LUBRICATION SYSTEM Flashcards
The primary function of any lubricant is to____________ caused by metal-to-metal contact. Lubricating oils provide a film that permits surfaces to glide over one another with less friction
reduce friction
Liquids are used as lubricants for all internal combustion engines. Liquid lubricants are pumped or______ on bearing surfaces to provide cushioning and to dissipate heat. An essential requirement of the liquid lubricant is that it must remain chemically stable over long periods of time
sprayed
Most aircraft employ a _________ configuration for oil storage. In a dry sump system, the oil supply is carried in a tank located in the airframe or mounted on (but not an integral part of) the engine. With this type of system a larger oil supply can be carried and the temperature of the oil can be readily controlled. The dry sump system allows axial flow engines to retain their comparatively small diameter by arranging the oil tank and oil cooler in a manner consistent with the streamlined design of the engine
dry sump
Three Subsystems of the Dry Sump System:
Pressure subsystem: supplies lubricating oil from the tank to the main engine bearings and the accessory drives.
Scavenge subsystem: removes the oil from the main bearings and accessory drives through the oil coolers and returns it to the tank, completing the oil flow cycle.
Breather pressurizing subsystem: connects the individual bearing compartments and the oil tank with the breather pressurizing valve to help minimize oil leakage
PRESSURE SUBSYSTEMS OF THE DRY SUMB SYSTEM:
Pressure subsystems normally employ an engine driven, gear type, pressure pump. The pump receives oil at its inlet side through gravity flow from the oil tank and discharges oil to a spacers-and-screens type oil filter. From the oil filter, oil is transmitted downstream to the pressure relief valve. The pressure relief valve regulates system pressure and returns unwanted oil to the pump inlet. From the pressure relief valve, the oil is sent via tubing to lubricate the main engine bearings and accessory drive housing. The pressurized oil is sprayed through fixed orifice nozzles, providing a relatively constant oil flow at all engine speeds
The filter bypass valve allows oil to flow around the filter element, should this filter become _______. If this occurs, the filtering action is lost, allowing unfiltered oil to be pumped to the bearings
clogged
When the magnetized contact points collect enough _____________ a circuit is completed between the contacts which illuminates a warning light in the cockpit. The pilot is advised of metal contamination which is an indication of possible failure of one of the engine gears, bearings, or other metal parts
metal particles,
