Wood Structures/Fabric Covering/Painting + Finishing Flashcards
The negative aspect of wood structures:
Can rot and mildew
Positive aspects of wood structures:
Can support its own weight.
Hardens over time.
Where is rot most likely to occur on a wood structure aircraft?
In the lowest points.
T/F
Absolutely no rot is allowed on a wooden aircraft structure.
True.
Absolutely none.
Ways to detect rot:
Smell first, then visual.
Pierce with knife.
Where does the strength of wood lie?
Across the grain.
What is the wood by which all other woods’ characteristics are judged?
Sitka spruce is the reference wood.
Minimum number of rings allowed per square inch in aircraft wood:
6 rings.
Maximum slope of grain deviation in aircraft wood:
1” : 15”
Main way that wood structures are held together:
Glue
If glue fails what can be done?
Reapply glue.
What type of glue is used in wood structure?
Epoxy glue
What should be the goal of a glued joint?
To be stronger than the wood itself.
T/F
Joined portions of wooden parts should not be sanded.
True.
The grain of the different layers of plywood are _______.
Perpendicular to each other.
The grain of the different layers of laminated wood are ________.
In the same direction.
In which direction should the grain of a wood repair be?
Same direction as the part being repaired.
The purpose of any repair is to restore ________.
Strength.
Stiffness.
Shape.
What non-destructive method is used to test the deterioration limit of fabric covering?
A maule fabric tester pushed into fabric at a specified pressure.
What is the deterioration limit?
No less than 70% of original strength.
Two categories of fabric covering:
Organic.
Non-organic.
Types of organic fabric:
Cotton.
Linen.
Types of non-organic fabric:
Dacron.
Ceconite.
Superflite.
Poly-fiber.
Grades of cotton fabric:
Grade A.
Intermediate.
Glider cloth.
Material by which all organic fabrics are judged:
Grade A cotton
What factors must be considered when choosing the type of fabric?
Wing loading in pounds per square foot.
Never exceed speed (Vne)
What is used to tighten organic fabric over the structure?
Butyrate dope.
What factors must be considered to determine the spacing of fabric lacing?
In or out of prop wash.
Never excess velocity.(Vne)
What type of knot is most generally used for rib stitching?
Modified Seine knot.
How is non-organic fabric tightened on the structure?
Apply cement and filling material followed by heating.
Purposes of paint:
Prevents corrosion.
Aerodynamically clean.
Weather resistant.
What must be done to original paint before repainting?
Remove original paint to prevent weight increase.
Most common type of primer:
Epoxy primer.
What is used as a spot primer?
Zinc chromate.
What happens if wash primer is not allowed to cure properly?
Filiform corrosion will form.
_____ slows down the rate of evaporation of dope.
Retarder.
Used to restore resilience to old dope film and repair ring worming:
Rejuvenator
Types of finishing problems:
Poor adhesion.
Blushing.
Pinholes.
Orange peel.
Fisheyes.
Runs and sags.
Dope roping.
Ringworms.
What dictates spray pattern of a spray gun?
Wing port position.
Air pressure.
How far from the surface should the spray gun be held?
6”-10”
What shape indicates a correct spray pattern?
Long thin oval.
Insufficient spray gun air pressure is indicated by what shape spray pattern?
Short, more circular oval.
Trade names of fabric made from polyester fibers:
Ceconite.
Superflite.
Poly-Fiber.
3 requirements of wood used in aircraft:
12% moisture content.
Min. of 6 rings per inch.
Max. of 1:15 slope of grain.
Possible wood defects:
Cross grain.
Wavy grain.
Knots.
Pin knot clusters.
Pitch pockets.
Mineral streaks.
Technique of cutting a log to produce planks with vertical grain.
Quartersawing wood.
T/F
Flat grain is desirable for aircraft wood planks.
False.
Vertical grain.
Grain that is @45 degrees or more to the wide dimension of the wood plank.
A small plate attached to two or more members of a truss structure:
Gusset
A joint in a wood structure in which the ends to be joined are cut in a long taper.
Scarf joint
What is required by the FAA when re-covering an aircraft?
Form 337 for major repair.
What form is required when changing the fabric type on an aircraft?
STC (supplemental type certificate)
The fabric tester that actually pierces the fabric during the test:
Seyboth fabric tester
Two basic types of dopes:
Nitrate.
Butyrate.
The material placed over the ribs before lacing:
Reinforcing tape.
Material placed and doped over rib lacing:
Surface tape.
Technique that prevents fabric raveling and provides additional surface area:
Pinking. (Pinked edges)
Major drawback of nitrate dope:
Very flammable
Three types of finishing systems:
Acrylic lacquer.
Synthetic enamel.
Polyurethane. (Most used)
First coat of finishing material:
Tack coat
Where are the requirements for color and placement of registration numbers found?
FAR Part 45
ATA code for placards and markings.
ATA 11
Each pass of the spray gun should overlap all but ____ or ____inches of the previous pass.
2, 3
