15.10 Flashcards
What does the lubrication system do
Distribute oil to the engine bearing compartments and gearboxes
Where does wet sump store oil
In the engine
Where is dry sump oil store oil
External supply tank mounted on a engine or near the engine
2 types of oil/lubrication systems
Full flow and constant pressure
Why is the full flow the simplest type of oil supply system
It has no way of regulating oil pressure
In full flow what happens to the oil pressure if the rotor speed increases
Higher oil flow which leads to higher oil pressure
What happens to oil pressure if temperature increases
Lower viscosity which leads to lower resistance which gives lower oil pressure
What does the pressure relief valve do
Prevent oil pressure becoming too high
What 2 sides is a pressure relief valve installed
Delivery side and suction side
What is constant pressure system also called
Regulated pressure system
In a constant pressure system does oil temperature affect oil pressure
No
Most common oil system
Full flow due to simplicity and no adjustments needed during maintenance
Disadvantages of full flow system
- Large supply pump or oil pressure
- Oil temperatures rise when power reduces
Why is the exhaust turbine bearing critical lubricating point
Due to high temperatures
What does oil for bearing cooling require
Oil cooler
Oil system 3 sub systems
Storage
Distribution
Indicating
What property does silicon give the oil tank
Fire resistance
What are ways to fill the oil tank
Gravity and pressure fill
What does a scupper do
Catches oil spilled during service and drains it to engine drain mast
What does a check valve do
Prevents discharge of air and oil through the filler when not correctly fitted
What are the 2 oil pumps
Gear (most used)
Gerotor
Gear type oil pump elements
One for pressure oil
One for scavenging
What’s the difference between gear pump and gerartor pump
Size of elements can be controlled by varying size of gerotor elements
What does a bypass valve do
Maintain oil temperature or pressure by varying proportion of total oil flow passing through the oil cooler or filter
In a lubrication system where is the screens/last chance filters installed
Supply lines upstream of the oil nozzles
What is a hot tank system
Oil cooler installed in the supply line , oil is not cooled before it returns to the tank
What is a cold tank system
Oil cooler installed in the scavenge line system , oil from bearing compartment is cooled before returning to the tank
Where are fuel cooled oil coolers used
Jet engines because small and efficient
Where are air cooled oil coolers used
Engines or APU
How many scavenge pumps does the oil pump
7
What does a breather do
Removed air from scavenged oil
What does a de-aerator do
Installed at the inlet for scavenge oil
Separates air from incoming scavenge oil
How long should you leave the filler cap in after shut down
5 minutes or hot oil can spit out
Two types of transmitters used
Capacitance and reed switch
What size particles can the scavange oil filter catch
Larger particles more then 0.015mm
Problem with scavange oil filter element
Not changed often and filter inspection takes long
What size particles can the soap program find
0.001mm to 0.02mm
How does a magnetic chip detector work
2 magnets in the tip and resistance decreases when particles connect with the magnets
On engines without an anti-siphon valve when should check oil quantity
Between 5 and 20 minutes after engine shutdown
What does fuel smell when opening fuel cap indicate
Leakage in the fuel cooler oil cooler and troubleshooting is required
Pressure filling is with a what system
Oil servicing system
What is gravity filling done by
Oil cans
Oil flow system
Oil tank - pump - pressure filter housing - pressure oil filer - air oil heat exchanger - fuel cooler oil cooler
