turbine engines

Question 1

explain the main difference and advantage of a turbofan over a turbojet engine

Answer 1

a turbofan engine uses a fan to bypass some air around the engine core and to provide thrust. the advantage is that this provides additional thrust without increasing fuel flow

Question 2

name the major components of a gas turbine engine

Answer 2

air inlet
compressor section
combustion section
turbine section
exhaust section
gearbox
accessory section

Question 3

what determines the amount of airflow through a turbine engine?

Answer 3

the forward speed of the aircraft, compressor speed, and air density

Question 4

name the two types of compressors commonly used in turbine engines

Answer 4

axial and centrifugal flow

Question 5

name two different methods for attaching turbine engine rotor blades to the rotor disks

Answer 5

dovetail
root
bulb
fir-tree

Question 6

what are the different types of combustion chambers used in turbine engines

Answer 6

can
annular
can-annular
reverse flow annular

Question 7

what is a split compressor system

Answer 7

also called dual or twin spool compressors. these are connected to the turbine section with two rotor shafts, one inside the other

Question 8

what prevents the combustion chambers from burning

Answer 8

cooling air along the inside of the liner

Question 9

what is the purpose of the interconnecting tubes attached between the can-type combustion chambers

Answer 9

for flame propagation during engine start

Question 10

what functions do axial flow turbine nozzles perfom

Answer 10

they direct the mass airflow to drive the turbine rotor at a specific angle

Question 11

how is thermal stress relieved on a turbine disc

Answer 11

by directing bleed air onto the face of the disk, or by grooves being cut in the disk

Question 12

what are carbon seals used for in turbine engines

Answer 12

they are used as oil seals for the rotor shaft bearings

Question 13

what is shaft horsepower

Answer 13

it is an indication of the torque developed by a turboprop or turboshaft engine

Question 14

when a turbofan or turbojet engine is shut down what should the mechanic listed for during coast-down

Answer 14

any rubbing sound or other unusual noises from the engine

Question 15

what are the desired effects of turbine engine of turbine engine compressor field cleaning

Answer 15

removal of contaminant deposits from interior engine surfaces and improved engine performance

Question 16

what methods are commonly used to accomplish turbine engine compressor field cleaning

Answer 16

fluid wash and abrasive grit blast

Question 17

what type of compressor blade damage may be found when inspecting compressor blades

Answer 17

dents
galling
pitting
cracks
scratches
burrs
burns
gouges

Question 18

what is used to mark both hot and cold section parts for repair

Answer 18

layout dye, commercial felt tip marker, or chalk

Question 19

what is the effect of relative humidity on a turbojet or turbofan power

Answer 19

negligible, no effect

Question 20

what may be the indications if a turbojet or turbofan engine is out of trim

Answer 20

the engine has high exhaust gas temperature at the target engine pressure ration for takeoff power

Question 21

what would the possible cause be for a turbojet or turbofan engine having high exhaust gas temperature, low RPM, and high fuel flow at all engine pressure ratio settings

Answer 21

possible turbine damage or loss of turbine efficiency