Exhaust outlet Fuel nozzle Free (power) turbine Compressor turbine (gas producer) Centrifugal compressor Air inlet Igniter Fuel nozzle Igniter Accessory gearbox Three stage axial flow compressor Reduction gearbox Propeller drive shaft Figure 14-5.  Split shaft/free turbine engine. lever is located at the far right of the power quadrant. But  the condition lever on a turboprop engine is really just an  on/off valve for delivering fuel. There are HIGH IDLE and  LOW IDLE positions for ground operations, but condition  levers have no metering function. Leaning is not required in  turbine engines; this function is performed automatically by  a dedicated fuel control unit. centrifugal compressor stage through radial diffusers before  entering the combustion chamber, where the flow direction  is actually reversed. The gases produced by combustion  are once again reversed to expand forward through each  turbine stage. After leaving the turbines, the gases are  collected in a peripheral exhaust scroll and are discharged  to the atmosphere through two exhaust ports near the front  of the engine. A pneumatic fuel control system schedules fuel flow to  maintain the power set by the gas generator power lever.  Except in the beta range, propeller speed within the governing  range remains constant at any selected propeller control lever  position through the action of a propeller governor. Engine instruments in a split shaft/free turbine engine  typically consist of the following basic indicators. [Figure 14-7] The accessory drive at the aft end of the engine provides  power to drive fuel pumps, fuel control, oil pumps, a starter/ generator, and a tachometer transmitter. At this point, the  speed of the drive (N$_{1}$) is the true speed of the compressor  side of the engine, approximately 37,500 rpm. Powerplant (engine and propeller) operation is achieved  by three sets of controls for each engine: the power lever,  propeller lever, and condition lever.  [Figure 14-6]  The  power lever serves to control engine power in the range  from idle through takeoff power. Forward or aft motion of  the power lever increases or decreases gas generator rpm  (N$_{1}$) and thereby increases or decreases engine power. The  propeller lever is operated conventionally and controls the  constant-speed propellers through the primary governor. The  propeller rpm range is normally from 1,500 to 1,900. The  condition lever controls the flow of fuel to the engine. Like  the mixture lever in a piston-powered airplane, the condition  The ITT indicator gives an instantaneous reading of engine  gas temperature between the compressor turbine and the  power turbines. The torquemeter responds to power lever  movement and gives an indication in foot-pounds (ft/lb)  of the torque being applied to the propeller. Because in the  free turbine engine the propeller is not attached physically  to the shaft of the gas turbine engine, two tachometers are  justified—one for the propeller and one for the gas generator.  The propeller tachometer is read directly in revolutions per  minute. The N$_{1}$ or gas generator is read in percent of rpm.  In the Pratt & Whitney PT-6 engine, it is based on a figure  of 37,000 rpm at 100 percent. Maximum continuous gas  generator is limited to 38,100 rpm or 101.5 percent N$_{1}$. • ITT indicator •  Torquemeter • Propeller tachometer •  N$_{1}$ (gas generator) tachometer • Fuel flow indicator • Oil temperature/pressure indicator 14-6