3-27. Plenum Drain Valve (fig. 3-9)
Removal. Remove tube assembly and remove plenum drain valve and packing from turbine plenum.
Installation. Install replacement drain valve in turbine plenum using new packing. Install valve with arrow
pointing down. Connect tube assembly.
Section VIII. LUBRICATION SYSTEM
The lubrication system provides lubricating oil, under pressure, to cool and lubricate the gears and bearings in the
engine. The lubricating oil is drawn from the oil tank by the oil pump assembly and directed, under pressure through the
oil filter element to the gears and bearings. A safety bypass valve is built into the body of the oil-filter housing to provide
a safety bypass for the oil in the event the filter element becomes clogged. An oil pressure sequencing switch is
actuated by oil pressure to energize the ignition system and fuel solenoid valve when oil pressure is sufficient to
adequately lubricate the gears and bearings during engine start. A low oil pressure switch is incorporated in the
lubrication system to automatically shut down the engine if oil pressure drops below minimum requirements. A scavenge
pump, an integral part of the oil pump assembly, returns the oil and entrained air from the engine through the oil
temperature regulator to the oil tank assembly. A separate scavenge pump mounted on the dual pad gearbox returns oil
from the dual pad gearbox. The entrained air is vented from the oil tank to the turbine exhaust.
Access to lubrication system -component is obtained by removing fuel and oil components
access panel (fig. 1-1) and gas turbine engine power plant access panel (fig. 1-2).
3-29. Tube Assemblies, Hose Assemblies, Ducts and Plumbing Fittings
Removal. Remove tube assemblies, hose assemblies, clamps, ducts, and plumbing fittings as Required for
acces 'to other components or to replace damaged parts.
Tag or otherwise identify connection points, routing, orientation of fittings, and location of
supporting clamps for aid at assembly.
Cleaning and Inspection.
Clean tube assemblies, hose assemblies, clamps, and plumbing fittings with an approved cleaning solvent
and dry thoroughly with filtered compressed air. Clean ducts with compressed air or a clean rag moistened with an
approved cleaning solvent.
Visually inspect tube assemblies for cracks, corrosion, abrasion, damaged threads, or other evidence of
damage. Inspect ducts for tears, abrasions, and separation of laminations. Replace all damaged parts.
Installation. Install tube assemblies, hose assemblies, clamps, ducts and plumbing fittings in reverse order of
removal procedures using new packings and gaskets as applicable.
Be sure tube and hose assemblies do not make direct .physical contact with other surfaces of
the power unit. Use clamps to support -tube and hose assemblies and prevent contact. The
high frequency vibration of the power unit may cause rapid wear and damage to the tube and
how assemblies leading to failure of the parts.
3-30. Oil Filter Element (fig. 3-12)
Removal. Unscrew filter case from oil pump assembly without removing pump assembly from engine; remove
packing and filter element.
Cleaning and Inspection.
Clean filter case with an approved cleaning solvent and dry thoroughly with filtered compressed air.
Visually inspect filter case for cracks, corrosion, damaged threads or other obvious damage. Replace
damaged filter case.
Installation. Dip new replacement filter element in oil of the same specification and brand being used in engine
lubrication system. Install small packing included with filter element in place, inside filter element neck. Install element
in filter case using new packing. Install assembled filter case in oil pump assembly.