Book 2 - Fan Blades and Rotor Disc

Question 1

the high bypass fan can produce __% of engine thrust

Answer 1

the high bypass fan can produce 75% of engine thrust

Question 2

it is a requirement that if a blade becomes _________ it must not __________ then engine casing and hazard the aircraft, so a ____________ ring is necessary around the fan and the heavier the blade, the heavier and stronger the ring needed

Answer 2

it is a requirement that if a blade becomes DETACHED it must not PENETRATE then engine casing and hazard the aircraft, so a CONTAINMENT ring is necessary around the fan and the heavier the blade, the heavier and stronger the ring needed

Question 3

there is an aerodynamic feature of a the containment ring, in that it is designed to ____ the blade, so the it will be swept down the fan duct before the next _____ can hit it

Answer 3

there is an aerodynamic feature of a the containment ring, in that it is designed to FLIP the blade, so the it will be swept down the fan duct before the next BLADE can hit it

Question 4

mid-span shrouds or _________ prevent blade flutter or flapping due to aerodynamic instability. the snubbers, also known as _________, form a virtually solid ring around the fan when rotating to act as a stiffener, but they impose a penalty by causing a ________ loss and reduced ____ area, which reduces __________

Answer 4

mid-span shrouds or SNUBBERS prevent blade flutter or flapping due to aerodynamic instability. the snubbers, also known as CLAPPERS, form a virtually solid ring around the fan when rotating to act as a stiffener, but they impose a penalty by causing a PRESSURE loss and reduced FLOW area, which reduces EFFICIENCY

Question 5

Rolls Royce have introduced a wide _____ fan blade (WCFB), the advantages of which are:

• _______
• _______, therefore impose less load on root per given RPM
• move more ___ per given RPM
• better able to centrifuge ___ into the fan duct, protecting core engine
• more _____, thus do not require snubbers. cleaner airflow, less losses, more __________

Answer 5

Rolls Royce have introduced a wide CHORD fan blade (WCFB), the advantages of which are:

• LIGHTER
• SHORTER, therefore impose less load on root per given RPM
• move more AIR per given RPM
• better able to centrifuge FOD into the fan duct, protecting core engine
• more RIGID, thus do not require snubbers. cleaner airflow, less losses, more EFFICIENT

Question 6

the _____ disc takes the load of all the blades and therefore needs to be extremely ______

Answer 6

the ROTOR disc takes the load of all the blades and therefore needs to be extremely STRONG

Question 7

in some cases, blades are pushed into a a ____ and then slid around the ____________ of the disc until disc is full. final move is to insert a ____ to prevent the first blade from falling out

often, the fan blades are slid in from the front with ________ (annulus fillers) in between each blade to maintain the correct distance apart

Answer 7

in some cases, fan blades are pushed into a a SLOT and then slid around the CIRCUMFERENCE of the disc until disc is full. final move is to insert a STOP to prevent the first blade from falling out

often, the fan blades are slid in from the front with PLATFORMS (annulus fillers) in between each blade to maintain the correct distance apart

Question 8

the fan blade roots are usually lubricated with an ________ lubricant before installation

Answer 8

the fan blade roots are usually lubricated with an APPROVED lubricant before installation

Question 9

fan blades with snubbers may develop a problem known as ________ (overlapping of snubbers). should this happen, the blades can be un________ and allowed to continue in service for a specified (usually _____) time

Answer 9

fan blades with snubbers may develop a problem known as SHINGLING (overlapping of snubbers). should this happen, the blades can be unSHINGLED and allowed to continue in service for a specified (usually _____) time