Delta Engine Cutaway

Compressor - The compressor assembly consists of a compressor front support, shroud housing, diffuser, rear support assembly, centrifugal impeller, scroll assembly, mount assembly and bearings. The front support encloses the front bearing and supports it through five hollow inlet struts. The struts are hollow to permit anti-icing using compressor discharge air; also, to permit introduction of oil to and from the compressor front bearing. The compressor rear bearing is mounted in the rear support assembly and is lubricated from the gearbox.

Combustion Section - The combustion section consists of an outer combustion case and a combustion liner. The combustion liner is located in the outer combustion case. The liner is supported and oriented at the forward end by the gas producer turbine first stage nozzle vane assembly and at the rear by the fuel nozzle. The fuel nozzle is mounted in the aft end of the outer combustion case. The igniter plug is mounted near the aft end of the case. Air enters the single combustion liner at the aft end through holes in the liner dome and skin. The air is mixed with fuel sprayed from the fuel injector and combustion takes place. Combustion gases move forward out of the combustion liner to the first-stage gas producer turbine nozzle.

Turbine - The turbine consists of a gas producer turbine support, a power turbine support, a gas producer turbine rotor, a power turbine rotor and a turbine and exhaust collector support. The turbine is mounted between the combustion section and the power and accessory gearbox. The two-stage gas producer turbine drives the compressor and accessory gear train. The two-stage power turbine drives the spare pad, Permanent Magnet Alternator (PMA) pad and furnishes the output power of the engine. The expanded gas discharges in an upward direction through the turbine and exhaust collector support. The rear engine mount is located on the bottom rear of the turbine.

Power and Accessory Gearbox - The main power and accessory drive gear trains are enclosed in a single gear case. The gear case servers as the structural support of the engine. All engine components including the engine-mounted accessories are attached to the case. A two-stage helical and spur gear set is used to reduce rotational speed from 30,650 rpm at the power turbine to 6016 rpm at the output drive spline.

The gas producer gear train drives the compressor, hydromechanical unit (HMU), the pressure and scavenge oil pump (inside the gearbox), and a pad for an optional airframe furnished gas producer tachometer-generator. In addition to providing output power of the engine, the power turbine gear train drives the permanent magnet alternator (PMA), a pad for an optional airframe furnished power turbine tachometer-generator, and a spare pad on the rear of the gearbox. The gearbox also contains two engine furnished dual winding monopole pickups. One of the pickups is used to measure gas producer speed; the other is used to measure power turbine speed. On each pick-up, both coils provide an input signal to the ECU, and one of the signals is shared with the airframe.

Fuel System - The HMU (Hydromechanical Unit), Low Pressure Fuel Filter, and Fuel Nozzle are the major fuel system components.

Control System - A Full Authority Digital Electronic Control (FADEC) system is installed on the 250-C30R/3 engine. The FADEC is a single channel control, with a hydromechanical back-up (manual mode). It has engine torque, temperature and speed limiting capability. The FADEC system has two main components. The Electronic Control Unit (ECU) is airframe mounted. The ECU monitors, controls and limits engine speed, fuel flow, acceleration rate, temperature, torque and other engine parameters. An engine-mounted Permanent Magnet Alternator (PMA) provides all required electrical power to the ECU a power turbine speeds of 85% and above. The second FADEC component is the Hydromechanical Unit (HMU). The HMU is engine mounted and driven by the N1 gear train. The HMU includes the fuel metering unit and both a boost stage (high performance liquid ring) fuel pump and main fuel pump (gear stage). A fuel filter is located between the boost and main pump stages. In manual mode, the HMU provides altitude biased and slew rate limited fuel flow as a function of power level angle.

Lubrication System - The lubrication system is a circulating dry sump type with an external reservoir and heat exchanger mounted and furnished by the airframe manufacturer. A gear-type pressure and scavenge pump assembly is mounted within the gearbox.

Ignition System - The ignition system consists of a harness, a solid-state, low tension, capacitor discharge ignition exciter, a spark igniter lead, and a shunted surface-gap spark igniter. The system derives its input power from an airframe furnished 14-29 Vdc power source. The ignition system transfers energy to the combustible fuel mixture. Energy is provided in the form of high temperature-high voltage arcs at the spark igniter gaps. These arcs ignite the fuel mixture.

Temperature Measurement System - The temperature measurement system consists of four chromel-alumel single junction thermocouples in the gas producer turbine outlet and an associated integral harness. The voltages of the four thermocouples are electrically averaged in the assembly. the harness terminates at a junction block on the aft side of the horizontal fireshield. The engine electrical harness and the aircraft indicator harness connect to this junction box.

Anti-icing system - The compressor inlet guide vanes and front bearing support hub are the only engine components with anti-icing provisions. Anti-icing is provided by the use of compressor discharge air which is taken through a valve on the compressor scroll. The air shut-off valve is solenoid controlled and is designated to fail to the "ON" position (energized "OFF").

250-C30R/3 Engine Ratings

Design power output (Takeoff) 650 shp (485 kW)

Design speeds:

Gas producer (N1) 100% (51,000 rpm)

Power turbine (N2) 100% (30,650 rpm)

Power output shaft 6,016 rpm


Length 43.198 in. (1,097 mm)

Height 25.130 in. (653 mm)

Width 21.996 in. (559 mm)

Max. Engine Weight (dry) 274 lb (124 kg)

Max. Oil Consumption Appx. 1qt/5hr (0.05 gal/hr-0.19 l/hr)