Heli Final

Question 1

what are the four blade movements

Answer 1

feathering
teetering
flapping
lead/lag

Question 2

what are the three basic types of rotor heads

Answer 2

rigid
semi-rigid
fully articulated

Question 3

what is the main rotor strap? what purpose does it serve

Answer 3

they are wraps fine steel wire between two bearings.

they are designed to retain the rotor blades while still allowing for movement of the blade

Question 4

what is a droop stop? what type of rotor heads will they be found on

Answer 4

droop stops limit how far down a blade will settle, eliminating any damage to the airframe.

will be found on rotor heads that flap

Question 5

what are teeter stops? what are the two types

Answer 5

stops that limit the downward travel of semi rigid rotor heads

static and dynamic stops

Question 6

what are the different ways a main rotor head can be lubricated

Answer 6

oil or grease

self lubricated components

life lubricated components

Question 7

what is an example of a self lubricated component

Answer 7

Teflon Bearing

Question 8

what does the term life lubricated mean

Answer 8

the component is lubricated by the manufacturer and will not be re-lubricated for the usable life of the component

Question 9

what is a rotor disc

Answer 9

the total surface area occupied by the main rotor assembly while in motion

Question 10

what is coning

Answer 10

the upwards angle of the rotor blades while in flight. resultant of the creation of lift

Question 11

what is an autogyro? how does it differ from a helicopter

Answer 11

an autogyro uses an un controlled / unpowered rotor system to produce lift. can only produce lift during forward flight

Question 12

what effect does centrifugal force have on rotor blades in motion

Answer 12

it will cause the rotor blades to stay flat until lift is increased

Question 13

what is Nr

Answer 13

rotor RPM

Question 14

when lift is increased, what happens to the rpm of the main rotor

Answer 14

the RPM always stays constant at 100%. all flight inputs are done by changing blade pitch, not blade speed

Question 15

what defines a hover

Answer 15

all forces are equal

zero movement relative to wind speed

Question 16

what is gyroscopic precession

Answer 16

any blade pitch adjustment made during directional flight must occur 90 degrees early

Question 17

how will the airframe react to the torque forces of the main rtor

Answer 17

the airframe will always react in the opposite direction of the main rotor

Question 18

what is induced flow

Answer 18

the direction of airflow through the rotor blades during directional travel

Question 19

what is translational lift

Answer 19

the transition from hover to directional flight. reduces the induced flow angle and causes light airframe buffeting

Question 20

why is there no ground effect when flying frward at low altitude

Answer 20

the rotor downwash is propelled to the rear of the aircraft and does not create an air cushion for the aircraft to rest on

Question 21

what is dissymmetry of lift

Answer 21

difference in blade speeds while in directional flight

Question 22

what are the solutions for dissymmetry of lift

Answer 22

flapping hinge

differential cyclic

Question 23

what is differential cyclic

Answer 23

a difference in blade pitch dependent of position

Question 24

what is the law of conservation of angular momentum

Answer 24

when the centre of mass of a rotating object moves towards the centre of rotation, the object will accelerate

Question 25

what are the solutions for the law of conservation of angular momentum problem

Answer 25

lead lag hinge

underslung mounting

Question 26

what is mast bumping

Answer 26

the rotor head striking the mast. only occurs in underslung rotor heads

Question 27

what pilot input controls yaw? how is yaw controlled

Answer 27

anti torque pedals at the pilots feet

controlled by changing the pitch angle of the tail rotor blades

Question 28

what control devices are incorporated into the tail rotor system

Answer 28

push pull tubes or teleflex cables connected to bell cranks which move walking beams to change pitch

Question 29

what are some examples of additional controls located on the collective

Answer 29

landing lights
start switch
governor controls
idle release
throttle twist grip 
pop out float trigger

Question 30

what are some additional controls that are located on the cyclic

Answer 30

push to talk radio
cargo hook release
trim

Question 31

what is the purpose of the mixing unit

Answer 31

converts individual cyclic and collective input into a common set of outputs

prevents collective inputs from altering cyclic position

Question 32

what is centrifugal twisting force? what is used to combat it

Answer 32

a force acting on a rotor blade attempting to return it to a low pitch angle

counterweights and collective spring

Question 33

what is aerodynamic twisting force

Answer 33

forces acting on rotor blades to return them to a higher pitch

Question 34

what are hydraulic servos used for

Answer 34

provides flight control boost and eliminates rotor system feedback

Question 35

what are the different types of gearboxes

Answer 35

main rotor
tail rotor
intermediate
combining

Question 36

how is the main rotor gearbox mounted on a bell 206

Answer 36

using 2 a-frame support links to hold the gearbox and still allow movement

Question 37

when is a clutch required on a helicopter

Answer 37

for all piston engine aircrafts and all direct drive turbine engine aircrafts

Question 38

what are the two types of turbine engine

Answer 38

free turbine and direct drive turbine

Question 39

what type of helicopters have freewheeling untis? are any of them manual

Answer 39

all helicopters have freewheel units and they are all automatic

Question 40

what two measurements are displayed on a dual tach

Answer 40

engine RPM and rotor RPM measured in percent

Question 41

what are drive shaft couplings

Answer 41

they are flexible metal plates or greased bearings that allow the drivetrain to move with the airframe without being damaged

Question 42

what is a side effect of tail rotor anti-torque forces

Answer 42

translating tendency (lateral drift)

Question 43

how do you counteract translating tendency

Answer 43

Pilot

mixing unit which applies slight lateral cyclic when collective is moved

Question 44

why mount the tail rotor higher on the vertical stab

Answer 44

more ground clearance

brings the tail rotor in line with CofG

Question 45

what is a delta hinge

Answer 45

the teeter hinge on a tail rotor that is not at a right angle with the blades. causes blades angle of attack to lower when flapping up

Question 46

what do strakes do

Answer 46

the eliminate the ow pressure zone on one side of the tailboom which increases tail rotor efficiency

Question 47

what is autorotation

Answer 47

the state of flight where the main rotor system is being turned by the action of relative wind instead of engine power

Question 48

what are the different regions of the rotor disc duriong autorotation

Answer 48

stall region
from centre to 25% of the blade

autorotation region
25 - 75% of blade

driven region
75% - blade tip

Question 49

what are the different multi rotor configurations

Answer 49

co-axial (stacked)

Tandem (one in front of the other)

Synchrocopter (intermeshing)

Question 50

what is a design feature that helps to overcome nose down tendency

Answer 50

forward tilt of mast or horizontal stabilizers

Question 51

what is the purpose of a synchronized elevator

Answer 51

changes the CofG

Question 52

during start up, fully articulated rotor blades will have a tendency to what?

Answer 52

lag

Question 53

how are coning stresses reduced in rotor blades

Answer 53

pre coning angles

Question 54

what must be recorded during autorotational rigging

Answer 54

a/c weight
pressure altitude
temperature
rotor rpm