Lubrication and Oils Flashcards
What is lubrication?
Must for a barrier between moving parts thus reducing friction and wear.
What does lubrication provide?
Impact cushioning Cooling (carries heat away) Cleaning (carriers particles away from filters) Corrosion protection Act as Hydraulic fluid
Where are oil tanks constructed?
Oil tanks can be mounted on the engine or an integral part within the gearbox
Explain the function of an oil tank?
It stores an appropriate quantity of oil to ensure that the engine always has an adequate supply of oil under all operating conditions and attitudes.
Must provide for lubrication draining and replenishment and identification.
10% of oil expansion space must be provided. (expansion space cannot be comprised by oil filling).
What is the requirement of the oils?
Low Volatility Anti Foaming quality Low Lacquer and coke deposits High flashpoint Low pour point Film strength Wide temperature range High viscosity Index
What is the purpose of oil pumps? and what types of oil pumps are there?
Pumps are used to maintain oil pressure within the oil system, they also return oil from the sump/bearing chambers.
Gear, Vane and Geroter type
What is the oil used in gas turbine lubricating systems?
Synthetic anti freeze oil
Explain the fuel cooled oil?
Has a matrix divided into sections by baffle plates that allow oil to pass across tubes so heat is transferred from the oil to the fuel?
Bypasses are installed in the event of a blockage in the cooler.
Explain magnetic plug and chip detectors?
They are fitted on the return side of the oil system and collect any ferrous debris which returns oil may be carrying.
The magnetic plug is a permanent magnet inserted in the oil flow to collect any debris.
Chip detectors are magnetic plugs that incorporate chip detectors that can transmit signals to the cockpit in the case of sufficient build-up.
Explain the purpose of oil filters?
To prevent foreign matter from continuously circulating throughout the system. Typically fitted at the tank exit
Purpose of relief valves and check valves in the oil system?
To prevent over-pressurization of the system and or its components while check valves prevent backflow
What is the purpose of the internal air system?
Internal engine cooling Accessory Cooling Bearing and chamber sealing Prevention of gas ingestion Control of bearing axial loads Control of turbine blade tip clearance Engine anti icing A/C customer services
Explain cooling in the combustion chamber?
Air flows along the flame tube to lower gas temperature in the dilution zone. There is a need for this as the gasses released will be too hot for entry to the NGV
Explain turbine cooling?
Cooling air is drawn from the high-pressure compressor and ducted through over the blades, disc, and nozzle guide vanes to help with maintaining high thermal efficiency because it allows the blades to operate above melting points with sufficient constant cooling.
How can air benefit seal?
It prevents leakages as high-pressure air is routed to one side of a labyrinth seal and prevent bearing cavities from losing oil
