6.3 Fabric Covering

Question 1

What must be done before any aircraft is covered

Answer 1

The structure must be inspected

Question 2

What are the most suitable conditions for applying fabric

Answer 2

Room temperature 16-21°c relative humidity no more than 70%

Question 3

What are linen tapes for

Answer 3

Covering leading edges

Question 4

What is Egyptian tape used for

Answer 4

Used on members where chafing occurs

Question 5

What is Egyptian tape also known as

Answer 5

Cotton tape

Question 6

What conditions must aircraft materials get stored

Answer 6

At 20°c in a dry cool place away from direct sunlight

Question 7

For areas where serious chafing may occur, what can be done to prevent this

Answer 7

A reinforcement is used in the form of a canvas or leather patch

Question 8

What is used to make sure that dope doesn’t react with surface protections

Answer 8

The structure is covered with aluminium tape or adhesive cellulose or painted with dope resistant white paint

Question 9

What are the 2 ways of recovering wooden aircraft

Answer 9

• Prefabricared envelopes

- The Blanket method

Question 10

When recovering aircraft, where should seams not be placed

Answer 10

Should never be at right angles to the direction of the airflow

Question 11

What is the balloon seem also known as

Answer 11

The French fell

Question 12

Why is the balloon seem or French fell examined with a light after sewing

Answer 12

To make sure that all seams have been done correctly

Question 13

When should the lap seam be used

Answer 13

Only when specified by the manufacturer

Question 14

What stitch forms are used for repair work

Answer 14

• Herringbone (baseball stitch)

- Boot stitch

Question 15

What 2 stitch methods are used for hand sewing

Answer 15

• The lock stitch

- The overhand stitch

Question 16

What stitch method is used for trailing edges, wing tips and where sudden changes of direction occur

Answer 16

The overhand

Question 17

When would beeswax be used

Answer 17

On all threads for hand sewing that haven’t been pre waxed

Question 18

What is flax chord normally used for

Answer 18

For stringing purposes and is normally applied in single strands

Question 19

When is boom stringing done

Answer 19

On deep aerofoil sections

Question 20

What happens if stringing tension is too much

Answer 20

It can distort the ribs

Question 21

What is the slip stream area

Answer 21

For stringing purposes the slip stream area is considered to be the diameter of the propeller plus one rib either side

Question 22

When material is fixed down (normally on a metal structure) with steel groves or channels what is it called

Answer 22

Special stringing

Question 23

What would the procedure be for applying fabric to plywood

Answer 23

Wood surface should be smoothed with fine glass paper, then doped

Question 24

Why is drainage and ventilation a necessity

Answer 24

To prevent corrosion of the structure or rot of the fabric

Question 25

Where are drainage holes normally fitted

Answer 25

The lower or bottom parts of the structure where moisture is most likely to gather

Question 26

What are drainage eyelets

Answer 26

They are normally circular or oval in shape and doped on to the surface of the fabric. They are sometimes stitched on.

Question 27

What are shielded eyelets

Answer 27

They are used in special positions to help improve drainage or ventilation They are used on marine aircraft to prevent the entry of sea spray They must not be used as an alternative to normal eyelets They need to be facing the correct way otherwise they won’t be effective

Question 28

What are the 3 forms of inspection panels

Answer 28

- Woods frames - Zip panels - Spring panels

Question 29

What are woods frames

Answer 29

Light circular or square frames made from celluloid sheet which are doped on to the fabric covering

Question 30

What are zip panels

Answer 30

Two zip sections sewn on to the fabric in the form of a V easy excess for inspection

Question 31

What are spring panels

Answer 31

Particularly used on light aircraft

Question 32

What sit here type should be used for repairing straight cuts or tears

Answer 32

The herringbone (baseball) (ladder)

Question 33

What should be done to repair damage in fabric with jagged edges

Answer 33

Woods frame doped on place

Question 34

When can repairs by darning be carried out

Answer 34

On irregular holes or jagged tears 50mm (2in) or smaller

Question 35

What must also be done with a darning repair

Answer 35

The whole repair covered in a serrated in a serrated patch with an overlap of 37mm

Question 36

How frequently should a lock knot be used in the boot stitch

Answer 36

Every 150mm (6in)

Question 37

What are the names of the 2 fabric testers

Answer 37

Maul and seyboth

Question 38

When repairing puncture holes produced by a sayboth tester what materials should be used

Answer 38

A 50mm or 75mm doped patch

Question 39

What is important to take into consideration when using a sayboth tester

Answer 39

Should not be done through s double layer of fabric, this would give an inaccurate value

Question 40

How does the maul fabric tester work

Answer 40

If the fabric has been punctured it has failed and if the fabric does not puncture it has passed

Question 41

Which fabric tester has the red, yellow and green traffic light measuring scale

Answer 41

Seyboth tester

Question 42

What are the two man made fibres used to cover aircraft

Answer 42

Polyester fibre and glass fibre

Question 43

Which man made fabric needs to be heat shrieked into position and then doped

Answer 43

Polyester fibre

Question 44

Which man made material needs to be cut quite accurately in the first place before doping

Answer 44

Glass fibre, dope only slightly taughtens it

Question 45

What type of repair can be made to polyester fibre materials

Answer 45

Small patches may be stuck on with adhesive however laterger patches will have to be recovered like initial application

Question 46

How are repairs to glass fibre materials carried out

Answer 46

But cutting out damage and doping on a patch which overlaps 50mm all way round

Question 47

What characteristics does dope provide

Answer 47

- Taughtening of natural fabrics - Waterproofing - Airproofing - Lightproofing

Question 48

What does dope consist of

Answer 48

A number of resins dissolved in a solvent

Question 49

How is dope applied

Answer 49

Normally by brushing or spraying

Question 50

What are the two types of dope mainly used

Answer 50

- Cellulose Nitrate | - Cellulose acetate byturate

Question 51

What happens with dope as it ages

Answer 51

It becomes acidic

Question 52

What is the purpose of aluminium dope

Answer 52

To make the fabric light proof

Question 53

What is done to dope to make it suitable for spraying

Answer 53

Thinners are used for spraying

Question 54

What is the purpose of MEK

Answer 54

A low cost solvent similar to acetone for removing dirt and grease

Question 55

What is sometimes added to the first layer of dope

Answer 55

Fungicides to help prevent mildew and fungus

Question 56

What is a tack rag

Answer 56

A rag slightly dampened with thinners used to wipe a sanded surface before the application of the next coat

Question 57

What is the main danger of working with dope

Answer 57

The vapours are heavier than air and are easily ignited

Question 58

What is the most common cause of a spark when working with dope

Answer 58

Static electricity

Question 59

What is the best way to prevent static electricity when working with dope

Answer 59

To ground or earth the structure your working on

Question 60

The storage and usage of dope is covered by various government regulations under what act

Answer 60

The factories act

Question 61

What must be done when spraying nitrate dope

Answer 61

The gun and the person spraying must be grounded

Question 62

How should the floors be swept when in the spray shop

Answer 62

They should be well doused with water and then swept when still wet

Question 63

What should dope not be mixed with

Answer 63

Electrical drills

Question 64

What type of working conditions must be had when using or spraying dope

Answer 64

Good regulation of humidity Good regulation of temperature Good airflow

Question 65

What must be installed in the floor of a spray shop

Answer 65

An explosion proof fan to prevent heavy vapours from collecting at floor level

Question 66

What is the optimum temperature for spraying dope

Answer 66

21-26°c

Question 67

What is the desirable range of humidity for spraying dope

Answer 67

Between 45-50% however 20-70% can be ok

Question 68

What should the humidity of a spray room be measured with

Answer 68

A hygrometer

Question 69

What is the most common way for measuring humidity of a spray room

Answer 69

The wet and dry bulb type

Question 70

What must be done when the aircraft has been doped and painted

Answer 70

It must be re weighed