Accident Sikorsky S-58BT N439DS, Monday 16 July 1990

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Date:	Monday 16 July 1990
Time:	10:30 LT
Type:	Sikorsky S-58BT
Owner/operator:	Skyline Helicopters
Registration:	N439DS
MSN:	58-658
Engine model:	P&W T400-CP-400
Fatalities:	Fatalities: 0 / Occupants: 1
Other fatalities:	0
Aircraft damage:	Substantial
Category:	Accident
Location:	Ovando, MT - United States of America
Phase:	Taxi
Nature:	Unknown
Departure airport:	Canyon Creek, MT
Destination airport:
Investigating agency:	NTSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
DURING AN EXTERNAL LOAD LOGGING OPERATION, THE PILOT HAD JUST TAKEN OFF FROM REFUELING AND WAS PREPARING FOR ANOTHER LOAD PICK- UP WHEN THE NUMBER ONE ENGINE LOST POWER AND FLAMES WERE OBSERVED SHOTTING OUT FROM THE EXHAUST. THE PILOT TRIED TO FLY THE HELICOPTER ON ONE ENGINE TO A LANDING AREA, HOWEVER, RPM WAS DROPPING. THE PILOT INITIATED AN AUTOROTATION WHICH RESULTED IN A HARD LANDING.

Probable Cause: THE PILOT DID NOT MAINTAIN ROTOR RPM AFTER A COMPRESSOR ASSEMBLY BLADE FAILURE. A RELATED FACTOR WAS AN INADEQUATE AUTOROTATION RESULTING IN A HARD LANDING.

Accident investigation: