6.3.3 Fbric Covering

Question 1

Before fabric covering any component what must be done to the structure

Answer 1

Structure must be inspected, all foreign matter removed and protective treatments must be applied

Question 2

What are the most stable temperatures for applying fabric to an aircraft

Answer 2

16-21°c and a relative humidity of no more than 70%

Question 3

What is cotton tape also referred to as

Answer 3

Egyptian tape

Question 4

What are linin tapes used for

Answer 4

Covering leading and trailing edges and repairs

Question 5

What is used for stringing

Answer 5

Flax chord

Question 6

What type of conditions should aircraft coverings be stored

Answer 6

About 20°c in the dry

Question 7

What must be done to bolt heads and screw heads that would be likely to chafe before covering

Answer 7

They should be covered with tape

Question 8

How may aircraft fabrics be fitted

Answer 8

With the warp or weft 45° to the slip stream or in line with the slip stream

Question 9

What are the most common methods of re covering aircraft

Answer 9

• Prefabricated envelopes

- The Blanket method

Question 10

How should stitching not be done

Answer 10

Seams should never be made at right angles to the direction of air flow

Question 11

What two types of machine seams are used on aircraft

Answer 11

• Balloon seam

- Lap seam

Question 12

What is the Balloon seem also referred to as

Answer 12

The French Fell

Question 13

When would the Lap seam be used

Answer 13

Only when specified for the manufacturer. The Balloon seam(French fell) is the preferred method

Question 14

What is the main hand sewing method

Answer 14

Overhand stitch

Question 15

What are the 2 types of hand stitch used for repairs

Answer 15

Herringbone (baseball)

Boot

Question 16

What should be done to all threads before sewing

Answer 16

A layer of beeswax should be applied

Question 17

What is boom stringing used for

Answer 17

Deep aerofoil sections

Question 18

How is fabric usually attached to plywood

Answer 18

It is usually done with dope

Question 19

When attaching fabric to metal surfaces, other than doping in to place what could be used

Answer 19

Alternatively a thermoplastic adhesive may be used

Question 20

What does drainage and ventilation provide for fabrics

Answer 20

Minimise corrosion of the structure and rotting of the fabric

Question 21

What shape are drainage eyelets usually

Answer 21

Oval or circular

Question 22

How are drainage eyelets applied to the structure

Answer 22

They are doped in to place, however they can also be sewn

Question 23

What is the purpose of shielded eyelets

Answer 23

Used in marine environments to prevent the entry of sea spray

They must not be used instead of regular eyelets

They must be facing the correct way

Question 24

What are the 3 methods of inspection panels which are used on wooden aircraft

Answer 24

• Woods frame
• Zip panels
• Spring panels

Question 25

What are woods frames

Answer 25

A circular or square frame made of a celluloid sheet which are doped on to the fabric cover at required positions

Question 26

What is the biggest disadvantage of the woods frame

Answer 26

A new patch has to be doped on every time

Question 27

What are zip panels

Answer 27

Consist of two zip fasteners sewn in to the fabric in the form of a vee. They are used in areas where frequent inspection is required

Question 28

What are spring panels

Answer 28

Particularly suitable for light aircraft

Question 29

What method would be used to repair a fabric that has been damaged extensively

Answer 29

If the fabric is damaged extensively it should not be repaired and should be replaced

Question 30

When should the herringbone stitch be used

Answer 30

Should be used when repairing straight cuts or tears which have sound edges. After the stitching has been completed, 25mm wide serrated tape should be doped over the stitching

Question 31

What is the other method of fabric repair if the herringbone is not permitted to be used

Answer 31

Woods frame method

Question 32

What is darning

Answer 32

Irregular holes or jagged tears in fabric may be repaired by darning provided that the hole is no bigger than 50mm wide at any point

Question 33

What is used for damage over 100mm wide

Answer 33

Square insertion repairs are normally used

Question 34

What is a boot stitch

Answer 34

Used for repairs, requires a lock knot every 150mm (6 inches)

Question 35

What are the 2 portable fabric testers

Answer 35

- Maule | - Seyboth

Question 36

What is the maule tester

Answer 36

If the tester has penetrated the fabric then the fabric has failed the test

Question 37

What is the seyboth tester

Answer 37

Always pierce the fabric Colour scale Make sure not on double width fabric All holes must be doped closed

Question 38

What man made fabrics replace natural fabrics used on aircraft

Answer 38

- Polyester fibre materials | - Glass fibre materials

Question 39

What is done to polyester fibre materials to apply them to structures

Answer 39

They are toughened by heat. (Usually and iron at 120°c)

Question 40

How is glass fibre applied to an aircraft

Answer 40

Can only be slightly toughened by dope so it must be a good initial fit

Question 41

What are the functions of dope

Answer 41

- Toughening of natural fabrics - Waterproofing - Airproofing - Light proofing

Question 42

What are the 2 different types of dopes used

Answer 42

- Cellulose nitrate | - Cellulose acetate butyrate

Question 43

Why is aluminium dope sometimes used

Answer 43

To protect the fabric from sunlight (UV)

Question 44

What is Methylethyl-Ketone (MEK) used for

Answer 44

It is a relatively low cost solvent, similar to acetone. It is widely used for a cleaning agent and to remove dirt or wax prior to doping

Question 45

What is normally added to the first layer of dope

Answer 45

A fungicide to prevent the growth of fungus

Question 46

What are the main hazards of dopes

Answer 46

Very flammable Low flash point Accumulation of vapours can ignite easily

Question 47

What is the most common cause of dope ignition

Answer 47

The discharge of static electricity

Question 48

What must be done to prevent the build up of static discharge when doping an aircraft

Answer 48

The aircraft should be grounded

Question 49

What is the bet way airflow is regulated when doping an aircraft

Answer 49

A fan should be installed at floor level and the fan should be explosion proof

Question 50

For applying dopes what temperature range is prime and shouldn't really be exceeded

Answer 50

Between 21°c and 26°c

Question 51

What is the ideal humidity required when doping

Answer 51

Between 45-50% however anything from 20-70% is acceptable

Question 52

What is the most common way of measuring humidity

Answer 52

Wet bulb dry bulb method

Question 53

What are priming coats

Answer 53

The first coats applied to a fabric