Engine instruments
Tachometer, manifold pressure, oil pressure and temperature, CHT, and EGT: the gauges that tell you what the engine is doing before it tells you by quitting.
12 min read · Flight instruments
After this lesson you can
- Read the tachometer correctly on both fixed-pitch and constant-speed propellers, and explain why they behave differently.
- Apply the manifold-pressure-and-RPM sequencing rule when changing power, and explain why it protects the engine.
- Distinguish oil pressure (direct, immediate) from oil temperature (indirect, delayed), and react correctly to an abnormal reading of each.
- Use the EGT gauge to lean the mixture, and know its limits as a diagnostic tool.
Every instrument covered so far in this module describes the trajectory: where the aircraft is, which way it is pointed, how fast it is moving. The engine instruments describe something different: the health of the machine that keeps all of that possible. Flying without cross-checking them is flying blind to the one system that, if it quits, ends the flight regardless of how well the airplane is being flown.
On a light piston single the panel is minimal by design: a tachometer, a manifold pressure gauge if the engine has a constant-speed propeller or forced induction, oil pressure and temperature, and often a cylinder head or exhaust gas temperature gauge. Each one has a narrow green band for normal operation and a red line for its limit. The real skill is not reading the gauge, it is knowing the normal cruise value for your specific aircraft well enough to notice the moment it drifts.
The rest of this lesson
- 1.The tachometer
- 2.The manifold pressure gauge
- 3.Oil pressure and oil temperature
- 4.Cylinder head temperature (CHT)
- 5.Exhaust gas temperature (EGT) and leaning
- 6.Fuel gauges, and building the scan
These 6 sections, their figures, the checks along the way and the end-of-lesson quiz come with the PPL track. Paid once, yours for good.
Key terms
Try to recall each definition before turning the card.