Mechanical Systems 1

Question 1

Define stress

Answer 1

Force applied to cross sectional area of an object.

Stress is the applied force or system of forces that tends to deform a body

Question 2

Define strain

Answer 2

Strain is the response system to an applied stress when material is loaded with a force that produces a stress which then causes a material to deform

Question 3

Explain tortion shear bending and hoop stress

Answer 3

Torsion: twisting force

Shear: try to slide a body apart

Bending: 1 side is squeezed and other is pulled apart

Hoop: pressure difference

Question 4

What are the basic construction members

Answer 4

Ties: purely subject to tension

Struts: members and compression

Beams: carrying loads at an angle takes loads and bending

Webs: members carrying loads in shear. ribs and the skin itself are webs

Question 5

What is stressed skin

Answer 5

Covers frame with a skin panel which can take tension and compression loads. the skin takes the loads of the diagonals

Question 6

Highlight the characteristics of a monocoque construction

Answer 6

Relies entirely on skin strength to carry loads, no internal bracing except frames, formers and bulkheads

Question 7

Briefly explain geoditic construction

Answer 7

Structural members are formed within the areodynamic shape itself

Question 8

What 2 types of trusses are used in aircraft construction

Answer 8

Warren and Pratt

Question 9

What is the disadvantage of thin metal monocoque design construction

Answer 9

Can fail when subject to relatively minor dense or creases

Question 10

Name the 3 secondary purposes of wings

Answer 10

Fuel storage
under carriage attachments
provides means of attaching the flight controls

Question 11

Highlight the principle of a cantilevered wing

Answer 11

Rib and spar arrangement with external bracing wires and struts

Question 12

Briefly outline sweepback theory

Answer 12

Only the component of the airflow perpendicular to the leading edge of the wing that affects pressure distribution and formation of shock waves

Question 13

What are stringers

Answer 13

Rigidly attached to skin all of these structures, stiffening the skin and assisting it to carry loads in the direction of their length

Question 14

Where would doublers be used

Answer 14

Around doors and windows

Question 15

What are drag wires

Answer 15

The wires that extend from front spar to rear spa and that are running diagonally from inbound to outbound

Question 16

What are the 3 Fundamental wing construction designs

Answer 16

Mono or single spar, Multi spar, Box beam/torsion box

Question 17

What is the function of a spar in wing construction

Answer 17

Carrys static weight of wings on ground

Ultimately takes loads carried by wings during flight

Question 18

What is the main use of stringers in fuselage construction

Answer 18

Give shape for the attachment of the skin

prevents tension and compression from bending the fuselage

Question 19

How do radome lighting diverters strips prevent damage

Answer 19

Decrease lighting image and transmitting it to the airframe

Question 20

During flight what loads will be felt on a cantilever wing’s spar caps

Answer 20

Compressive loads on top, tensile loads on bottom

Question 21

Name the 4 main methods of joining structure together

Answer 21

Nuts and bolts
Riveting
Welding
bonding

Question 22

Name the main components of the helicopter transmission system

Answer 22

Main rotor transmission
Tail rotor
Drive system
Clutch
Free wheeling unit

Question 23

What are the main structural members in the helicopter fuselage

Answer 23

To longitudinal Beams that form primary structure

Question 24

What forces are helicopter rotor blades subject to

Answer 24

bending and shear

Large centrifugal loads from blades during rotation

Question 25

What is an aleron station

Answer 25

Is major outboard from, And parallel 2, Is the inboard age of the aileron, Perpendicular to the rear beam of the wing

Question 26

What are nacelles stations

Answer 26

Measured either forward or behind the front spar of wing and perpendicular to a designated water line

Question 27

Name Some properties of composite materials

Answer 27

light weight High strength Can be molded into complex shapes Corrosion resistant

Question 28

Define hardness

Answer 28

Ability to resist cutting, pentration or abrasion

Question 29

What happens when a metal is cold worked

Answer 29

Increases in hardness and strength

Question 30

What 2 types of hate treatment are used on aluminum alloys

Answer 30

Solution heat treatment Precipitation heat treatment

Question 31

What percentage of carbon is in low, Medium, And hard carbon steel

Answer 31

Low 0.1 to 0.3% Medium 0.3 to 0.5% Hard 0.5 to 1.05%

Question 32

What is stainless steel

Answer 32

Steel with large amounts of caramelium and nickel

Question 33

How is steel annealed

Answer 33

Heated to just above its critical temperature, Soaked for a specific time, And then cooled

Question 34

What are the 2 methods of case hardening steel

Answer 34

Carburizing and nitriding

Question 35

Where would you use inconel metal

Answer 35

Gas turbine engines due to maintaining strength at extremely high temperatures

Question 36

What is The Matrix of composites

Answer 36

The glue that holds it together

Question 37

What is the safe life of a structure

Answer 37

Min number of flight hours or flight cycles that statistically should elapse before major failure occurs

Question 38

When could a structure be closed as damage tolerant

Answer 38

If it can continue carrying the load once a defect has occurred without affecting the integrity of the aircraft structure or safety until scheduled inspection and a repair can be carried out

Question 39

What are the 4 evolutions of flight controls

Answer 39

Simple mechanical Hydraulic, Power assisted hydraulic, Fully powered Fly by wire

Question 40

How a cable fitting attached 2 cables

Answer 40

Swag using metal collars pressed onto the cable

Question 41

Explain the construction of 7x19 extra flexible wire

Answer 41

7 strands, 19 separate wires in each strand

Question 42

What is a lock clad cable

Answer 42

An aluminium tube swagged over parts of the cable. Causes steel cable to expand a similar expansion rate to aluminum structures

Question 43

How are cables fitted through pressure bulkheads

Answer 43

Go through a special pressure retaining fairlead to reduce the air leakage around cable

Question 44

Why would you use a bell crank

Answer 44

To change directions and a push pull rod system Gain or decrease mechanical advantage

Question 45

What is a torque tube

Answer 45

Tube which transmits rotary motion

Question 46

Why have secondary stops

Answer 46

They are used as override stops to prevent stretching of cables and damage to the control system during violent maneuvers

Question 47

Briefly describe the basic rigging procedure of an aircraft

Answer 47

lock cockpit control into neutral position Adjust cable tension Remove system locks Check/adjust primary stop Chick/adjust secondary stops

Question 48

What basic equipment is required for rigging a flat control system

Answer 48

Rig pins Rigging board Protectors or Inclinometer Rigging fixtures Contour templates Rulers Tensiometers and cable rigging tension charts

Question 49

When must a duplicate inspection be carried out

Answer 49

After any disturbance of a flight control system

Question 50

What can backlash in a control system cause

Answer 50

Flutter

Question 51

What prevents the stationary swashplate from rotating with the rotorshaft

Answer 51

Antidrive link

Question 52

How would you determine whether an access panel was a stressed panel or not

Answer 52

In the aircraft maintenance manual / panel chart

Question 53

What usually takes the presurisation loads on outward opening cargo doors

Answer 53

Hinges and latches

Question 54

What a light aircraft windows usually constructed from

Answer 54

Single layer of perplex or polycarbonate

Question 55

What can cause crazing on a plastic window

Answer 55

Mechanical stresses or the action of a chemical agent

Question 56

Describe the construction of aircraft interior partitions

Answer 56

Composites, honeycomb materials, very lightweight and non structural (to aircraft)

Question 57

What aircraft must carry a first aid kit

Answer 57

All aircraft with 10 or more passengers

Question 58

What aircraft must carry a readily accessible axe

Answer 58

Aircraft with seating capacity of 20 or more passengers

Question 59

What is the stipulation for the requirement of lifejackets

Answer 59

All flights that cannot maintain more than 1000ft altitude at more than gliding distance from the shore

Question 60

How many cabin crew should there be on board

Answer 60

1 per 50 passengers

Question 61

What is portable water

Answer 61

Water suitable for human consumption

Question 62

How is the portable water system pressurized

Answer 62

Engine bleed air

Question 63

If the recirculating pump on a recirculating toilet fails can the toilet still be used

Answer 63

Can still be used as a chemical toilet

Question 64

If waste tank is full in a vacuum toilet system, how is flush cycle prevented

Answer 64

Point level sensor prevents flush cycle if full

Question 65

How is overfilling of the portable water system prevented when servicing

Answer 65

Excess water flows through overflow fitting