Shaft

INTRODUCTION TO A SINGLE-SHAFT TURBOPROP ENGINE
This section describes the components, component assemblies, systems and operation of a typical single shaft turbopropeller engine. This engine is rated approximately 4900 E.S.H.P. at Standard Day conditions at 100% RPM and a maximum turbine inlet temperature of over 1050C. The engine consists of a power section, a reduction gear, and atorquemeter assembly. The propeller is mounted on a single rotation propeller shaft. The following definitions apply to this engine. FRONT: REAR: TOP: The propeller end. The exhaust end. Determined by the breather located at the forward end of the power section.

BOTTOM: Determined by the power section accessory drive housing, which is located at the forward end of the power section. RIGHT AND LEFT:Determined by standing at the rear of the engine, facing forward. ROTATION: The direction of rotation is determined when standing at the rear of the engine, facing forward. The power section rotors rotate in a counterclockwise direction. The propeller rotation is clockwise. ACCESSORIES ROTATION: accessory. Determined by facing the mounting pad of each

COMBUSTION LINER NUMBERING: The combustionliners are numbered from one through six in a clockwise direction when viewing the engine from the rear. COMPRESSOR AND TURBINE STAGES NUMBERING: Numbered beginning from the front of the power section toward the rear. MAIN ROTOR BEARINGS: The main rotor bearings of the power section are the front compressor rotor bearing, the rear compressor rotor bearing, the front turbine rotor bearing, and the rearturbine rotor bearing. The bearings are numbered one through four. In addition to these main rotor bearings, there is a compressor extension shaft bearing. SPARK IGNITER LOCATION: Two spark igniters are used. These are located in combustion liners numbers two and five.

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MAJOR ENGINE ASSEMBLIES The engine consists of a power section, torquemeter assembly, and a reduction gear assembly. Thepower section is attached to the reduction gear assembly by means of the torquemeter assembly and two tie struts. The power section is divided into two subparts, the "cold section" and the "hot section." The "cold section" consists of the compressor and accessory drive housing assemblies. It is so named because the temperatures that exist in this portion of the power section are lower than thetemperatures that are present in the combustion and turbine assemblies. The "hot section" is composed of the combustion and turbine sections. The temperatures of this portion of the power section are high because of combustion of the fuel/air mixture and exhausting gases. The compressor assembly in this example engine is an axial flow type, incorporating a fourteen-stage compressor rotor and vaneassembly encased in a casing. The air inlet housing, secured to the forward end of the compressor casing, receives air from the aircraft duct and directs this air to the compressor rotor. Provisions are made for the anti-icing of the air inlet housing struts and the inlet vanes that guide air into the rotor. A compressor air diffuser at the rear end of the compressor casing guides the air from therotor into the combustor. The accessory drive housing assembly, attached on the bottom of the air inlet housing, is driven from the compressor rotor assembly. Through a gear train, the power section RPM is reduced to that required to drive the accessories. There is a speed-sensitive valve, a speed-sensitive control, and an oil pump mounted on the front cover of the accessory drive housing. Mountedon the rear side of the accessory drive housing are the fuel control, fuel pump, and external scavenge oil pump. The combustion assembly (also called the combustor), attached to the compressor diffuser, incorporates six cylindrical combustion liners positioned between the inner and outer combustion casings. The combustion liners mix the fuel and air, control combustion, and guide the exhausting...