777 Neptune Groundschool Instruments & Gauges

Oil Pressure Gauge The Oil Pressure Gauge indicates the oil pressure supplied by the oil pump to lubricate the engine Located on the instrument panel Units are pounds (lbs) per square inch (PSI) High oil pressure indicates the oil is viscous (flowing sluggishly) Common in cold temperatures If too high oil could be forced into the combustion camber Low oil pressure indicates oil is not viscous enough Over heating or possibly a leak

Oil Pressure

Oil Temperature Gauge The Oil Temperature Gauge indicates the oil temperature in Fahrenheit or Celsius Located next to the pressure gauge on the instrument panel Strict relationship between oil temperature and pressure High pressure is usually coupled with low temperatures Oil within its normal temperature operating range will show normal pressure Pressure and temperature should change with each other, uncoupled changes (temperature lowering without pressure rising) usually indicates something undesirable

Oil Temperature

Cylinder Head Temperature The Cylinder Head Temperature Guage records the temperature of one (or more) engine cylinder heads Indicates how effective the engine is being cooled Should be monitored during frequent steep climbs High engine temperatures may result in detonation, preignition and, eventually engine failure Lean and Rich settings observe different temerpatures

Cylinder Head Temperature

Tachometer The Tachometer indicates the speed in which the crankshaft is turning in hundreds of revolutions per minute Units are RPM (rotations per minute) in reference to rotations of the axil via the engine Also keeps an accurate record of engine hours (hobbs time) 4 arcs Green – normal operating range Yellow – caution range Red – maximum allowable

Tachometer

Manifold Pressure The Manifold Pressure Gage indicates the presuure of the fuel / air mixture in the engine intake manifold (between the carburetor and cylinders) Units are in inches of Hg When the engine is not running the manifold pressure gage will indicate the sea level pressure A drop in the manifold pressure gauge may be an indication of carburetor icing

Manifold Pressure

Intake manifold