6.3 Fabric Covering Flashcards
What must be done before any aircraft is covered
The structure must be inspected
What are the most suitable conditions for applying fabric
Room temperature 16-21°c relative humidity no more than 70%
What are linen tapes for
Covering leading edges
What is Egyptian tape used for
Used on members where chafing occurs
What is Egyptian tape also known as
Cotton tape
What conditions must aircraft materials get stored
At 20°c in a dry cool place away from direct sunlight
For areas where serious chafing may occur, what can be done to prevent this
A reinforcement is used in the form of a canvas or leather patch
What is used to make sure that dope doesn’t react with surface protections
The structure is covered with aluminium tape or adhesive cellulose or painted with dope resistant white paint
What are the 2 ways of recovering wooden aircraft
- Prefabricared envelopes
- The Blanket method
When recovering aircraft, where should seams not be placed
Should never be at right angles to the direction of the airflow
What is the balloon seem also known as
The French fell
Why is the balloon seem or French fell examined with a light after sewing
To make sure that all seams have been done correctly
When should the lap seam be used
Only when specified by the manufacturer
What stitch forms are used for repair work
- Herringbone (baseball stitch)
- Boot stitch
What 2 stitch methods are used for hand sewing
- The lock stitch
- The overhand stitch
What stitch method is used for trailing edges, wing tips and where sudden changes of direction occur
The overhand
When would beeswax be used
On all threads for hand sewing that haven’t been pre waxed
What is flax chord normally used for
For stringing purposes and is normally applied in single strands
When is boom stringing done
On deep aerofoil sections
What happens if stringing tension is too much
It can distort the ribs
What is the slip stream area
For stringing purposes the slip stream area is considered to be the diameter of the propeller plus one rib either side
When material is fixed down (normally on a metal structure) with steel groves or channels what is it called
Special stringing
What would the procedure be for applying fabric to plywood
Wood surface should be smoothed with fine glass paper, then doped
Why is drainage and ventilation a necessity
To prevent corrosion of the structure or rot of the fabric
Where are drainage holes normally fitted
The lower or bottom parts of the structure where moisture is most likely to gather
What are drainage eyelets
They are normally circular or oval in shape and doped on to the surface of the fabric. They are sometimes stitched on.
What are shielded eyelets
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
What are the 3 forms of inspection panels
- Woods frames
- Zip panels
- Spring panels
What are woods frames
Light circular or square frames made from celluloid sheet which are doped on to the fabric covering
What are zip panels
Two zip sections sewn on to the fabric in the form of a V easy excess for inspection
What are spring panels
Particularly used on light aircraft
What sit here type should be used for repairing straight cuts or tears
The herringbone (baseball) (ladder)
What should be done to repair damage in fabric with jagged edges
Woods frame doped on place
When can repairs by darning be carried out
On irregular holes or jagged tears 50mm (2in) or smaller
What must also be done with a darning repair
The whole repair covered in a serrated in a serrated patch with an overlap of 37mm
How frequently should a lock knot be used in the boot stitch
Every 150mm (6in)
What are the names of the 2 fabric testers
Maul and seyboth
When repairing puncture holes produced by a sayboth tester what materials should be used
A 50mm or 75mm doped patch
What is important to take into consideration when using a sayboth tester
Should not be done through s double layer of fabric, this would give an inaccurate value
How does the maul fabric tester work
If the fabric has been punctured it has failed and if the fabric does not puncture it has passed
Which fabric tester has the red, yellow and green traffic light measuring scale
Seyboth tester
What are the two man made fibres used to cover aircraft
Polyester fibre and glass fibre
Which man made fabric needs to be heat shrieked into position and then doped
Polyester fibre
Which man made material needs to be cut quite accurately in the first place before doping
Glass fibre, dope only slightly taughtens it
What type of repair can be made to polyester fibre materials
Small patches may be stuck on with adhesive however laterger patches will have to be recovered like initial application
How are repairs to glass fibre materials carried out
But cutting out damage and doping on a patch which overlaps 50mm all way round
What characteristics does dope provide
- Taughtening of natural fabrics
- Waterproofing
- Airproofing
- Lightproofing
What does dope consist of
A number of resins dissolved in a solvent
How is dope applied
Normally by brushing or spraying
What are the two types of dope mainly used
- Cellulose Nitrate
- Cellulose acetate byturate
What happens with dope as it ages
It becomes acidic
What is the purpose of aluminium dope
To make the fabric light proof
What is done to dope to make it suitable for spraying
Thinners are used for spraying
What is the purpose of MEK
A low cost solvent similar to acetone for removing dirt and grease
What is sometimes added to the first layer of dope
Fungicides to help prevent mildew and fungus
What is a tack rag
A rag slightly dampened with thinners used to wipe a sanded surface before the application of the next coat
What is the main danger of working with dope
The vapours are heavier than air and are easily ignited
What is the most common cause of a spark when working with dope
Static electricity
What is the best way to prevent static electricity when working with dope
To ground or earth the structure your working on
The storage and usage of dope is covered by various government regulations under what act
The factories act
What must be done when spraying nitrate dope
The gun and the person spraying must be grounded
How should the floors be swept when in the spray shop
They should be well doused with water and then swept when still wet
What should dope not be mixed with
Electrical drills
What type of working conditions must be had when using or spraying dope
Good regulation of humidity
Good regulation of temperature
Good airflow
What must be installed in the floor of a spray shop
An explosion proof fan to prevent heavy vapours from collecting at floor level
What is the optimum temperature for spraying dope
21-26°c
What is the desirable range of humidity for spraying dope
Between 45-50% however 20-70% can be ok
What should the humidity of a spray room be measured with
A hygrometer
What is the most common way for measuring humidity of a spray room
The wet and dry bulb type
What must be done when the aircraft has been doped and painted
It must be re weighed
