Four support systems keep the gas turbine alive: the oil that serves its few but precious bearings, the gearbox that farms its shaft power out to accessories, the ignition that lights it, and the starter that spins it fast enough to light at all. This lesson takes them in turn, ending with the choreography of an actual start.
Lubrication, turbine style
The tasks of a turbine lubrication system read like the piston module's list, lubricate, cool, clean and protect, but concentrated: a turbine has no cylinder walls or piston rings, so almost the whole oil supply serves the shaft bearings and gearbox, and cooling those few, fast, hot places is as important as slicking them. The components:
Oil tank with centrifugal breather — the tank carries the supply; the breather spins the vented air so its entrained oil mist is flung back to the tank instead of overboard.
Pressure and scavenge pumps — the dry-sump pair the piston module taught: pressure feeds the bearings, larger-capacity scavenge pumps drain each sump.
Filters with bypass — clean the oil, and pass it unfiltered rather than not at all if an element clogs.
Oil sumps — the sealed chambers around each bearing group where oil is applied and collected.
Chip detectors — magnetic plugs in the scavenge lines that catch ferrous debris: a bearing announces its dying in metal particles long before it announces it any other way, and on many aircraft the detector reports to the cockpit or maintenance system.
Coolers — classically fuel-cooled oil coolers (fuel-oil heat exchangers), each a heat exchanger that chills the oil against the fuel flow, warming the fuel (an anti-icing bonus) while cooling the oil.