T56 Engine Virtual Training
The Rolls Royce T56 engine is asingle shaft, modular design military turboprop with a 14 stage axial flowcompressor driven by a four stage turbine. It was originally developed by theAllison Engine Company for the Lockheed C-130 transport entering production in1954.
It is now produced under Rolls-Royce which acquired Allison in 1995. Thecommercial version is designated 501-D. With an unusually long and numerousproduction run, over 18,000 engines have been produced since 1954. It haslogged over 200 million flying hours.
Specifications (T56 Series IV)
Reduction Gear Box Assembly
The engine rotates at approximately 13820 RPM. This speed is much too fast for propeller operation. To reduce the speed to a practical range, a reduction gear assembly is employed. The reduction gear assembly receives its power through the torque shaft from the power section. The torque shaft rotates at the same speed as the power section.
The total reduction to the propeller shaft is 13.54 to 1. To avoid the use of a very large gear to get this reduction, two stages are used. The first stage is 3.125 to 1. The second stage is 4.33 to 1.
The rear case of the reduction gear assembly is used for mounting accessories such as AC generator, hydraulic pump, tachometer, oil pump and pneumatic starter.
Reduction Gear Box Assembly Cutaway
Accessory Drive Housing
An accessory drive housing assembly is mounted on the bottom of the air inlet housing. It provides mounting pads on the front face for the following:
The rear face has mounting pads for the following:
Accessory gear train being driven by compressor shaft
The engine has a 14-stage axial flow compressor which supplies air for combustion, internal engine cooling, and operation of the aircraft pneumatic systems. The compressor has alternate rows of rotor blades and stator vanes. Each combination of rotor blade and stator vane is a stage of compression. As air passes through each stage of compression, it is compressed into a smaller area.
The compressor has a pessure ratio of 9.5 to 1. If the absolute pressure (psia) at the inlet to the first stage of compression is 14.7, the pressure at the 14th stage will be about 140 psia. This means the air pressure has increased 9.5 times.
The engine has a can-annular type combustion section. It is composed of an outer casing and an inner casing. Six interconnected stainless steel combustion liners are held between the two casings. Heat energy is produced by burning a fuel-air mixture in these combustion liners.
The engine has a 4-stage turbine assembly. The turbine extracts heat energy from the expanded gases produced by the combustion section and converts the energy into mechanical energy. The turbine section must withstand large changes in operating conditions and corrosive action of hot gases. These changes include constantly changing axial and radial loads, heat and vibration. The turbine section is made of titanium.
The turbine section consists of the following units: