Chapter 6 Aircraft Wood
B
A faint line running across the grain of a wood spar generally indicates A) shear failure. B) compression failure C) decay.
water penetration
Dark discolorations of the wood or grey stains is signs of
Splayed Patch
Kind of patch that is flush, slope cut at a 5:1 Ratio to the thickness of the skin. May be used for small holes where the largest dimension of the hole to be repaired is not more than 15 times the skin thickness and the skin is not more than 1/10 inch thick.
C
Laminated wood is sometimes used in the construction of highly stressed aircraft components. This wood can be identified by its A) similarity to standard plywood construction. B) perpendicular grain construction. C) parallel grain construction.
B
Laminated wood spars may be substituted for solid rectangular wood spars A) only upon specific approval by the manufacturer or the FAA. B) if the same quality wood is used in both. C) only in certain instances where the primary load is shared by one or more other original structural member.
Spruce Goose
Largest aircraft made of wood was the:
Two
No more then _____ Splices should be made in any one spar.
5:1
On a wing spar repair, the slope of the scarf should not be steeper then:
B
The strength of a well designed and properly prepared wood splice joint is provided by the A) bearing surface of the wood fibers. B) glue. C) reinforcement plates.
200 PSI
This pressure range must be applied when gluing hardwoods
10-150 PSI
This pressure range must be applied when gluing softwoods
Glue Joint Test
This process is uses scrap pieces of wood then glued and broken to see if the strength of the glue is correct and can be used.
Plug Patch's
Two types of ____ _________ are: Oval patch, and round and may be used on plywood skins. Because this is only a skin repair, use it only for damage that does not involve the supporting structure under the skin.
Guide Board
Ways to prevent a wood blowout when cutting is to use a
corrosion
Ways to tell if the wood has water penetration, screws when removed will have
Scarf Patch
What kind of repair is recommended for a hole in the plywood skin of an aircraft wing?
A
When and how is finishing tape applied on a fabric covered aircraft? A) Doped on after the first or second coat of dope. B) Doped on immediately prior to the finish coat. C) Sewed or laced on before dope is applied.
Drill Press
When boring accurate smooth holes, it is recommended that a _________ __________ be used.
Smaller then bolt diameter
When drilling a hole for a bolt to be inserted into laminated glue joints, the hole should be __________________________________ so it requires a light tap to insert it using a rawhide or wooden mallet.
one size
When installing a new screw into a wooden surface, the screw should be _____ _________ bigger.
C
When patching a plywood skin, abrupt changes in cross sectional areas which will develop dangerous stress concentration should be avoided by using A) square patches. B) doublers with any desired shaped patches. C) circular or elliptical patches.
Manufactures Manuals
When starting a repair on a wooden aircraft structure, you must consult with the ______________________ _____________ and instructions. If not available, check FAA (AC) 43.13-1 for acceptable methods.
Good Glue Joint
When testing wood glue, when the wood brakes on the surface the glue is used on this determines a:
C
Where is information found concerning acceptable species substitutions for wood materials used in aircraft repair? A) Aircraft Specifications or Type Certificate Data Sheets. B) Technical Standard Orders. C) AC 43.13-1B.
A
Which of the following conditions will determine acceptance of wood with mineral streaks? A) Careful inspection fails to reveal any decay. B) They produce only a small effect on grain direction. C) Local irregularities do not exceed limitations specified for spiral and diagonal grain.
C
Which statement about wood decay is correct? A) Decay that occurs before the wood is seasoned does not affect the strength of the finished piece. B) A limited amount of certain kinds of decay is acceptable in aircraft woods since decay affects the binding between the fibers and not the fibers themselves. C) Decay is not acceptable in any form or amount.
Caul
a clamping device, usually two rigid wooden bars, to keep an assembly of flat panel boards aligned during glue-up.
Close contact adhesive
a non-gap-filling adhesive (e.g., resorcinol-formaldehyde glue) suitable for use only in those joints where the surfaces to be joined can be brought into close contact by means of adequate pressure, to allow a glue line of no more than 0.005- inch gap.
Gap-Filling Adhesive
an adhesive suitable for use in those joints in which the surfaces to be joined may not be close or in continuous contact (e.g., epoxy adhesives) due either to the impracticability of applying adequate pressure or to the slight inaccuracies of fabricating the joint.
Double Spread
spread of adhesive to both surfaces and equally divided between the two surfaces to be joined.
Single Spread
spread of adhesive to one surface only.
Pressing Or Clamping Time
time during which the components are pressed tightly together under recommended pressure until the adhesive cures (may vary from 10 to 150 pounds per square inch (psi) for softwoods, depending on the viscosity of the glue).
Adhesive Pot Life
time elapsed from the mixing of the adhesive components until the mixture must be discarded, because it no longer performs to its specifications. The manufacturer's product data sheet may define this as working time or useful life; once expired, the adhesive must not be used.
Closed Assembly Time
time elapsing between the assembly of the joints and the application of pressure.
B
Compression failures in wood aircraft structures are characterized by buckling of the fibers that appear as streaks on the surface A) at right angles to the growth rings. B) at right angles to the grain. C) parallel to the grain.
2 inches
The patch should be covered with fabric that overlaps the original surface by at least ____ _________
5 times
The radius of corners must be ___ _______ the skin thickness
15 to 1
The slope of the scarf in any stressed part, such as a spar, should not be steeper than ___ __ ____.
air bubbles, foam, and lumps
Adhesive and glues must be mixed slowly to prevent
1:15
Aircraft grain slope cant be greater then?
Spruce, Douglas fir, and Noble fir
Best species of wood for aircraft construction are?
6A to 5A
During a splice repair of a solid rectangular spar, the distance from the spar cut to the slope of the spar is recommended to be ____ ___ _____ recommended.
C
Glue deterioration in wood aircraft structure is indicated A) when a joint has separated and the glue surface shows pieces of wood and/or wood fibers clinging to the glue. B) by any joint separation. C) when a joint has separated and the glue surface shows only the imprint of the wood with no wood fibers clinging to the glue.
engineering
If instructions are not available for a specific type of repair, it is highly recommended that you request appropriate __________________ assistance to evaluate and provide guidance for the intended repair.
B
In cases of elongated boltholes in a wood spar or cracks in the vicinity of boltholes, A) the spar may be reinforced by using hardwood reinforcing plates. B) a new section of spar should be spliced in or the spar replaced entirely. C) it is permissible to ream the hole, plug with hardwood, and redrill.
C
Pin knot clusters are permitted in wood aircraft structure provided A) they have no mineral streaks. B) no pitch pockets are within 12 inches. C) they produce a small effect on grain direction.
Surface Patch
Plywood skins not over 1 ⁄8-inch thick that are damaged between or along framing members may be repaired with a _____________ or overlay patch.
8-12%
Proper and equal moisture content of wood to be joined
A
The I beam wooden spar is routed to A) reduce weight. B) obtain uniform strength. C) increase strength.
A
The cantilever wing uses A) no external bracing. B) external struts or wire bracing. C) the skin to carry most of the load to the wing butt.
Open assembly time
period of time between the application of the adhesive and the assembly of the joint components.
