Turbines 3 Midterm 4

Where is excess fuel not required by the FCU routed?

Back to the inlet of the HP fuel pump

To the fuel tank

To a dedicated overflow reservoir for use during the next engine start

There is never any excess fuel as all of it is required for combustion.

Which fuel system component maintains the selected engine thrust setting?

Speed governor in the FCU

LP (primary) fuel pump

HP (secondary) fuel pump

Pressurization and dump valve

Identify the fuel system component in the picture.

HP fuel filter

Fuel filter differential pressure switch

HP fuel pump assembly

FCU (fuel control unit)

What is the medium used for the fuel heater downstream of the spar valve?

Engine oil

8th stage compressor bleed air

13 stage compressor bleed air

Fan discharge (bypass) air

How many igniters are installed in the JT8 and what is the location on the engine?

1 igniter at the 12:00 position

1 igniter at the 6:00 position

2 igniters, at 2:00 and 10:00

2 igniters, at 4:00 and 7:00

Referencing the illustration, when is 'Continuous Ignition' available once the Continuous Ignition switch is selected on?

When the start switch is in the 'OFF' position

Anytime the 'Continuous Ignition' switch is selected on

When the start switch is in the 'FLIGHT' position

Only when the aircraft is on the ground with the throttle above idle

What is the purpose of the pressure ratio bleed controller?

Used for compressor stall protection

Controls the variable inlet guide vanes

Used for the turbine clearance control system

Minimizes the risk of a tailpipe fire during engine shutdown

What is the primary thrust parameter on the JT8D engine (see picture below)?

Engine Pressure Ratio (EPR)

N2 speed

Oil Pressure

Exhaust Gas Temperature (EGT)

Referencing the diagram, what type of oil system does the JT8D use?

Wet sump

Dry sump, hot tank

Dry sump, cold tank

Integral

How does the oil return to the oil tank (reservoir) on the JT8D engine (see diagram)?

The oil gravity-drains directly from the bearing sumps into the oil tank.

Scavenge pumps deliver the oil from the bearing sumps directly to the oil tank.

A dedicated AGB scavenge pump transfers the oil to the tank after receiving it from all the bearing sumps.

This is a wet sump system, so there is no separate (dedicated) oil tank.

What type of starter does the JT8D engine use?

Air turbine starter

Electric starter

Starter-generator

Hydro-mechanical starter

Which engine parameter is referenced to determine the selection of events during a JT8D engine start (fuel on, starter off, etc.)?

Engine pressure ration (EPR)

N1 speed

N2 speed

Engine oil pressure

Referencing the attached chart, when does the start valve close during a JT8D engine start?

20% N1

20% N2

40% N1

40% N2

Identify the JT8D engine component in the picture (yellow arrow) .

Fuel pump assembly

Oil pump assembly

Accessory gearbox

Reduction gearbox

How is the combustion chamber accessed when carrying out a borescope inspection on the JT8D engine?

Through the front of the engine

Through the back of the engine

Via the individual fuel nozzles

Through the igniter plug ports

What is the purpose of the engine data plate (as referenced for engine trimming)?

It states the engine's performance when the engine was new.

It identifies the engine installation on the aircraft (#1, 2, 3, etc.).

The information provided is used to rig the engine controls, between the throttle quadrant and fuel control unit (static rigging).

The data plate is only used by the records department for tracking purposes.

Which of the following is performed when trimming an engine?

Fuel adjustments are made on the fuel control unit.

The throttle system is rigged between the throttle quadrant and fuel control unit.

The engine mounts are adjusted, through the use of shims (spacers), at the pylon.

The engine is removed and sent to an overhaul shop for hot section calibrations.

What type of combustion chamber is installed in the PT6A engine?

Single can

Multi-can

Can-annular

Reverse flow annular

Choose the answer that describes the compressor arrangement on the PT6A engine.

5 stage axial flow

2 stage centrifugal

Combination compressor

3 stage in-line radial

What is the purpose of the PT6 compressor turbine (CT disk)?

Drives the auxiliary gearbox only

Powers the propeller through the reduction gearbox

Ensures that the propeller tip speed stays below the speed of sound

Drives the compressors and accessory gearbox

Identify the location of Station 2.5 in the PT6 illustration.

Ng compressor inlet

Inter-compressor

Fan bypass

Turbine discharge

What is the gear arrangement of the PT6 reduction gearbox (see picture below)?

Planetary gears

Helical gears

Bevel gears

Spur gears with a sprag clutch mechanism

Identify the component indicated in the adjoining picture of the PT6.

Oil pressure pump

Oil scavenge pump

Fuel control unit

Fuel pump

What is the fuel heater status if the slide valve is positioned on the right side of the chamber (see diagram)?

Full fuel heat is available

The oil is bypassing the cooler to reduce the fuel temperature

The oil is bypassing the cooler to increase the fuel temperature

The fuel is bypassing the cooler to increase the oil temperature

Which component is responsible for maintaining the selected power command in the FCU (see illustration)?

The governor

The bypass valve

Px pressure

High pressure relief valve

Referencing the illustration, which component spins the input shaft (7) in the FCU?

Fuel pump

Oil pump

Reduction gearbox

Compressor discharge vacuum pump

What happens to fuel flow if the Py valve opens (circle & arrow at bottom right corner in diagram below)?

Fuel flow increases (metering valve is driven towards open)

Fuel flow decreases (metering valve is driven towards close)

There is no change in fuel flow, as this is a function of pump output pressure only.

There is no change in fuel flow, as only Px pressure regulates the position of the metering valve.

Identify the component in the accompanying picture (circled with red arrow).

Fuel/oil heat exchanger

Propeller governor

Fuel pump assembly

Power turbine

How is the metering valve positioned in the PT6 FCU (see diagram)?

It is directly controlled by the throttle via mechanical linkage.

It is positioned by the governor bellows via mechanical linkage.

Px and Py pressure act directly on the metering valve to comply with required fuel flow demands.

Only the governor flyweights provide direct input to the metering valve.

What type of fuel system is installed in the PT6?

Hydro-mechanical

Hydro-pneumatic

FADEC

Auto-governing electro-pneumtic

Identify the JT8D fuel system components depicted in the illustration

Pressurization and dump valve

Fuel control unit

Fuel manifold and nozzle assembly

Combustion drain valve assembly

What type of combustion chamber is installed on the Garrett engine shown in the picture?

Reverse flow annular

Single burner (can type)

Can-annular

Tubular

What function is provided by the interconnector in the combustion chamber depicted in the illustration?

Provides a solid support with adjacent combustion cans to reduce engine vibration

Provides an alternative fuel inlet to the combustion chamber for redundancy

Allows cooling air to be distributed evenly between cans

Balance the pressure and provides a flame path between cans during engine starting

When would the spar (main fuel shutoff) valve normally be closed by maintenance personnel (ref. The diagram as desired)?

Whenever there is an upstream fire or overheat, between the fuel tank(s) and the valve

During engine ground run-ups

During a wet cycle to check for fuel flow

When disconnecting a fuel line downstream from the valve

Referencing the diagram, what is the purpose of the second stage fuel pump?

Supplies metered fuel to the FCU (fuel control unit)

Diverts excess fuel flow back to the inlet of the first stage pump, through the pressure relief valve

Sends unmetered high pressure fuel to the FCU

Provides motive flow to scavenge fuel (i.e. Collect fuel) from the fuel tanks

The pressurization and dump valve in the diagram serves to schedule primary and secondary fuel flow to the fuel nozzles. What is its other function?

Adds air to the fuel nozzles for proper atomization in the combustion chamber

Boots the pressure from the engine driven fuel pumps to ensure a positive fuel supply

Provides positive fuel cutoff at engine shutdown and drains fuel from the manifolds

Removes contaminants from the fuel system prior to entering the combustion chamber

Select the type of seals used to keep the oil in the bearing compartment (see diagram)

Labyrinth

Carbon

O-rings

Brush

Which of the following is a function of a pressurization and pump (P & D) valve (ref. Diagram as required)?

Used as the engine-driven fuel pump in a FACED system

Schedules primary and secondary fuel flow to the nozzles

Provides fuel flow to the combustion chamber during shutdown

Shuts off engine fuel supply when the fire handle is pulled

What is the purpose of the fuel heater shown in the diagram?

Cools 13th stage air prior to use for aircraft systems, such as air conditioning and pressurization

Removes contaminants from the fuel to prevent filter clogging

Cools the engine and CSD oil

Prevents the formation of ice crystals in the fuel

What type of igniter plug is depicted in the accompanying picture?

Glow plug

Element igniter

High tension (high energy) igniter

Low tension (low energy) igniter

What effect would placing the rotary switch to ‘IGN RT’ have on ignition system operation for a selected engine (ref. Attached picture)?

The right igniter fires continuously

Both igniters fire continuously

The right igniter is disabled and only the left igniter would operate

It is a function used only by maintenance personnel for ignition testing purposes

When would the flight crew select the ‘AUTO’ position on the ignition switches during operation (see illustration)?

When engine starts have been completed

During the flight for automatic ignition if engine power is lost

Prior to engine starts to heat up the igniter plug

Selected during takeoff, landing and bad weather conditions

What is the name of the ignition system component identified (red arrow) in the picture?

Ignition exciter

Igniter unit

Ignition module

�black box’

Identify the area of the engine that houses the highest potential energy

The outlet of the combustor

The exhaust nozzle

The diffuser section

The inlet to the compressor

Which statement best describes the term cascading?

The pumping action of airflow from high to low pressure zones through the stages of axial flow compressors

The mechanical arrangement of the stators and rotors getting progressively smaller from front to back on axial flow compressors

The installation of fan reverser panels around the circumference of the engine casing, used to redirect airflow during thrust reverse selection

The progressive closing and opening of the variable inlet guide vanes and stators of axial flow compressors as power is increased and decreased

As per the diagram, where does unmetered fuel become metered fuel?

Main fuel shutoff valve (spar valve)

Fuel Control Unit (F.C.U.)

High pressure fuel pump

Low pressure fuel pump

How is Ram Effect (Ram Recovery) achieved on a turbine engine?

By reducing power at higher altitudes

By using a divergent inlet duct design

By using variable inlet guide vanes and stators, as well as compressor bleed valves

Through the use of a chocked exhaust nozzle

What engine systems are designed to minimize the risk of compressor stall or surge?

Variable fan blades and convergent exhaust nozzle

Variable inlet duct and convergent exhaust nozzle

Active clearance control system and variable turbine rotor blades

Variable inlet guide vanes & stators and compressor bleed control valves

Complete the following sentence: The N1 spool of a triple-spool Rolls-Royce Trent engine consists of ….

Low pressure (LP) compressors and LP turbine(s)

High pressure (HP) compressors and HP turbine(s)

Intermediate pressure (IP) compressors and IP turbine(s)

The fan and LP turbine(s)

Why are compressor blades designed with a twist?

This design forms a divergent nozzle to speed up airflow and increase static pressure

To keep the blade tips below the speed of sound

To ensure that the airflow velocity is consistent from blade root to blade tip

To minimize the risk of reverse airflow during a compressor stall

Turbines 3 Midterm 4

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