Mid Term but its the final instead Flashcards
what are the components of a main rotor blade
leading edge trailing edge span chord tip root
what are the types of rotor blades
wooden
metal
composite
what is the difference between BIS and BIM
Blade inspection method - sikorsky
Blade inspection system - bell
what are the different loads that can be applied to a bearling
radial and axial
what are the different fit tolerances for bearings
loose fit - > 1”
Press fit - = 1.0”
Interference fit - < 1”
what are the different types of oil seals
Lip seal
Carbon Magnetic
Labyrinth
Hydrodynamic
will a labyrinth seal work statically or dynamically
only works dynamically (with oil or liquid present
which seals will work statically
all seals except labyrinth seals work both statically and dynamically
what is a major drawback of a lip seal
can cut a groove in the shaft over time
what is brinelling? how can you identify false brinelling
brinelling is when a bearing begins to form dents caused by excessive load. false brinelling is caused by vibration, usually in transport.
what are the functions of a gearbox
transmit power
change direction
increase / decrease speed
what are the types of gearbox
main rotor gearbox - speed decreasing
tail rotor gearbox - usually speed decreasing
intermediate gearbox - no change in speed, only direction
combination gearbox - multi engine helicopters
what is the accessory drive used for
running components from the main system such as:
tach gen
hydraulic pump
oil pump
what are the different types of gears within a gearbox
straight tooth helical bevel spiral bevel worm planetary
what is the difference between a bevel and spiral bevel gear
bevel gear tapers in and has straight teeth. a spiral bevel gear tapers in but the teeth are slanted
what are the components of a planetary gear assembly
sun gear - input
ring gear
planets
spider - output to planets
what is the formula to calculate planetary gear ratio
of sun teeth + #of ring teeth / #of sun teeth
what is the difference between lash and pattern
lash is how well the teeth mesh with each other.
pattern is where the gears contact while moving
what control must be rigged first on a bell 206
collective
what is the max amount of exposed thread allowable on control rods
1 inch
the droop compensator is connected to what
collective stick
what precaution must be taken when raising the main rotor hub
do not let split cones fall
prior to removing main rotor blades, the nut on the ___ edge must be loosened
trailing
what is the purpose of a helicopters hydraulic system
control boost
eliminate rotor system feedback
what conditions must be met when rigging flight controls
controls must:
move in the correct direction
move the correct distance
cannot touch anything they arent supposed to
two types of engine controls
Proactive - anticipate power changes and adjust. droop compensator / anticipator
Reactive - sensing workload and adjusting to maintain RPM. governor
all helicopters have oth
main rotor grips must be secured from what
rotating beyond 90 degrees
what are the different kinds of bearings
ball
roller
spherical
elastomeric
what are the configurations of ball bearing
single row deep groove
single row angular
four point contact
duplex angular contact
what are the different configurations of roller bearing
single row cylindrical
needle roller
single row tapered
what does life lubricated mean
bearing is coated in teflon or other low friction surface
when rigging flight controls, what must be rigged first
collective
where is the droop compensator
connected to the collective stick
swashplate friction is between bearing set and what
pivot sleeve
when installing a beveled washer, where does the bevel go
against the bolt head
what are the three vibration ranges
Low - less than 500Hz - Main rotor
Medium - 500 - 2000Hz - main rotor or airframe
High - above 2000Hz - tail rotor, driveshafts, engine
types of vibrations
Lateral - out of balance condition. center of mass out of line from center of rotation. adjusted by balancing blades statically or dynamically
Vertical - out of track condition. blades are not producing equal amounts of lift. adjusted by changing pitch links or blade tabs
track adjustments
speed sensitive - vibration changes with forward airspeed. tab adjustment. up will cause blade to fly higher but cause more aerodynamic drag
non speed sensitive - consistent vibration. pitch link adjustment (shorter if possible)
methods of stability control
stabilizer bars and dampers. bars control blades, swashplate controls bars.
stabilizer bars are gyroscopic to dampen sudden changes
what is HUMS
health and usage monitoring system. cameras installed to monitor blade track and vibrations and provide trend monitoring data
transmitted damage
damage as a result of something happening to a different part of the aircraft.
ex - main rotor strike, T/R drive shaft found bent
when setting autorotation rpm, what adjustment would cause faster rpm
shortening pitch links
what is the purpose of hydraulic accumulators
provide limited number of control movements in the event of hydraulic failure
what is the purpose of the throttle? where does it fit in the engine control system
primarily used for start up / shut down. connected to the fuel control unit
