filed for the positioning flight which was conducted under 14 CFR Part 91. In the NTSB Accident Report, the pilot stated: ...I asked to be relieved of this mission as there was another qualified pilot present. My request to be relieved from this mission was refused, and I was told...that I was to do this mission. I, under protest and a great deal of duress, and in fear of being fired, went out to the aircraft. I went to the helicopter and installed the dual controls as well as a walk around the helicopter. I had every intention of untying the main blades, but, by mistake, did not remember to untie them...As the start procedure continued, the N1 seemed to be lagging well below what was normal. As the N1 approached 25 percent, the blades were not turning. I immediately attempted to abort the start. At that very second, the aircraft jumped into the air and yawed violently, throwing me away from the controls. I then was able to regrasp the throttle and shut down the engine.... The FAA reported that the main rotor blade was tied to the tail boom, with a nylon strap and metal hook, which were interconnected. The hook was placed in a retaining hole on the end of the main rotor blade. The strap was wrapped around the tail boom, in front of the tail rotor blades. As the engine RPMs increased, the main rotor blade failed, about 4 feet outboard of the yoke. The blade remained attached at the trailing edge. The helicopter bounced several times, and the rear cross tube was driven into the fuel tank, which ruptured. The bottom of the vertical fin and tail rotor blades contacted the ground. The shaft between the engine and transmission was fractured, and the pitch link control rods to the main rotor blades were fractured. In addition, the metal hook on the tiedown was found to be straightened. According to Bell Helicopters, a pre-flight item was to ensure that the main rotor blade was not tied down prior to engine start.

Probable Cause and Findings

The pilot' inadequate preflight inspection. A factor was the pilot's diverted attention.

 

Source: NTSB Aviation Accident Database

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