Engines - Oil Fuel System Flashcards
What does the engine oil system provide?
Lubrication of engine bearings and gearboxes and oil pressure for propeller actuation
What is the oil system pressure?
55 to 65 psi
What does the single system supply oil to?
The reduction gearbox and the turbo machinery
What do the two subsystems do?
The pressure oil system - supplies oil to the engine
The scavenge oil system - returns the used oil to the tank
What pressurises the oil system?
A gear pump driven from the accessory gearbox
Also routes it to an oil cooler
What does the engine network provide oil pressure to?
- fuel heater
- oil low pressure switch
- oil pressure transmitter
- oil temperature sensor and accessory gearbox
- engine bearing cavities
When will the oil low pressure switch illuminate?
When the oil pressure drops below 40 psi
When is the low pressure warning on the CAP inhibited?
For 30 secs during engine start and at all times when the associated condition lever is in fuel shut off
When is the red light on the oil guage inhibited?
When the associated condition lever is in fuel shut off
When will the oil cooler flap open?
If the oil temp is greater than 81 degrees, and the oil will be routed through the oil cooler
The cooler is progressively bypassed as the temperature approaches 71 degrees
What will happen if a clog develops in the oil cooler?
A valve will open to allow oil to bypass the cooler
What does the low oil temperature relief valve do?
Returns the oil to the tank to prevent a pressure surge during cold starting
What does the pressure regulating valve do?
Maintains a constant oil pressure in relation to the air pressure in the cavity
Where is the Fuel Cooled Oil Cooler located?
On the reduction gear box
Where does the oil from the auxiliary tank go?
- To the electrical auxiliary feathering pump
- to the propeller valve module mounted on the reduction gearbox
- to the reduction gear train and bearings
How is oil scavenged from number 1 and 2 bearing cavities?
Scavenged by gravity
How is oil drained from the number 3, 4 and 5 bearing cavities?
Gravity driven and assisted by the air leakage from the bearing labyrinth seals
How is oil drained from the number 6 and 7 bearings?
Scavenged by a pump which is part of the pump pack
How is fuel delivered?
Drawn from the feeder compartment, flows through the fuel heater then delivered under pressure to the HMU
What function does the HMU provide?
- deliver fuel under pressure to the engines, controlled by the metering valve and any excess fuel is returned to the HP pump inlet
- provide the high pressure motive flow required by the fuel tank jet pump
What is the purpose of the fuel-oil cooler?
Oil is used to heat the fuel
