NTSB Identification: LAX06TA284.
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Accident occurred Monday, September 04, 2006 in Happy Camp, CA
Probable Cause Approval Date: 09/27/2007
Aircraft: Bell 212, registration: N873HL
Injuries: 1 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this public aircraft accident report.
An engine fire warning light illuminated in the cockpit and the pilot observed smoke coming from the helicopter. He pulled the fire extinguisher handle on the number 2 engine and made a rapid descent to the airport. The pilot dropped the long line and landed without further incident. A post-landing examination of the helicopter revealed that the external surfaces of the Number 2 engine were covered in soot. A hole, which appeared to originate inside the engine, was observed on the gas generator case at the 5 o'clock position (aft looking forward). Post accident disassembly and inspection was performed on the number 2 engine. During the teardown, investigators found foreign debris, consistent in appearance to a stator vane, lodged in a diffuser pipe. The diffuser pipe, which directs compressor discharge air to the combustion area, was located at approximately the 5 o'clock position (aft looking forward). Further inspection revealed a fractured stator vane in the compressor second stage stator assembly. Due to impact and heat damage to the stator vane fracture surface, the cause of cracking could not be determined. Pratt & Whitney Canada investigators, in the presence of Federal Aviation Administration inspectors, concluded the following. "The perforation of the gas generator case was most likely caused by a disturbance of compressed air flow from the diffuser pipes. The restriction in airflow caused by the lodged stator vane limited the flow of combustion liner cooling air, resulting in a localized increase in temperature and subsequent burning through the combustion liner and the gas generator case." The engine teardown and inspection revealed no other significant anomalies.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: Failure of compressor second stage stator vane for undetermined reasons while maneuvering. Full narrative available
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