Exam 1

Question 0

Needs necessary for engines for modern military applications such as multi role aircraft

Answer 0

Drag of the engine
High specific thrust
Short takeoff and vertical landing

Question 1

What are the advantages of turbine engines over rockets, ramjets, and pulse jets?

Answer 1

• can operate without forward momentum

* do not need to carry an oxidizer

Question 2

How can missile firing and operating the aircraft at high angles of attack effect the engine

Answer 2

Can stall the compressor blades

Surge

Question 3

What percent of the fuel burned in the combustion section of a turbine engine is used to drive the compressor?

Answer 3

66%

Question 4

Disadvantage of interstage bleeds vs the advantage of variable stators during turbine engine part speed operation

Answer 4

When using the bleeds energy is wasted through the work done to compressor air, air that is not used for combustion

Question 5

Advantages of using a multiple chamber combustor system

Answer 5

• reduces time to maintain combustor
• can accommodate larger combustors for better emissions
• testing during development is simpler using only one chamber

Question 6

Regarding military engines and being able to cope with missile plume ingestion, what are some conditions that might cause extinction of hue flame in the combustor?

Answer 6

• momentary increase in inlet mass flow and temp

* secondary effect of depletion of oxygen

Question 7

What is the main purpose of the rotating turbine blades?

Answer 7

Drive the compressor
Accessory gearbox
Power the prop/rotor blades/fan

Question 8

What are the consequences with new technology that allows for turbine blades to withstand more heat

Answer 8

High temps in turbines
Less cooling air
Smaller compressor
High % of fuel used for thrust
Lower TSFC

Question 9

What is the purpose of using bleed air on the turbine case?

Answer 9

Cooling turbine blades

Question 10

What tool is used in access ports in turbine engine casings that support health monitoring

Answer 10

Borescopes

Question 11

What engine indicating probes are typically found in exhaust ducts

Answer 11

Thermocouples (EGT)

Pressure ratio probes (EPR)

Question 12

Why are thrust reverses not typically used below 50 knots

Answer 12

Foreign object damage

Question 13

What are the circumstances for which a pilot could accidentally over temp an engine during reverse thrust

Answer 13

On a non computer controlled engine

Question 14

How does burning fuel in the afterburner increase thrust

Answer 14

Increase thrust by adding fuel to the exhaust gasses and igniting it

Question 15

What greatly affects operational noise levels of an aircraft

Answer 15

Engine design and airframe

Question 16

Emissions produced from a gas turbine engine are a direct result of what

Answer 16

The combustion process

Question 17

Why is the starter typically the basis design with regards to the accessory drive system

Answer 17

Starter often provides the highest torque that the drive system encounters

Question 18

What type of forces can ball bearings withstand

Answer 18

Radial and axial forces

Question 19

How does a labyrinth seal work?

Answer 19

Seal creates a resistance to airflow by forcing the air to transverse through a series of fins

Question 20

What is the correlation between the FMU and VIGVs

Answer 20

The FMU is a servo pressure source for a remote actuator to operate the VIGVs of the HP compressor

Question 21

How does fuel within the wing tanks rarely go below -35 degrees Celsius

Answer 21

Heating of he wing structure caused by the aircraft speed

Question 22

What is the function of a FOHE

Answer 22

Extract heat from the engine oil providing oil cooling and fuel heating

Question 23

Why is it that turboprops have spa separate oil reservoir that cannot be depleted by leakage from the basic oil system

Answer 23

So that the propellor pitch can be feathered if the engine has to be shut down inflight after loss of oil

Question 24

What is he correlation between FADEC and EEC

Answer 24

At the center of the FADEC is he EEC

Question 25

What does the FMU do with unwanted fuel and what are the consequences

Answer 25

Cycles it back through causing he fuel to heat up