LE FLAPS TRANSIT 3.50 64 25 0.40 LE FLAPS EXIT SPEED BRAKE AHEAD RIGHT GEAR NOSE GEAR NOSE GEAR$^{ENG 2}$ ENG 1 LEFT GEAR RIGHT GEAR LEFT GEAR SPEED BRAKES EXTENDED OIL PRESS FF N$_{2}$ N$_{1}$ 0 2 4 6 8 10 EGT TAT +13c ---- FF 32 15 0.42 3.50 OIL TEMP 17 17 OIL  QTY 1.8 2.5 VIB 66.8 768 94.5 START VALVE  OPEN 94.8 65 3 1 3 6 9 1 2 1 5 1 8 2 1 2 4 2 7 $_{ }$3 0 2350 1 FUEL EG 2350 2 11260 CTR FLAPS UP 1 2 5 10 15 25 30 40 L 0 2 4 6 8 10 28.8 Figure 15-4.  Jet engine RPM gauges. • Turbine Inlet Temperature (TIT)—the temperature of  the gases from the combustion section of the engine as  they enter the first stage of the turbine. The TIT is the  highest temperature inside a gas turbine engine and  is one of the limiting factors of the amount of power  the engine can produce. TIT, however, is difficult to  measure. Therefore, EGT, which relates to TIT, is  normally the parameter measured. • Interstage Turbine Temperature (ITT)—the  temperature of the gases between the high-pressure  and low-pressure turbine wheels.  • Turbine Outlet Temperature (TOT)—like EGT, turbine  outlet temperature is taken aft of the turbine wheel(s). Most jet engine ignition systems consist of two igniter  plugs, which are used during the ground or air starting of  the engine. Once the start is completed, this ignition either  automatically goes off or is turned off, and from this point  on, the combustion in the engine is a continuous process. An engine is sensitive to the flow characteristics of the air  that enters the intake of the engine nacelle. So long as the  flow of air is substantially normal, the engine continues to run  smoothly. However, particularly with rear-mounted engines  that are sometimes in a position to be affected by disturbed  airflow from the wings, there are some abnormal flight  situations that could cause a compressor stall or flameout of  the engine. These abnormal flight conditions would usually  be associated with abrupt pitch changes such as might be  encountered in severe turbulence or a stall. On some jet airplanes, thrust is indicated by an engine pressure  ratio (EPR) gauge. EPR can be thought of as being equivalent  to the manifold pressure on the piston engine. EPR is the  difference between turbine discharge pressure and engine inlet  pressure. It is an indication of what the engine has done with  the raw air scooped in. For instance, an EPR setting of 2.24  means that the discharge pressure relative to the inlet pressure  is 2.24:1. On these airplanes, the EPR gauge is the primary  reference used to establish power settings.  [Figure 15-5] Because of the high altitudes and extremely cold outside air  temperatures in which the jet flies, it is possible to supercool  the jet fuel to the point that the small particles of water  suspended in the fuel can turn to ice crystals and clog the  fuel filters leading to the engine. For this reason, jet engines  are normally equipped with fuel heaters. The fuel heater  may be of the automatic type that constantly maintains the  fuel temperature above freezing, or they may be manually  controlled by the pilot.  In order to avoid the possibility of engine flameout from the  above conditions, or from other conditions that might cause  ingestion problems, such as heavy rain, ice, or possible  bird strike, most jet engines are equipped with a continuous  ignition system. This system can be turned on and used  continuously whenever the need arises. In many jets, as an  added precaution, this system is normally used during takeoffs  and landings. Many jets are also equipped with an automatic  ignition system that operates both igniters whenever the  airplane stall warning or stick shaker is activated. Fuel Heaters Setting Power Jet Engine Ignition Continuous Ignition 15-4