The Pratt & Whitney T73 (company designation JFTD12) is a turboshaft engine. Based on the JT12A, the T73 powered the Sikorsky CH-54 Tarhe and its civil counterpart Sikorsky S-64 Skycrane flying crane heavy-lift helicopters. Turboshaft versions for naval use are known as the FT12.
T73-P-1Basic military model, rated at 4,500 horsepower (3,355 kW) takeoff power and 4,000 horsepower (2,982 kW) maximum continuous power
T73-P-700Higher-power military model with improved internal components; rated at 4,800 horsepower (3,579 kW) takeoff power and 4,430 horsepower (3,303 kW) maximum continuous power
JFTD12A-4ACivilian equivalent of T73-P-1
JFTD12A-5ACivilian equivalent of T73-P-700
Sikorsky CH-54 Tarhe (T73)Sikorsky S-64 Skycrane/Erickson Air-Crane S-64 Skycrane (JTFD12)Data from FAA Type Certificate E15EA
Type: TurboshaftLength: 107.0 in (2,718 mm)Diameter: 30.0 in (762 mm) maximumDry weight: 966 lbs (438 kg)Compressor: nine stage axial compressorCombustors: eight cans in annular configurationTurbine: axial two stage gas generator turbine and axial two stage free turbineFuel type: aviation kerosene conforming to MIL-I-5161 E Grade I or IIMaximum power output: 4,500 horsepower (3,355 kW) takeoff, 4,000 horsepower (2,982 kW) maximum continuous; at sea level at or below -8°C (17°F)Turbine inlet temperature: 688°C (1270°F)Power-to-weight ratio: 4.66 hp/lb (7.66 kW/kg) 
