Chap 13: Plastic window and windshield repair

Question 1

types of plastics and its properties

Answer 1

thermoplastics: (transparent clear plastic)
shaped and formed after softening with heat
retain their structural strength when cooled
used for windshields, landing-light covers

thermosetting plastics:
after heating and cooling down becomes hardened
cannot be softened and reset again by further heating

Question 2

2 types of clear plastics

Answer 2

acrylics

cellulose acetates

Question 3

clear plastic are tinted to?

Answer 3

tinted to a certain degree to reduce light penetration

light pen. through windshield into cockpit

Question 4

advantages and disadvantages of plastic over glass

Answer 4

advantages:
lighter in weight
no reduction in clarity
more resistant to breakage
safer as dull edges are produced when broken

disadvantages:
attract dust and dirt due to static discharge
softer than glass (more prone to surface abrasion damage)

Question 5

4 types of plastic repair process

Answer 5

cutting
drilling
cementing
annealing

Question 6

cutting plastic repair description

Answer 6

avoid unnecessary localised stressing to prevent cracking of plastic
provide allowances when laying the cutting guidelines
use coolant when cutting thick plastic (prevent molten plastic on blade)

Question 7

drilling plastic repair description

Answer 7

use coolant when drilling holes

support thin plastic with wooden block to prevent breaking of plastic when drill through

Question 8

cementing plastic repair description

Answer 8

use of adhesive to join mating plastic parts together (methylene chloride)
applied on mating surfaces, parts are held tgt under pressure until cement sets
heating joint areas increases strength (forcing solvents out of plastic)

Question 9

annealing plastic repair description

Answer 9

formed plastic to be annealed before cementing
relieves internal stress and improve resistance to crazing
acrylics are annealed by soaking at high temp. and cooling down slowly

Question 10

crack repair using surface patch method

Answer 10

1) stop-drill crack and reinforce with surface patch (same material)
2) patch should extend beyond edges of crack by 3/4 in. (1.91cm) minimum
3) apply adhesive on patch and lay over the crack area under pressure
4) polish surface patch until clear after setting for 24hrs

Question 11

hole repair with surface patch method

Answer 11

1) stop-drill any radiating crack from hole
2) remove rough edges of hole (filling)
3) cover hole using surface patch method (use adhesives + …)