Engine instruments: tach, MAP, CHT, EGT, fuel pressure
Five engine gauges:
| Gauge | Reads | Markings |
|---|---|---|
| Tachometer | Engine and propeller RPM (crankshaft rotation speed) | Green arc = maximum continuous operating RPM. Extra marks for engine or propeller limits |
| Manifold pressure (MAP) | Absolute pressure of the fuel-air mixture in the intake manifold | Green arc = normal operating range. Red radial line = upper limit |
| Cylinder-head temperature (CHT) | Cylinder temperature: direct and immediate | Green arc = normal range. Red line = maximum allowable CHT |
| Exhaust gas temperature (EGT) | Exhaust manifold gas temperature. Varies with the ratio of fuel to air entering the cylinders | None given |
| Fuel pressure | Pressure in the fuel lines | Normal pressure in the AFM/POH or colour-coded on the gauge |
- High CHT cure: increase airspeed or reduce power.
- Cowl flaps: hinged covers over the opening where hot air leaves.
- Open: more airflow, cooler.
- Closed: airflow restricted, warmer.
- EGT: basis for regulating the fuel-air mixture. Leaning by EGT can reduce fuel consumption. Follow manufacturer's leaning procedure.
- Fuel pressure gauge: fitted only if the fuel system has a fuel pump.
Trap: reading EGT as cylinder heat. EGT tracks fuel-air ratio; CHT is the direct, immediate cylinder-temperature gauge.
References
- TP 1102 Ex.2 Aircraft Familiarization, Engine Instruments
- FAA-H-8083-25 PHAK ch.7 (Powerplant, Fuel Systems)