Wood Preparation and Aircraft Construction Flashcards
What four time periods are critical to the bonding process of almost all types of adhesives?
1.Pot Life 2.Open assembly time 3.Closed assembly time 4.Pressing time
The basic criterion for any aircraft repair is that the repaired structure must only be as strong as the original structure, but the (?)
of the structure and the (?)
shape must also be equivalent.
a. Rigidity b. Aerodynamic
List 7 of the most common types of wooden spars.
- Solid wood rectangular wood spar 2. Solid wood routed I-beam spar 3. Laminated internally routed box spar 4. Laminated spar horizontal 5. Laminated spar vertical 6. Built up box spar 7. Built up I-beam 8. Built up C-spar
In a solid wood structure (not a spar), what minimum bevel angle is required for a scarf splice joint
1-10 or 1-12
What are the three most important requirements for a strong and durable structural bond?
Preparation Utilization Performing
Wood preparation
Cleaning with Naphtha gas is recommended. Sandpaper should never be used as sand can contaminate the wood.
Signs of fungus attack on wood product
Include softness, swelling when wet, excessive shrinkage when dry, cracking, discoloration, and a musty or moldy smell.
What causes compression failures (i.e., cracks in a wooden structure)?
Wrinkles or streaks across the grain line caused by mechanical stress on the wood after the annual rings have grown.
What can the density of wood best be described as?
Weight per unit volume of a substance.
What type of wooden spar carries the greatest loads of any of the wooden spars?
Built up wooden box spar
What are the maximum splices allowed on a wing spar?
2 Maximum.
A built-up I-beam spar repair requires a (?)
scarf joint between the original spar and new material
10 to 1 or 12 to1
Should you sand a wooden joint before you apply the adhesive (glue) to a repaired joint in a wooden aircraft structure?
Question 18 options:
a)
Yes
b)
No
No
Where on an aircraft wooden structure must drain grommets be placed in the wing area?
All wings must incorporate drainage grommets at the lowest part of each rib bay to drain accumulated moisture
Kiln
Reduces moistures and kills insect and decay producing organism.
Slope of the grain
A deviation of 1:15 is allowed. The slope of the grain must not be steeper than 1:15.
Sitka spruce
The most common type of wood used in aircraft construction.
Three most common forms of wood used in aircraft construction
Solid wood, Plywood, Laminated wood.
Ideal moisture content for serviceable aircraft wooden structures
Between 8% and 16%, with an ideal range of 10% to 12%.
To make sure annual growth rings are at the correct angle to the wide face, at what angle are quarter-sawn wood cut from quartered logs?
45 degrees
It is important to observe the orientation of the wood grain to avoid applying glue to the end grain. In relation to the direction of the grain, at what degree is end grain wood cut?
90 degrees
List 5 reasons why wood is used in aircraft.
Attributes similar to that of metal and composites
Light weight
low cost
High strength
Minimum of special tools and equipment to maintain and repair
What should be the specific gravity of aircraft wood? What should be the specific gravity of aircraft spruce?
From 0.34 to 0.40; 0.36
What is the grain deviation or slope allowed in aircraft construction?
1:15.
What 8 defects are not allowed in aircraft wooden structures?
- Cross grain
- Wavy, curly, and interlocked grain
- Hard knots
- Pine knot clusters
- Spike knots
- Pitch pockets
- Mineral streaks
- Checks, shakes, and splits.
What 5 defects may be acceptable depending on their size, location and condition?
1 Cross grain
2 Wavy, curly, and interlocked grain
3 Hard knots
4 Pine knot clusters
5 Pitch pockets
For wing spars repair it is necessary to use?
Always use the manufactures repair instructions when available
Scarfed Patch is what?
This is the most desired skin patch as it makes the least change in skin thickness or rigidity
Since most adhesives will not bond satisfactorily to sealers, it is necessary to avoid applying sealer over the areas where adhesive will be applied. when doing this it is important to?
Mask off areas to receive adhesive, and allow an additional ¼inch on each side of the adhesive area to provide for misalignment when mating the parts.
Sealing of bolt heads?
The sealer must be allowed to dry or cure thoroughly
5 types of Inspection Methods
1.Tapping 2.Probing 3.Prying 4.Smelling 5.Visual
Mineral lines are acceptable true or false
true
Reddish streaks are common in Sitka spruce due to?
Due to Deposit in ray cells. They do not affect the quality of the wood
Specific Gravity of A/C grade wood should be from
0.34 to 0.40, Ideal is 0.36
