Wood Structures Flashcards

1
Q

How would you inspect wood for rot (decay)?

A

Inspect for a dark discoloration of the wood surface or gray stains along the grain.

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2
Q

What three forms of wood are used in aircraft?

A

Solid, Laminaded and Plywood.

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3
Q

What is a laminated wood assembly?

A

Two or more layers glued together with the grain of all layers approximately parallel.

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4
Q

How is aircraft plywood constructed?

A

Made of an odd number of thin plies, and the grains of each layer, placed 90° with the adjacente ply or plies.

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5
Q

What specie of wood is used as a standard for strenght?

A

Spruce

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6
Q

Are hard knots acceptable?

A

Yes, within specified limits.

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7
Q

Why is compression wood NOT acceptable?

A

It is very prejudicial to strength.

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8
Q

When are mineral streaks acceptable?

A

If the inspection fails to reveal any decay.

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9
Q

Why is it necessary to examine all strains and discoloration?

A

To determine if the stains are harmless, preliminar or advanced decay.

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10
Q

What types of glues are used in aircraft wood structure repair?

A

Casein, Epoxies, Phenol-formaldehyde, Resorcino/ Glue.

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11
Q

What type of glue may have been used in OLDER AIRCRAFT construction that requires careful inspection to detect deterioration?

A

Casein Glue.

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12
Q

What types of glues are used in MODERN AIRCRAFT wood structure repair?

A

Resorcinol glue, Phenol-formaldehyde glue and Epoxi resin glue.

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13
Q

What is the minimum °F for curing wood joints with resin glue?

A

70°F or as specified by the glue manufacturer.

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14
Q

Why it is important to consider the open-assembly time when gluing wooden structures?

A

Because if the maximum open-assembly time is exceeded the joint may fail since the glue my begin setting up before the joint is assembled.

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15
Q

Why it is important to apply the proper clamping pressure to a glue joint?

A

Clamping forces the air out, brings the wood surfaces together evenly and in part responsible for the strength of the glue line

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16
Q

Describe the acceptable methods used to repair enlongated bolt holes found in a wooden wing spar:

A

Remove the damaged section and splice in a new section or replace the entire spar.

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17
Q

Describe the characteristics of a scarf joint:

A

The pieces to be joint are tapered or beveled on a slope of 1 to 10 or 1 to 12.

18
Q

What are the results of insuficient gluing pressure?

A

Thick glue and a weak joint.

19
Q

What methods are used to apply pressure to wood glue joints?

A

Clamps, Brads, Nails, Elastic Straps, Weight, Vacuum Bags, Screws, Electric and Hydraulic power presses.

20
Q

What type of joint is used in splicing structural members?

A

A Scarf Joint.

21
Q

What areas of a wood spar may NOT be spliced?

A

Under a wing attachment, landing gear, engine mount and lift strut fittings.

22
Q

What are the two primary uses for plywood in aircraft construction?

A

Gusset plates and aircraft skin.

23
Q

Provide examples of at least three types of plywood skin repair:

A

Scarf, surface, plug, splayed and scarfed patches.

24
Q

What type of patch should be used to repair small holes in thin plywood skinif the skin is less than 1/1 inch thick?

A

A splayed patch.

25
Q

Why must the beveled cut accurate on both pieces of wood being repaired with a scarfed joint?

A

The pieces must match exacly to ensure a tight glue joint

26
Q

Name at least three diferent types of defects found in wood:

A

Knots, checks, decay, Splits, pitch pockets, curly grain, cross grain, dry rot.

27
Q

Why should the various pieces of wood be kept in a room for at least 24 hours prior to joining?

A

To allow the moisture content to equalize, minimizing dimensional changes in the wood.

28
Q

What is the maximum number of splices that should be made to any one spar?

A

Two.

29
Q

Always splice and reinforce plywood webs with what type of wood?

A

The same type of plywood as the original.

30
Q

Why are light steel bushings somethimes used in wooden structures?

A

To prevent crushing the wood when the bolts are tightened.

31
Q

What is the purpose of large surface area washers when used on wooden structures?

A

To provide additional bearing area for hardware to help preclude damage to the wood when the hardware is tightened.

32
Q

What method will prevent a patch and a plywood pressure plate from adhering together due to extruding glue from the patch?

A

The use of waxed paper or vinyl plastic between the patch and pressure plate.

33
Q

Name several facings and core material used in bonded honeycomb structures intended for special applications:

A

Stainless steel, Titanium, Magnesium, Plywood, glass, Nylon and cotton cloth.

34
Q

Describe the construction of a bonded honeycomb structure:

A

It is a laminated structure that has a solid facing bonded to either side of a core consisting of open six-sided cells.

35
Q

What must be done with a damaged area in a bonded honeycomb structure prior to beginning repairs?

A

Inspect the area, determine the damage prior removing the afected area.

36
Q

A drill bit used for drilling composites should operate at approximately what speed?

A

20.000 гр.

37
Q

What are the most common causes for delamination of a composite structure?

A

Sonic Vibration, expansion of internal moisture, liquid leakage and manufacturing error.

38
Q

What type of defect in, or damage to, a bonded honeycomb structure can be repaired using the potted repair method?

A

Filling a hole.

39
Q

Name some factors that cause crazing in transparent plastic Windows and windshields:

A

Expousure to UV, stress, improper solvents and improper handling.

40
Q

How should a hole be drilled in Plexiglas to avoid damage to the hole when the drill breaks through to the underside?

A

Backup the plastic with a piece of wood and feed the drill slowly.

41
Q

What should be done to twist drills that are to be used for drilling completely trough Plexiglas?

A

Drill free of burrs, drill angle of 150°, feed the drill slowiy.