Aircraft Jet Engines oil system

1
Lubrication Systems
2
Table of Contents

1. Introduction
2. Wet Sump System
3. Dry Sump
4. Oil Tanks
5. Oil Pumps
6. Oil Filters
7. Bearing Chamber (may be deleted)
8. Oil System Valves
9. Other Oil Components
10. Spectrometric Oil Analysis Program (SOAP)
11. Trouble Shooting Maintenance

3
1- Introduction

• The primary function of a lubrication system is
  to provide oil to the various parts of the engine
  which are subject to friction loads from engine
  rotation and heat loads from the gas path.
• The lubrication system can be divided into two
  sections
• The Pressure side
• The Scavenge side.

4

• There are two basic classifications of gas
  turbine lubrication systems
• Wet Sump
• Dry Sump

5
2-Wet Sump System

• A wet sump lubrication system was used on early
  gas turbine engines and is now more often found
  on smaller engines or APU's.
• A wet sump system is a lubrication system where
  the oil supply is carried within the engine
  itself or accessory gearbox.
• Pressurized oil is used to lubricate the main
  engine bearings but the accessory gearbox is
  splash lubricated by oil carried in the gearbox
  housing that also acts as a oil reservoir

6
(No Transcript)
7
3-Dry Sump

• A dry sump lubrication system carries its oil
  supply in a tank separate from the engine.
• This now the most common type of lubrication
  system in modern gas turbine engines.

8
Dry sump cont

• Dry sump lubrication systems are divided into two
  categories
• hot-tank system and
• the cold-tank systems.

9
-Hot-Tank Lubrication System

• Has the oil cooler placed in the pressure side of
  the system, and the oil is returned 'hot' to the
  oil tank.
• An advantage of this type of system is that a
  maximum heat exchange occurs because the oil has
  less entrained air in the pressure side of the
  system and this allows a smaller oil-cooler to be
  used.

10
Cold-Tank Lubrication System

• A cold tank system is essentially the same as the
  hot-tank system except that the oil cooler is
  located in the scavenge side of the lubrication
  system and the oil is cooled before being
  returned to the oil tank.
• In engines that have higher oil temperatures
  this is an advantage, as high oil temperatures
  affect oil service life.

11
5-Oil Tanks

• A gas turbine engine oil reservoir is usually
  mounted on the engine or nearby airframe.
• They are usually constructed of aluminum or
  stainless steel and are designed to provide a
  constant supply of oil to the lubrication system.
  

12
Oil tanks cont

• Federal Aviation Regulations (FAR's) require that
  the tanks have an oil tight filler cap and an
  expansion space of 10.
• The expansion space is to make allowance for an
  increase in oil volume due to thermal expansion
  and entrapped air when the engine is operating.
• Most tanks are pressurized to approximately 4
  psi, this has two purposes
• Positive flow of oil
• Suppresses foaming and pump cavitations.

13
Oil tanks cont

• The tanks can contain
• A venting system
• Filler cap and strainer
• De-aerator to remove air
• Oil pick up
• Dip stick
• Sight gauge
• Oil quantity transmitter

14
Oil Pumps

• Vane PumpVane pumps are a constant displacement
  pump more often found in the scavenge side of the
  lubrication system as they are more tolerant of
  debris and have a high volume and relatively low
  pressure.

15
(No Transcript)
16

• Gerotor PumpGerotor pumps are a constant
  displacement pump and are used in both the
  pressure side and the scavenge side of the
  engine.

17
(No Transcript)
18
Oil pumps cont

• Gear PumpGear pumps are the most commonly used
  constant displacement pump and can be found in
  the either the scavenge side or the pressure
  side.

19
(No Transcript)
20
6- Oil Filters

• It is extremely important that the oil used in a
  gas turbine engine is free from foreign particles
  as these particles can cause severe bearing
  damage.
• To keep the oil clean filters are used as the oil
  leaves the pressure pump and again in what are
  called the 'last chance' filters just before the
  oil is sprayed from the oil jet nozzle.There
  are three common types of filter used in gas
  turbine engines

21
Woven Wire Mesh Filter

• Easy to clean, but can generally only remove
  particles larger than 40 microns.

22
Disk-type / Wafer Type Filter

• Made up of a series of screen type filters with
  spacers in between each screen to form a chamber
  which is ported to the central collection tube.
• This type of filter is easily cleaned and
  provides better filtration than a wire mesh
  filter.

23
(No Transcript)
24
Pleated Fiber Filter

• Can remove particles as small as 15 microns. Can
  be cleanable or disposable

25
Bearing Chambers
26
(No Transcript)
27
8-Oil System Valves

• Relief Valve
• Relief valves are designed to maintain a constant
  pressure in the lubrication system and prevent
  over pressurization and damage.
• The relief valves are situated on the discharge
  side of the pump, when the oil pressure exceeds
  the valve setting the valve opens and ports oil
  to the inlet side of the pump.
• Some valve pressure settings can be adjusted by a
  screw.

28
(No Transcript)
29
Bypass valves

• normally found in oil system components and are
  designed to allow oil to bypass a component
  should the component fail and oil is prevented
  flowing through it.

30
(No Transcript)
31
Check Valve

• A one-way valve that ensures that oil flows in
  one direction only

32
9-Other Oil Components

• Chip Detectors
• Magnetic chip detectors are installed in scavenge
  side of the lubrication system
• used to determine the level of metallic wear
  occurring in the engine.
• Some chip detectors are easily removed for visual
  inspections while other may include an electrical
  circuit that illuminates a warning light in the
  flight deck when enough metal chips have
  accumulated to close the gap in the detector.

33
(No Transcript)
34
Heat exchanger

• The oil in a gas turbine engine gathers a great
  deal of heat from the main bearings and this heat
  maybe transferred to either fuel or air.
• Most modern gas turbine engines transfer the heat
  to the fuel to prevent the formation of ice
  crystals.

35
(No Transcript)
36
Air-Oil Separator

• The oil that is picked up by the scavenge pump
  contains a lot of air.
• Oil tanks contain dwell chambers which allow the
  air to separate and the air-free oil to enter the
  tank.
• Some engines also utilize a gear driven
  centrifugal air-oil separator.
• As oil laden air enters the rotating slinger
  chamber, centrifugal action throws the oil
  outwards to collect on the walls and drain down
  into the tank

37
(No Transcript)
38
Breather system

• The breather system is used to keep the air in
  the oil tank at the same pressure as the air in
  the bearing housing.
• This ensures that there is a positive flow of oil
  to the inlet of the main pump and prevents
  cavitations.

39

• After lubricating the bearing the oil drains down
  into the sump and is collected by the scavenge
  pump and returned to the oil tank.
• The scavenge pump not only collects all the oil,
  but also collects some air as well.
• This air is transferred to the tank and is
  separated from the oil by the deaerator and is
  used to pressurize the tank.
• The bearing chamber is vented to the oil tank by
  the vent line and a check valve.
• The oil tank is also vented to ambient air
  through the pressurizing valve which maintains
  the tank at approximately 3-4 psi.
• If the scavenge pump lowers the pressure in the
  bearing chamber, the vacuum valve opens and
  allows air to enter the chamber

40
(No Transcript)
41
10-Spectrometric Oil Analysis Program (SOAP)

• Oil sampling should be done at regular intervals
  just after an engine has been run.
• The contaminants in the oil provide an indication
  of engine wear.

42

• Oil samples taken are passed through a
  spectrometer which precisely burns the oil and
  measures the wavelength of the emitted light to
  determine the type and quantity of contaminates
  in the oil.
• The spectrometer can detect contaminants at 2-3
  parts per million of oil

43

• The contents of the filters can be examined for
  evidence of metal particles, but by the time
  particles large enough to be visible are
  discovered serious engine damage has already
  occurred

44
(No Transcript)
45
(No Transcript)