MLO Flashcards
Purpose
The purpose of the Main Lube Oil system is to provide clean lubricating oil at the correct temperature, viscosity and pressure to the main gearing, clutches, and the combined thrust and plummer blocks for lubrication and cooling. It also serves the seconadry purpose of cooling the oil for the LOSCA.
Caps and Lims
Port: 125 cum
Stbd: 95 cum
1.5 bar
35 - 42 C
Sump Tank
3.78 cum capacity
3.6 cum nominal volume
3.2 cum working volume
0.4 cum circuilating
Provides a reservoir for storing the oil.
Baffled tank reduces aeration.
90s dwell time reduces aeration.
Vented to atmosphere via vent through FER uptakes.
MLO Pumps
Two positive displacement, electric motor driven, screw-type pumps.
Deliver lubricating oil from the sump tank to the distribution manifold.
High: 1800 rpm, 125 cum/h, 4.4 b
Low: 880 rpm. 50 cum/h, 4.4 b
Air turbines: 110 cum/h, 3.3b
HP air flasks
4x HP storage flasks.
Air turbine coupled to an electric motor coupled to the MLO pump.
Drive the pumps during a loss of electrical power and a pressure drop below 1.1 bar.
Relief Valve
Protect the system from over pressurization due to the use of positive displacement pumps.
Set to 4.5 bar with excess oil directed back to the sump.
Cooler
Shell and tube type heat exchanger.
Water in the tubes, oil in the shell.
Controls the temperature of the lubricating oil.
Normal: MSWC
<50 rpm: ASWC 32mm (opened and closed automatically)
<0.5 bar: ASWC 150mm (opened automatically, closed manually)
Cooler is baffled.
Lube oil higher pressure than water.
Has a bypass line.
Temperature Regulating Valve (WCV)
Three-way pneumatically operated temperature regulating valve.
Regulates the temperature of oil.
Some oil goes through cooler, some is bypassed, WCV determines the ratio. Then they mix.
The WCV recieves a temperature measurement of oil after it has passed through the LOSCA to account for heat gained from cooling the GT synthetic oil.
35-42 C
Warning at 50 C
Alarm at 55 C
Fails to full cool with loss of LP air.
Draw the WCV
LOSCA
Lube Oil Storage and Conditioning Assembly.
Is a shell and tube type heat exchanger.
Cools the GT syngthetic lubricating oil.
Oil is sent to the LOSCA by back pressure created via an orifice plate.
Filter Bank
Duplex filters connected by two ganged three-way valves.
Remove particulate from the lube oil.
Only a single filter is used at a time.
Rated to 30 microns absolute, 14 microns nominal.
Warning at 0.6 bar.
Bypass opens at 0.69 bar differential. Dirty oil is better than no oil at all.
Pressure Regulating Valve
Pneumatically operated pressure regulating valve.
Relieves excess pressure over 1.5 bar.
Excess oil directed to sump.
Orifice plate dampens overshoot when sudden changes occur.
Orifice plate only on port system due to larger flow requirements.
Fails closed with loss of LP air.
Combined Thrust and Plummer Bearing
MLO line feeds CTPB.
Tuning valves ensures constant flow rate of 50 L/min.
Line splits to feed fwd and aft sides of thrust block.
Each line passes through orifice plates.
Orifice plates prevent rapid draining of thrust portion of the block in the event of disruption to LO supply pressure.
Oil then exits the top to enter the Plummer Bearing.
Then returns to sump.
Distribution Manifold
Lubricating Oil is directed to gearboxes and cluthches and returns to sump.
Sight glasses
Used to verify oil flow.
Most common one to look at is at discharge side of the CTPB as it is furthest from the pumps.