Turbines 3 Midterm 2
What is the purpose of conducting a S.O.A.P. Test on a turbine engine?
To inspect for water contamination of hydraulic fluid
It's part of condition monitoring to ensure that the compressor and turbine blades are not eroding
Check for metallic particle content in the engine oil
Determine that the compressors are clean (to optimize engine performance)
Which of the following is NOT a type of fuel control system?
Hydro-mechanical
Hydro-pneumatic
FADEC
Supervisory hydro-photonic
How is combustion sustained after an engine start is completed on most turbine engines?
Both igniters are selected on.
A single igniter remains energized.
Combustion is self-sustained, with both igniters selected to 'Off' or 'Auto.'
A single igniter pulses once every minute.
Which type of engine commonly uses a glow plug as its ignition source?
High bypass turbofan
Medium bypass turbofan
Small gas turbine engine
All auxiliary power units (APUs)
You have confirmed that the ignition system has been turned off in the flight deck. What additional safety procedures (if any) are required prior to disconnecting an ignition lead on a high energy ignition system?
Pull the applicable circuit breaker(s) in accordance with the maintenance manual.
Carry out an engine dry cycle (i.e. Motor the engine using the starter, without turning on fuel or ignition)
Pull the applicable circuit breaker(s) and wait the allotted time in accordance with the maintenance manual.
No additional procedure is required, as long as the system has been selected off in the flight deck.
When would ignition cut out during an engine start?
Ignition shuts off when the starter cuts out.
At or near completion of engine start
Ignition stays on at all times to sustain combustion.
Only when it is manually selected off in the flight deck
What ATA chapter is engine ignition?
73
74
76
80
What are you primarily checking when inspecting the tip of an igniter plug?
Signs of erosion
Carbon buildup
Unburned fuel deposits
Foreign object damage (FOD)
What procedure must be accomplished prior to carrying out an engine ignition test (firing the igniters)?
Motor (dry cycle) the engine to clear out any residual fuel in the combustion chamber.
Pull the ignition circuit breakers.
Place the aircraft on jacks to disable the fuel pumps.
Disconnect the igniter leads from the exciter box(es).
What air source provide engine nacelle cooling and ventilation?
Low pressure (LP) turbine discharge air
High pressure (HP) turbine discharge air
Cabin air
Ambient or fan discharge air
How are the various nacelle cooling and ventilation areas identified on most engines?
Area
Zone
Station
Reference
What is the purpose of pressurizing engine bearing compartments with compressor discharge air?
Helps to keep the bearings clean
Atomizes the oil entering the bearing compartment
Prevents oil from leaking past the bearing compartment seals
Provides bearing compartment cooling
Which engine system does NOT use compressor discharge air for its operation?
Active clearance control
Engine anti-ice
Generator cooling
Engine x-bleed (pneumatic) starting
What is another common name for an engine bearing compartment?
Housing
Sump
Assembly
Vestibule
Select a possible air source for an engine active clearance control system from the following:
Ambient (external) air, regulated by a heat exchanger in the pylon
Compressor and fan bleed air
Turbine bleed air
Conditioned cabin air, regulated through a dedicated heat exchanger
What ATA chapter is engine air?
73
75
80
36
What percentage of engine core airflow is used for combustion chamber cooling on newer engines?
35%
55%
75%
80%
What purpose is served by all the small holes found on engine turbine blades?
They reduce the weight of the blades.
They provide a means of cooling the blades.
They provide a means of allowing blade expansion to minimize tip clearance.
The holes are designed to reduce airflow disturbances around the blades.
What is the primary reason that ventilation air is provided in engine compartments?
Helps the engine breathe better
It's part of the active clearance control system used to reduce tip clearance between the compressor blades and engine casing.
Reduces the risk of compressor stall
Removes vapours that could potentially ignite
Which engine parameter will commonly use a tach generator to provide display information?
Engine torque
Engine pressure ratio (EPR)
N2 speed
E.G.T.
Which of the following is an engine ‘performance’ indicator for determining takeoff thrust on a double-spool turbofan engine
E.G.T.
Torque
N2 (core) speed
N1 (LP) speed
Which engine indication would be displayed by a torque oil pressure system?
Engine oil system pressure
Engine pressure ratio (EPR)
Power indication for a turboprop
Manifold pressure for a turbojet
Which engine parameter is referenced to determine when to select fuel & ignition 'on' during a double-spool engine start?
Oil pressure
N1 speed
N2 speed
Engine pressure ratio (EPR)
Identify an example of an engine 'condition' indicator from the following:
Engine pressure ratio (EPR)
Exhaust gas temperature (EGT)
Fan speed (turbofans)
Torque percentage (turboprops)
Which of the following is a 'performance' indicator on a turbofan engine?
Torque oil pressure
Torque percentage
Fan speed (N1)
Exhaust gas temperature (EGT)
Which two parameters are used to determine engine pressure ratio (EPR)?
High pressure (HP) compressor discharge pressure and total inlet pressure
Total exhaust gas pressure and total inlet pressure
Total exhaust temperature and low pressure (LP) compressor discharge pressure
Total exhaust gas pressure and total inlet temperature
Where is the cold junction of an EGT indication system located?
At the thermocouples in the engine exhaust
In the indicator (gauge)
At the engine connector
In the resistance spool
Which two metals commonly make up an exhaust gas temperature (EGT) thermocouple?
Chrome and aluminum
Chromel and alumel
Zinc and nickel
Silver and chromium
What unit of measure is most commonly displayed on fuel flow indicators?
Pounds per hour
Kilograms per minute
Cubic meters per hour
Cubic meters per minute
What is the principle of operation for an engine vibration transducer?
Piezo-electric effect (vibrating crystals)
Electro-magnetic induction
Electro-transformative
Mutual induction
Choose which of the following is NOT a common oil system parameter indicated in the flight deck?
Oil pressure
Oil temperature
Oil quantity
Oil flow
What does the engine pressure ratio (EPR) represent?
Positive engine rotation during start
A measure of engine thrust
A measure of rotor rpm
A representation of high exhaust gas temperature (EGT)
Under what ATA Chapter in the MM or IPC will the oil system be found?
29
77
78
79
What is the function of a turbine engine oil system?
Carry debris to the oil filter
Lubricate gears and bearings
Remove heat from the engine
All of the above
Select the that best describes the most commonly used synthetic turbine oils.
Type 1 OIL MIL-PRF-7808
Type 2 OIL MIL-PRF-23699 (HTS)
Type 3 OIL (No MIL spec)
Type 2 and Type 3 are commonly used today
What is the purpose of the oil scupper?
Is used to filter the oil.
Is used to drain away oil while servicing to prevent a possible fire hazard.
It has a magnet to inspect the oil for ferrous metal contaminants.
It turns on a warning light in the Flight Deck to warn the pilot of oil contamination.
Select the fluid that has the lowest viscosity
Water
Turbine Oil Type 2
Ketchup
Hydraulic fluid type 5606 (red fluid)
Select the that best describes a Dry Sump oil system.
Is never used on large airliner engines
Dry sump system does not require an oil filter
All the oil is stored inside the engine
Has an external oil tank for oil storage
Select the that best describes an Oil Filter bypass condition.
The pressure drop across the filter is causing the bypass valve to open
There will be a Green pop-out indicator at the filter
The Oil system quantity is low, you must add oil to top-up the quantity
The oil filter is in perfect and normal condition
The Fuel/Oil Heat Exchanger has 3 modes of operation, which mode would apply to an engine that is running and all systems operating up to temperatures?
�P By-Pass Mode
Hot Mode
Cold Mode
Intermediate Mode
Where would you typically find a magnetic chip detector?
In the flight deck to provide quick and easy analysis for the pilots
In the oil pressure circuit
In the oil scavenge circuit
Attached to the oil dipstick
Which of the following is NOT a function of engine oil?
Lubrication of moving parts
Remove heat from the parts
Cushions metal to metal contact
Cools the fuel prior to entering the combustion chamber
What is the purpose of the engine oil tank 'scupper.'
Catches spilled oil during servicing and drains it away from the engine
Cleans the oil during servicing
Removes ferrous materials from the oil return
Removes ferrous materials from the oil supply
What does 'low viscosity' mean when discussing engine oil?
The oil is very thin
The oil is very thick
The oil is not compatible with the engine
The oil has a lower specific gravity than water
When is oil normally serviced on a typical turbine engine?
While the engine is operating (running)
Immediately after engine shutdown
5 to 30 minutes after engine shutdown
Greater than 2 hours after engine shutdown
What type of oil system uses scavenge pumps to return oil to an externally mounted tank?
Wet sump
Dry sump
Hot tank
Cold tank
Which pump is NOT used as an oil system pump?
Vane
Gerotor
Gear-type
Piston
What is the purpose of the lockout installed on an oil filter differential 'pop-up' indicator?
Prevents a false filter clogged indication when the oil is cold
Prevents a false filter clogged indication when the oil is hot
Used by maintenance to lock out the oil supply when replacing the filter
Prevents contaminants from leaving the filter and entering the oil system
What is the primary purpose of conducting a 'S.O.A.P.' test on engine oil?
Checks the chemical stability of oil received from the manufacturer
Removes suspended particles from the oil in the system that the filter can't capture
Used to determine the oil viscosity at various temperatures
A process used to inspect the oil for metal particles
Which NDT process is commonly used to inspect internal engine components without disassembly?
Orthoscopic inspection
Borescope inspection
Ultrasound
Eddy current
Where are magnetic chip detectors located in an engine oil system?
In the pressure lines
In the bearing compartments
In the oil tank
In the scavenge lines
Where is excess fuel not required by the FCU routed?
There is never any excess fuel as all of it is required for combustion
Back to the inlet of the HP fuel pump
To a dedicated overflow reservoir for use during the next engine start
To the fuel tank
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