Intro/History/Ch 1-4

Question 1

First Helicopter to receive civilian certification

Answer 1

Bell 47

Question 2

List at least 5 advantages of elastomeric bearings

Answer 2

1- no lubrication necessary because the elastomer is the lubricant
2- no disassembly required because the bearing is exposed
3- no seizure is possible because of its design
4- elimination of the brinelling, pitting, and galling associated with conventional bearings
5- reduction of vibration and shock due to the use of elastomers
6- boots and seals are eliminated because no grease or oil is required
7- environmental resistance is increased because bearing is bonded forming one unit
8- controlled stiffness may be obtained
9- extended service life is quite common, with life of 5X that of an ordinary bearing
10- reduction of parts necessary for component has been made by elimination of close tolerances, seal retainers, and lubrication systems

Question 3

3 types of rotor heads

Answer 3

1- rigid
2- semi rigid
3- fully articulated

Question 4

Causes for blade tip stall

Answer 4

1- insufficient airspeed
2- too great an angle of attack
3- heavy wing loading

Question 5

How is translating tendency normally corrected

Answer 5

By offsetting the mast

Question 6

In a hover, what is used to control direction?

Answer 6

Tail rotor (anti-torque) pedals

Question 7

In forward Flight, what is used to control direction?

Answer 7

Cyclic and anti-torque pedals

Question 8

What is a stabilizer bar?

Answer 8

A dynamic component used on some Bell helicopters to ensure rotor stability

Question 9

What does CARs stand for?

Answer 9

Canadian Aviation Regulations

Question 10

Define angle of attack

Answer 10

The acute angle between the direction of relative wind and the chord line of an airfoil

Question 11

Define centre of pressure

Answer 11

The imaginary point where the resultant of all aerodynamic forces of an airfoil is concentrated

Question 12

Describe Coriolis effect

Answer 12

The change in blade velocity to compensate for the change in distance at the centre of the axis of rotation as the blade flaps

Question 13

What does the flapping hinge correct for?

Answer 13

Dissymmetry of lift

Question 14

What does the lead-lag (or drag) hinge correct for?

Answer 14

The Coriolis effect

Question 15

Name the 2 classes of gaskets/seals

Answer 15

Static and dynamic

Question 16

Name the 2 types of seals

Answer 16

Labyrinth and Face (carbon seal)

Question 17

Define Dissymmetry of lift

Answer 17

The unequal lift across a rotor disc that occurs in forward flight due to the difference in airflow over the advancing and retreating blades

(Advancing blade more lift than retreating blade, in forward flight)

Question 18

What do you do in a ground resonance?

Answer 18

Apply power and take off

Question 19

Define gyroscopic procession

Answer 19

Reaction occurs 90 degrees to impact

Swashplate corrects for this

Question 20

In flight, what forces determine main rotor head conning angle?

Answer 20

Centrifugal force, lift, weight of helicopter

Question 21

What type of rotor head is affected by ground resonance?

Answer 21

Fully articulated

Question 22

What are the 4 types of gears used in helicopters?

Answer 22

• straight tooth
• helical
• bevel
• spiral bevel

Question 23

What does CHR stand for?

Answer 23

Component Historical Record

Question 24

When do you level an aircraft?

Answer 24

• weight and balance

- Rigging

Question 25

Describe a pinch fit with regards to a bearing install

Answer 25

Prevents bearing outer race from rotating

Question 26

Describe roller staking process

Answer 26

Drill press used to swagged the sleeve

Question 27

Describe the ATA system

Answer 27

Look up definition
Something about being assigned same number for trouble shooting, maintenance, etc
Ex; all helicopters have the same transmission ch #

Question 28

List the 6 safety precautions that must be observed when ground handling

Answer 28

1- A bar must be used both for raising and lowering manually operated wheels
2- This bar must be secured firmly to the ground handling wheel unit
3- The personnel must stand clear of the bar, in case of slippage, when the helicopter is raised and lowered
4- Hands or feet must never be placed under the skid gear during the raising or lowering operation
5- All locking devices and pins must be firmly in place prior to releasing pressure from the bar
6- UNDER NO CIRCUMSTANCES should the Helicopter be started with the ground handling wheels in the down position

Question 29

What is the term used for a set of 3 matched bearings? Set of 2?

Answer 29

Triplex and Duplex

Matched sets are marked with a large V scribed across outside surface of bearing to ensure proper installation

Question 30

In 1907, ____ received the distinction for first free flight.

Answer 30

Paul Cornu. He rose to 5ft with a passenger hanging underneath

A few weeks earlier, Louis Breguet and Professor Richet did not receive the title of First flight because it had to be steadied by 4 assistants

Question 31

Who drew the first recorded drawings of a helicopter machine

Answer 31

Leonardo da Vinci in 1483

Question 32

Described autorotation. What must be disengaged in order to autorotate?

Answer 32

• Process of producing lift with the rotor blades as they freely rotate from a flow of air up through the rotor system
• rotor system will disengage, leaving the rotor system to move freely in its original direction and produce lift, allowing the helicopter to glide

Question 33

Who created the flapping hinge and lead-lag (or drag) hinge?

Answer 33

Juan de la Cierva

Question 34

Hanna Reitsch

Answer 34

Was the first female helicopter pilot that demonstrated the FW-61 in 1937, which later broke all existing records and helped to remove any doubts regarding the future of the helicopter.

Question 35

What where the 3 main problems faced with early Helicopter designs?

Answer 35

• power to weight ratio
• gyroscopic procession
• dissymmetry of lift