GTS Mod 3

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Questions and Answers

What is the purpose of a chip detector in an aircraft lubrication system?

To monitor fuel flow

To measure oil pressure

To collect ferrous debris from scavenged oil (correct)

To regulate temperature in the oil system

How do chip detectors indicate the presence of ferrous material in the oil?

By emitting a visual warning signal

By releasing a scented alert

By bridging an open electrical circuit (correct)

By generating a high-pitched sound

Where can temperature transmitters be located based on the design of the system?

In the oil supply or scavenge line (correct)

In the control tower

In the fuel tank

In the landing gear

What does completing an electrical circuit in a chip detector trigger?

A warning light in the cockpit Signup and view all the answers

In Figure 26, what type of transmitter and indicator is shown?

Temperature transmitter Signup and view all the answers

Where are chip detectors typically located within an aircraft lubrication system?

In the oil flow with ferrous material Signup and view all the answers

How does a cyclonic breather operate?

By directing oil-laden air into the separator cylinder at an angle to create a cyclonic flow pattern Signup and view all the answers

What happens to the oil in a cyclonic breather?

Forced to the sides of the housing and settles at the bottom of the separator cylinder Signup and view all the answers

What allows oil to drain to a sump in a cyclonic breather?

Drain holes at the bottom of the separator cylinder Signup and view all the answers

How do oil temperature transmitters work?

Sensing oil temperature and transmitting a signal to an indicator Signup and view all the answers

What changes as oil temperature changes in an oil temperature transmitter?

The electrical resistance of the transmitter Signup and view all the answers

What is the primary purpose of the oil cooler flap thermostat?

Regulate oil flow through the air cooled oil cooler Signup and view all the answers

Where is the oil cooler flap thermostat located?

Downstream of the oil cooler Signup and view all the answers

What does manual operation of the oil cooler flap allow for?

Adjust airflow by moving the flap open or closed Signup and view all the answers

In what circumstances can the oil cooler flap be manually driven towards closed?

To close off airflow Signup and view all the answers

Which component is responsible for sensing oil temperature leaving the cooler?

Oil cooler thermostat Signup and view all the answers

What is the purpose of moving the flap actuator by the oil cooler thermostat?

To maintain correct airflow Signup and view all the answers

What happens as the drive gear rotates and pulls the driven gear around in a gerotor pump?

The expanding cavity is under the inlet port and fluid is drawn in Signup and view all the answers

What is the primary function of a metering pump in an aircraft lubrication system?

To supply a metered amount of oil to bearings Signup and view all the answers

What role do gerotor pumps play in oil systems on aircraft?

Keeping oil consumption at a required level Signup and view all the answers

What distinguishes metering pumps from other types of pumps in aircraft lubrication systems?

They supply a specific and controlled amount of oil Signup and view all the answers

Where are metering pumps commonly utilized in aircraft systems?

Turbine and compressor shaft bearings Signup and view all the answers

What is the function of the gears in gear pumps for aircraft lubrication systems?

To draw oil into the pump and deliver it to the outlet side Signup and view all the answers

What is the purpose of the bronze bushes in gear pumps used in aircraft lubrication systems?

To reduce friction between the gears and the housing Signup and view all the answers

Which part of a gear pump in an aircraft lubrication system has a relief slot machined in it to prevent hydraulic locking?

End of each tooth Signup and view all the answers

What is the significant advantage of using gear pumps in aircraft lubrication systems?

Constant oil flow regardless of engine speed Signup and view all the answers

What distinguishes the gerotor pump type from other delivery pump types in aircraft lubrication systems?

It has a variable displacement design Signup and view all the answers

What is the main difference between a vane pump and a gerotor pump?

Gerotor pumps force oil out of the pump as the space near the inlet diminishes. Signup and view all the answers

Which component distinguishes a gerotor pump from a vane pump?

Lobe shaped gear Signup and view all the answers

How does a gerotor pump differ from a vane pump in terms of operation?

A gerotor pump rotates freely in the housing, while a vane pump has an eccentric rotor. Signup and view all the answers

Why are vane pumps considered to be lighter than gear and gerotor type pumps?

Gear and gerotor pumps are heavier due to additional components. Signup and view all the answers

What is the primary function of a gear pump within an aircraft lubrication system?

Receiving oil from the oil tank for distribution through the lubrication system Signup and view all the answers

In a gear pump assembly containing both delivery and scavenge elements, why is the scavenge element typically larger?

To handle the hotter return oil coming from main bearings Signup and view all the answers

Which component usually provides oil supply to the delivery element in a gear pump?

Oil tank Signup and view all the answers

What distinguishes the driven gears in a duplex gear pump assembly?

They are located on separate shafts Signup and view all the answers

How do gear pumps differ from other types of pumps typically used in aircraft systems?

Gear pumps have separate compartments for delivery and scavenge elements Signup and view all the answers

What fills the space between the opposing piston and metering pin in the metering pump?

Oil from the delivery pump Signup and view all the answers

How does the movement of the cam against the pumping piston affect the inlet port?

It covers the inlet port periodically Signup and view all the answers

Why are scavenge pumps larger in capacity compared to pressure pumps?

To accommodate heat expansion and aeration Signup and view all the answers

What assists in moving scavenge oil from some parts of engines in the lubrication system?

Bearing cavity pressure Signup and view all the answers

What do engine oil system filters primarily remove from the lubrication system?

Contaminants Signup and view all the answers

What is the purpose of the double-element gear pump in the power section oil pump?

To regulate oil pressure at 55+/-5 PSI Signup and view all the answers

What is the function of the adjustable pressure regulating valve in the power section oil pump?

To prevent excessive back-pressure at the pump outlet Signup and view all the answers

What does the bypass valve on the power section oil pump allow for?

Prevention of excessive back-pressure at the pump outlet Signup and view all the answers

When does the check valve within the system operate in relation to pressure?

Within a range of 6–10 PSI Signup and view all the answers

Where does oil enter after passing through the filter assembly in the delivery oil flow path?

Into annular ring formed by air inlet housing and compressor extension shaft housing Signup and view all the answers

Where is the oil picked up by the second element of the pump?

From the sump in the inner combustion casing liner Signup and view all the answers

What does the accessory gearbox in the context of gear pumps mainly function as?

A sump for the entire engine system Signup and view all the answers

Which component of the powerplant serves as a breather system's main vent to atmosphere?

Torquemeter assembly Signup and view all the answers

What is the primary function of the main scavenge pump in the engine system?

To scavenge oil from various components like compressor extension shaft and front bearing Signup and view all the answers

Where is the power section breather mounted within the powerplant?

On top of the air inlet housing Signup and view all the answers

What is the pathway for oil draining from the compressor front bearing to reach the accessory gearbox?

Through a tube that ports oil out through the bottom vertical strut into the accessory gearbox Signup and view all the answers

What is the function of a breather system with respect to an engine's oil system?

To vent air from the oil system to atmosphere Signup and view all the answers

What is the role of the air inlet housing in relation to oil drainage within the engine system?

To enable drainage through vertical struts into the accessory gearbox Signup and view all the answers

Which component of an aircraft engine system primarily acts as a lubricant carrier?

Main Scavenge Pump Signup and view all the answers

How does an accessory gearbox contribute to maintaining proper lubrication within an engine system?

By serving as a sump and lubricating various drive shaft bearings Signup and view all the answers

Study Notes

Lubrication System Components

Temperature transmitters:
- Located in oil supply or scavenge line
- Sense oil temperature and transmit signal to cockpit indicator
- Change in current flow corresponds to temperature change
Chip detectors and magnetic plugs:
- Installed in lubrication system to collect ferrous debris from scavenged oil
- Enable early identification of engine internal failure
- Chip detectors are permanent magnets that protrude into oil flow and collect ferrous material
- Bridging of electrical circuit by metal chips triggers cockpit indication

Breathers

Centrifugal breather:
- Uses air/oil mist entry holes to separate oil from air
- Oil is forced to sides of housing and settles at bottom of separator cylinder
- Drain holes at bottom of separator cylinder allow oil to drain to sump
Cyclonic breather:
- Directs oil-laden air into separator cylinder at an angle to create cyclonic flow pattern
- Swirling pattern creates separation of oil from air
- Oil is forced to sides of cyclonic breather housing and settles at bottom of separator cylinder

Pumps

Metering pump:
- Supplies metered or regulated amount of oil to bearings on turbine and compressor shafts
- Used in partial and total loss oil systems
- Ensures oil consumption is kept to required level while supplying adequate oil to bearings
Delivery oil pump:
- Driven by engine and usually located on accessory drive gearbox
- Supplies oil to parts of engine that require lubrication
- Types: gear, vane, gerotor, and metering
Scavenge pump:
- Returns oil from lubrication points to oil tank
- Passages that scavenge oil follows vary between engines; typically include filtration, cooling, and de-aeration
- Bearing cavity pressure assists movement of scavenge oil from some parts of engines

Gear Pumps

Consist of two steel gears with one driven by engine or power supply
Other gear meshes with and is driven by drive gear
Bronze bushes enclosed in closely fitted housing support each gear
Oil is drawn into pump and carried round between teeth and case, and delivered to outlet side of pump

Vane Pumps

Consist of rotor drive-shaft, eccentric rotor, sliding vanes, and pump housing
Space between vanes and case fills with oil as it passes inlet
Oil is carried towards outlet and forced out of pump as space near outlet diminishes
More tolerant of oil-borne debris than other types of pumps and lighter than gear and gerotor type pumps

Gerotor Pumps

Use similar principle to vane pump
Consist of lobe-shaped gear, rotor, and pump housing
Gear rides inside rotor, which rotates freely within housing
Multi-tooth eccentric spur drive gear is turned by accessory drive from engine
Rotates multi-tooth internal gear rotor as it turns

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Description

Test your knowledge on aircraft temperature transmitters and indicators. Learn about the locations where temperature transmitters can be found in an aircraft's oil supply or scavenge line.