GAUGES
There are a number of gauges that can be fitted to light aircraft not all of them are necessarily fitted to the Piper PA28/140.
FUEL GAUGE:- This gauge is fitted to most, if not all, light aircraft. In fact there are usually two, one for each of the fuel tanks fitted in the main wings.
FUEL PRESSURE GAUGE:- This gauge is normally fitted to aircraft with low wings. On aircraft with high wings such as the Cessna 152/172 the fuel is gravity fed from the wing tanks to the carburettor. Such aircraft are not normally fitted with this gauge. However, on aircraft such as the Piper PA28 140/180, because the wing tanks are below the engine the fuel is pumped up to the carburettor. On such aircraft it is normal to fit a fuel pressure gauge.
OIL TEMPERATURE GAUGE:- Yes you have guessed it, it indicates the engine oil temperature. The green band on the gauge usually indicates normal temperature. Anything out of the green area indicates a potential problem.
OIL PRESSURE GAUGE:- I am sure you can guess this one too, it indicates the oil pressure, an absolute essential requirement if the engine is to continue turning for very long. Once again, the green band on the gauge indicates the correct limits of the oil pressure. Should the gauge indicate outside the green area, it could have serious consequences.
AMMETER:- This gauge is fitted to most light aircraft and indicates the charge/discharge state of the aircraft's battery.
SUCTION:- This gauge indicates the air pressure from the engine driven vacuum pump. Should this pressure drop to zero, then the air driven gyro instruments would shortly fail.