Turbines 3 Midterm 3

What action would normally be taken if an air turbine start valve failed to open during an engine start procedure?
The engine cannot be started and the start valve would need to be replaced.
The manual override on the engine start valve would be operated.
The engine would require hand-cranking at the accessory gearbox.
An alternate start valve would be used at the engine pylon.
Choose the source that is NOT used to provide pneumatics for engine starts from the following:
Auxiliary power unit (APU)
Ground unit (jet start)
Another engine on the same aircraft
Cabin air
What ATA chapter is engine starting?
73
74
76
80
Where is the starter physically located on a turbine engine?
The fan case
The high pressure compressor case
The accessory gearbox
The internal gearbox
What are the consequences of a pneumatic starter not engaging when an engine start is initiated?
The starter must be replaced.
A manual override can be selected on the starter itself.
A manual override can be selected on the start valve.
The start valve must be replaced.
You have just selected 'start' on a double-spool turbofan engine and confirmed that the start valve has opened. What is the first engine parameter that you would observe to confirm starter engagement?
N1 rotation
N2 rotation
Exhaust gas temperature (EGT)
Oil pressure rising
What type of starter does a large aircraft engine most commonly use?
Electric
Hydraulic
Pneumatic
Fuel-powered generator starter
Identify a common inspection item on a starter-generator.
Brush wear
Impeller condition
Start valve operation (located upstream from the starter)
Igniter plug condition
Which scenario could cause an engine tailpipe fire to occur during an engine shutdown procedure?
The fire handle was inadvertently pulled.
The fuel tank boost pump was not shut off.
The variable inlet guide vanes were stuck in the high power operating position.
The combustion drain valve was stuck in the closed position.
What is the power supply source for the electronic control unit of a FADEC fuel system when the engine is running?
A dedicated alternator (generator) on the accessory gearbox
The onside engine generator
The aircraft supplies power to the electronic control unit at all times.
The auxiliary power unit (APU)
Which type of magnetic chip detector burns away small amounts of debris gathered on the detector?
Heated chip detector
Ferro-magnetic chip detector
Pulse chip detector
Radiant-type chip detector
What does ‘high viscosity’ mean when discussing engine oil systems?
The oil is designed for use at high altitudes.
The oil is very thin.
The oil has the same thickness as water.
The oil is very thick.
Where are engine oil magnetic chip detectors commonly installed?
In the oil tank
In the oil scavenge lines
In the oil pressure lines
On the housing of the centrifugal breather
What is the ATA chapter for engine oil?
73
74
79
80
How are main engine shaft bearings numbered?
From front to back
From back to front
Random numbering determined by the engineers
Bearings are generally designated by letter codes
What are the consequences of a gearbox component (ex. Hydraulic pump) seizing during engine operation?
The clutch breakout mechanism would operate to disconnect the input drive.
The input shear shaft would break.
The circuit breaker will open and cannot be reset as long as the condition exists.
The engine would have to be shut down to avoid seizing.
What is the most common gear arrangement for the internal gearbox on contemporary turbine powered engines?
Bevel gears
Worm gears
Spur gears
Planetary gears
Which part of the engine drives the internal gearbox on a multi-spool engine?
Low pressure spool
Intermediate pressure spool
Fan assembly
High pressure spool
What is a common name for the drive shaft installed between the internal gearbox and accessory gearbox?
Radial drive shaft
Accessory drive shaft
Internal drive shaft
Rotary transfer shaft
Which of the following would most likely cause a compressor stall?
A reduction in axial airflow and increase in rotational airspeed in the diffuser section
An imbalance between compressor axial airflow and rotational velocities
A disruption of bypass airflow through the exhaust nozzle
A slow increase in throttle movement during a headwind condition
Which of the following defines a compressor ‘blisk’?
Compressor disks and blades are matched at the manufacturer and must be replaced together during overhaul
Compressor blades and disk are manufactured as a single assembly
Compressor disks and blades are constructed from the same material
A blisk is a manufacturer-specific name for a disk
What is the purpose of a compressor blade root locking device?
Prevents the blade from moving axially
Allows the blade to stretch during operation
Forms part of the compressor blisk during assembly
To prevent blade twist when the engine is operating at high power settings
Why are swirl vanes (pre-swirl vanes) used at the inlet to the combustion chamber?
They protect the inner liner by cooling the incoming primary airflow.
They increase the incoming airflow velocity, thereby increasing overall thrust.
They reduce the velocity of the incoming airflow and help with fuel atomization.
Swirl vanes are used to provide airflow back-pressure to reduce the risk of compressor stall.
What is the purpose of the combustion section in a gas turbine engine?
Convert potential energy into kinetic energy for doing work
Maximize potential energy through the turbines, to be converted into kinetic energy at the exhaust nozzle for producing thrust
Turn the compressors, which turn the turbines to produce thrust
To ensure 100% propulsive efficiency by maintaining a 1:1 ratio of thrust versus aircraft speed
What purpose do the dilution holes serve towards the aft end of the combustion chamber?
Cool the air prior to entering the turbines
Help to centre the flame
Aid in atomizing the fuel for combustion
Reduce the weight of the combustion chamber to improve thermal efficiency
Which of the following is NOT a type of combustion chamber?
Annular
Reverse flow annular
Can-annular
Inverse annular
What type of turbine uses an impeller design like that used on a centrifugal compressor?
Radial inflow
Impulse
Cup-type
Centrifugal
Why are many current turbine and stator blades manufactured with a ceramic coating?
Offers less airflow resistance, thereby reducing back pressure
Decreases the overall weight of the blades
Improves thermal efficiency
Increases propulsive efficiency by generating higher thrust
What purpose do the turbines serve in a gas turbine engine?
Produce thrust
Turn the compressors
Increase airflow static pressure in order to maximize exhaust nozzle thrust
Reduce the temperature of the hot gases by mixing it with cold bypass air
What conditions are required to enable reverse thrust selection on most gas turbine engines?
Aircraft on ground, throttle at idle, reverse selected
Aircraft on ground, reverse selected, spoiler panels deployed
Aircraft on ground, reverse selected, throttle advanced above idle
Aircraft in flight or on ground, reverse selected, throttle advanced above idle
What is the most important procedure to accomplish prior to working on a thrust reverser?
Carry out a dry cycle (motoring) of the engine to ensure there is no residual fuel in the combustion and exhaust sections.
Carry out lockout procedures on the applicable reverser, in accordance with the maintenance manual.
Pull the ignition and thrust reverser circuit breakers and advise all personnel that you are working on the reverser system.
Ensure hydraulic and pneumatic systems are turned off and locked out.
What type of loads do ball bearings support when installed on the main engine shaft?
Centripetal and centrifugal
Axial and torsional
Axial and centrifugal
Centrifugal and torsional
How do you determine the longest CT disk blade when measuring the blade tip-to-shroud clearances during the PT6A hot section inspection?
Measure the length of each blade from root to tip.
Lock the CT disk in place and work your way around the engine, measuring the clearance at each blade tip with feeler gauges.
Using feeler gauges, measure the tip clearance of each blade at the 6:00 position.
Rotate the CT disk, while observing (and listening) for signs of chafing between the blade tips and shroud ring.
What is the purpose of using the beta ring puller when replacing a Hartzell propeller?
Provide access to the propeller mount bolts for removal
Part of the system safety/lockout procedure
Used to remove the propeller by pulling it away (unlocking it) from the engine flange after the bolts have been removed
It is used to force the propeller into the fine position so that the sling can be attached to the propeller.
How is the Hartzell propeller aligned to ensure proper installation on the engine.
The propeller must be aligned horizontally with the engine #1 cylinder at top dead centre of the compression stroke.
The zero on the propeller flange scale must be aligned with the zero on the engine flange scale.
There is no specific procedure to install the propeller on the engine.
There are 2 dowels on the engine flange that align with holes on the propeller flange.
How is the Hamilton Standard propeller that is used in the lab project adjusted?
Adjustment screws on the left and right sides of the hub assembly
Stop nuts on the index pin under the counterweight caps
Rotating the index pin turnbarrel assembly under the hub mount
It can only be adjusted during the manufacturing process.
What is the propeller angle reading indicated on the protractor in the picture?
6 degrees
6.3 degrees
6.8 degrees
7 degrees
What is the indicated propeller angle reading on the protractor in the picture?
17 degrees
17.3 degrees
18.7 degrees
20 degrees
What action is required if you have (unsuccessfully) attempted 3 consecutive starts on the Cessna Conquest?
The starter must be replaced.
The starter must be allowed to cool for 40 seconds before attempting an additional start.
The starter must be allowed to cool for 30 minutes before attempting an additional start.
The starter brushes would require replacement
Choose the correct definition of an engine cycle from the following choices:
One revolution of the engine (relating to rpm)
An engine start, run & shutdown
2 complete flight legs (home base to destination & return to home base)
A two or three-wheeled cycle operated by an engine
Which of the following describes engine condition trend monitoring?
Continuous monitoring of engine data to determine deterioration & wear over time
Carrying out daily power assurance checks to determine continued engine serviceability
Sending the engine out for annual overhauls to check for internal component wear
Ensuring that the engine is appropriately dressed for the current fashion trends
Which answer does NOT represent an advantage of engine trend monitoring?
Reduces the service life of an engine
Increases dispatch reliability and safety
Helps determine the source of problems
Allows early detection of engine deterioration
What function can be performed if there are signs of engine performance deterioration over time?
A compressor wash can be carried out.
The engine must be discarded, as it has reached the end of its service life.
Nothing is required, as this is acceptable until the engine reaches the end of its service life.
A complete overhaul must be accomplished.
Identify the NDT method that is used to inspect non-porous materials for surface defects.
LPI (liquid penetrant inspection)
MPI (magnetic particle inspection)
Ultrasound
Eddy current
What type of combustion chamber is installed on the JT8D engine?
Annular
Reverse flow annular
Can-annular
Single-can type
Identify the component shown in the picture of the JT8D.
Oil tank
Ignition exciter box
Starter
Fuel pump assembly
Which part of the JT8D engine is represented by airflow station 4?
Low pressure compressor discharge (6th stage)
High pressure compressor discharge (8th stage)
High pressure compressor discharge (13th stage)
Exhaust
Where is the JT8D accessory gearbox located?
Top of the engine
Left side of the engine
Right side of the engine
Bottom of the engine
Choose an aircraft that uses the JT8D as its powerplant from the following ...
Boeing 747
Airbus A340
Boeing 737-200
CRJ 200
What type of fuel control system is used on the JT8D engine?
Hydro-mechanical
Hydro-pneumatic
FADEC
Supervisory EEC
What type of aircraft would use a bellmouth inlet duct?
Supersonic aircraft used for certification testing and airshows to reduce noise levels
Subsonic aircraft
Supersonic aircraft
Test engines during certification testing
Choose the FALSE statement regarding the use of a modular engine design from the following:
Some modules can be replaced without removal of the engine from the aircraft.
Reduces maintenance downtime
The engine must be disassembled in a shop to access each of the modules for inspection.
Reduces maintenance costs
How are inlet airflow disturbances reduced on engines with S-duct intakes?
By installing inlet panels that open during low power settings and close during high power settings
A layer of carbon fibre composite lining is fixed to the intake.
Through the use of vortex generators
By using nozzle brushes around the fan perimeter
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