ATPL GROUND TRAINING SERIES — Page 512, Lesson 603

We're starting a brand-new chapter now — Chapter 38, Engine Instrumentation. This is where we move from the flight instruments, which tell you about the aircraft's attitude and position, into the powerplant and systems monitoring side of the cockpit. And I want to make one thing clear right at the outset: just as you couldn't fly a large modern aircraft safely without the flight instruments, you also couldn't fly it safely without the engine and aircraft systems instruments. They are not optional extras — they are a fundamental part of your situational awareness as a pilot. So let's begin with the big picture. The engine instruments are divided basically into two categories: Performance Indicators and Engine Condition Indicators. That's the first distinction I want you to lock in, because it shapes how you read every gauge on that panel. Performance Indicators are the thrust-indicating instruments. These are the ones that tell you, directly, how much thrust the engine is producing. The two classic examples are the Engine Pressure Ratio gauge — which we call EPR — and the Fan Speed gauge, which is N1. EPR is a ratio of pressures, and N1 is the rotational speed of the fan. Both of them are your primary way of setting and monitoring thrust. Now, the second category is Engine Condition Indicators. These don't tell you thrust directly — they tell you about the health and operating state of the engine itself. The examples here include the Exhaust Gas Temperature gauge, which is EGT, the Compressor Speed, the Oil Pressure gauge, and the Oil Temperature gauge. So you can see the pattern: performance indicators answer "how much thrust am I getting?", while condition indicators answer "is the engine healthy while producing it?" We're going to discuss all of these and more in the text that follows. And I want you to picture Figure 38.1, which shows some of the parameters I've just mentioned, along with the positions of the sensors that are required to measure them. That's a key point — every one of these gauges is fed by a sensor located somewhere in or on the engine, and understanding where those sensors sit helps you understand what the reading actually means. So as we go through this chapter, we'll cover the types of display, then thrust and power measuring instruments, engine torque, engine rpm, temperature sensing equipment, pressure gauges, engine vibration, the fuel gauge, the remote signal transmission system, and finally the flight hour meter. That's the roadmap. Let's start with the introduction we've just laid down, and then we'll move into the types of display.