NTSB Identification: LAX97LA247.
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Accident occurred Friday, July 18, 1997 in PAGE, AZ
Probable Cause Approval Date: 12/31/1998
Aircraft: Sikorsky S-58T, registration: N47B
Injuries: 1 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The pilot was hovering with an external load, when he heard a loud noise and noticed a power loss. He turned and executed a precautionary landing with a hard touchdown. The main rotor blades flexed downward and impacted the tail boom. An inspection revealed that over half of the blades in the No. 2 power section were fractured. A metallurgical examination revealed that two consecutive blades showed evidence of solutioning and re-solidification; however, the fracture surfaces did not show similar evidence of heat distress. Discoloration was also found on the power turbine wheel at a point corresponding to the location of the two blades. The operator stated that the aircraft had flown about 138 hours since all the turbine blades were replaced. None of the pilots who had flown the aircraft since then reported experiencing any hung or hot starts.

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

an engine failure resulting from the fracture of two power turbine blades, which had been previously subjected to a hot or hung start.

Full narrative available

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