quiz 2 Flashcards
Several forms of wood are commonly used in aircraft.
Solid wood
Laminated wood
Plywood
High-density material
” refers to a member
consisting of one piece of wood.
Solid wood or the adjective “solid” used with such
nouns as “beam” or “spar
is an assembly of two or more layers
of wood that have been glued together with the grain
of all layers or laminations approximately parallel.
Laminated wood
Laminated wood is an assembly of two or more layers
of wood that have been glued together with the grain
of all layers or____________ approximately parallel.
laminations
is an assembled product of wood and glue
that is usually made of an odd number of thin plies, or
veneers, with the grain of each layer placed 90° with
the adjacent ply or plies
Plywood
Plywood is an assembled product of wood and glue
that is usually made of an odd number of thin plies, or
veneers, with the grain of each layer placed ____ with
the adjacent ply or plies
90°
used as bearing or reinforcement plates.
High-density material
High-density material includes
compreg, impreg, or
similar commercially made products, heat-stabilized
wood, or any of the hardwood plywoods
is the preferred choice and the standard
by which the other wood is measured
Spruce
one item common to all the
species is that the slope of the grain cannot be steeper
than _________.
1:15
All solid wood and plywood used for the construction and
repair of aircraft should be of the ___________-
highest quality and grade
For certificated aircraft, the wood should have traceability to a
source that can provide certification to a___________.
military specification
(MIL-SPEC)
MIL-SPEC meaning
military specification
is referred to and specified in some repair documents, but
that grade wood cannot be purchased from a local lumber
company.
“aircraft quality” or “aircraft grade”
To purchase the material, contact one of the specialty aircraft supply companies and request a _______.
certification
document with the order
The MIL-SPEC for solid spruce is
1.______ and for plywood it is 2.______.
1.MIL-S-6073
2.MIL-P-6070B
When possible, fabricated wood components should be
purchased from the 1._______, or someone
who may have a 2._________ to
produce replacement parts for the aircraft.
1.aircraft manufacturer
2.Parts Manufacturer Approval (PMA)
Excellent for all uses. Considered standard
Spruce (Picea)
Sitka (P. sitchensis)
Red (P. rubra)
White (P. glauca)
there Strength Properties (compared to spruce) is 100%
Spruce (Picea)
Sitka (P. sitchensis)
Red (P. rubra)
White (P. glauca)
Maximum
Permissible
Grain Deviation
(slope of grain)
1.15
strength properties Exceeds spruce
Douglas fir
(Pseudotsuga taxifolia)
Port Orford white cedar
(Chamaecyparis
lawsoniana)
May be used as substitute for spruce in same sizes or in
slightly reduced sizes if reductions are substantiated
Douglas fir
(Pseudotsuga taxifolia)
its strength property Slightly exceeds spruce
except 8% deficient in
shear
Noble fir
(Abies procera, also
known as Abies nobilis)
Satisfactory characteristics of workability, warping,
and splitting. May be used as direct substitute for spruce in
same sizes if shear does not become critical.
Noble fir
(Abies procera, also
known as Abies nobilis)
its strength property Slightly exceeds spruce
Western hemlock
(Tsuga heterophylla)
Less uniform in texture than spruce. May be used as direct
substitute for spruce. Upland growth superior to lowland
growth. Satisfactory for gluing.
Western hemlock
(Tsuga heterophylla)
its strength property Properties between
85% and 96% those
of spruce
Northern white pine, also
known as Eastern white
pine (Pinus strobus)
Excellent working qualities and uniform in properties, but
somewhat low in hardness and shock-resistance.
Cannot be used as substitute for spruce without increase in
sizes to compensate for lesser strength.
Northern white pine, also
known as Eastern white
pine (Pinus strobus)
May be used as substitute for spruce in same sizes or in
slightly reduced sizes if reductions are substantiated.
Easy to work with hand tools.
Port Orford white cedar
(Chamaecyparis
lawsoniana)
its strength property is Slightly less than spruce
except in compression
(crushing) and shear
Yellow poplar
(Liriodendron
tulipifera)
Excellent working qualities. Should not be used as a direct
substitute for spruce without carefully accounting for slightly
reduced strength properties. Somewhat low in shock-resistance.
Satisfactory for gluing.
Yellow poplar
(Liriodendron
tulipifera)
To help determine the suitability of the wood, _________ that would make it unsuitable material to repair
or construct an aircraft.
inspect it
for defects
The ____________ grade the wood for possible use.
type, location, and amount
or size of the defects
All
woods used for structural repair of aircraft are classified as
softwood
is typically used for construction and is
graded based on strength, load carrying ability, and safety.
Softwood
on the other hand, are typically appearance
woods and are graded based on the number and size of clear
cuttings from the tree.
Hardwoods,
defects are permitted in the wood species used
for aircraft repair
1.Cross grain
2.Wavy, curly, and interlocked grain
3. Hard knots
4. Pin knot clusters
5. Pitch pocket
6. Mineral streaks
— is acceptable if the grain
does not diverge from the longitudinal axis of the
material more than specified in Figure 6-10 column
Spiral grain, diagonal grain, or a
combination of the two
A check of all four faces of the board is necessary
to determine the1._______. The direction
of ____________ frequently assists in determining
grain direction.
- amount of divergence
2.free-flowing ink
Acceptable, if
local irregularities do not exceed limitations specified
for spiral and diagonal grain.
Wavy, curly, and interlocked grain
Sound, hard knots up to______ in
diameter are acceptable
3/8 inch
Sound, hard knots up to 3
⁄8-inch in
diameter are acceptable if: (1) they are not projecting
portions of 1._______, along the edges of rectangular or
beveled unrouted beams, or along the edges of flanges
of box beams (except in portions of low stress); (2)
they do not cause 2._______ at the edges of the
board or in the flanges of a beam more than specified
in Figure 6-10 column 3; and (3) they are in the 3.______of the beam and not closer than 4._________ to
another knot or other defect (pertains to 3
⁄8-inch knots;
smaller knots may be proportionately closer). Knots
greater than 5.___________ must be used with caution.
1.I-beams
2. grain divergence
3. center, third
4.20-inches
5. ¼-inch
—small clusters are acceptable if they
produce only a small effect on grain direction.
Pin knot clusters
—Acceptable in center portion of a beam
if they are at least 14-inches apart when they lie in
the same growth ring and do not exceed 1½-inches in
length by 1
⁄8-inch width by 1
⁄8-inch depth, and if they
are not along the projecting portions of I-beams, along
the edges of rectangular or beveled unrouted beams,
or along the edges of the flanges of box beams.
Pitch pockets
Pitch pockets—Acceptable in center portion of a beam
if they are at least 1._________ apart when they lie in
the same growth ring and do not exceed 2.________ in
length by 3.__________, and if they
are not along the projecting portions of 4.______, along
the edges of rectangular or beveled unrouted beams,
or along the edges of the flanges of box beams.
1.14-inches
2.1½-inches
3. 1
⁄8-inch width by 1
⁄8-inch depth
4.I-beams
—acceptable if careful inspection fails
to reveal any decay.
Mineral streaks
The following defects are not permitted in wood used for
aircraft repair. If a defect is listed as unacceptable, please refer
to the previous section, Defects Permitted, for acceptable
conditions.
- Cross grain
- Wavy, curly, and interlocked grain
- Hard knots
- Pin knot clusters
- Spike knots
- Pitch pockets
- Mineral streaks
- Checks, shakes, and splits
- Compression
- Compression failures
- Tension
- Decay
—unacceptable, if they produce large
effect on grain direction.
Pin knot clusters
—knots running completely through the
depth of a beam perpendicular to the annual rings
and appear most frequently in quarter-sawed lumber.
Reject wood containing this defect.
Spike knots
—unacceptable, if accompanied by
decay.
Mineral streaks
are longitudinal
cracks extending, in general, across the annual rings
checks
are longitudinal cracks usually between two
annual rings.
Shakes
are longitudinal cracks caused
by artificially induced stress
Splits
—very detrimental to strength and is
difficult to recognize readily, compression wood
is characterized by high specific gravity, has the
appearance of an excessive growth of summer wood,
and in most species shows little contrast in color
between spring wood and summer wood.
Compression
compression wood
is characterized by
high specific gravity
—caused from overstress in
compression due to natural forces during the growth
of the tree, felling trees on rough or irregular ground,
or rough handling of logs or lumber.
Compression failures
are characterized by a buckling of the fibers
that appears as streaks substantially at right angles to
the grain on the surface of the piece, and vary from
pronounced failures to very fine hairlines that require
close inspection to detect
Compression
failures
—forming on the upper side of branches and
leaning trunks of softwood trees,
Tension
is
caused by the natural overstressing of trying to pull
the branches and leaning trunk upright
tension wood
—rot, dote, red heart, purple heart, etc., must
not appear on any piece
Decay
play a critical role in the bonding of
aircraft structure
adhesives
the mechanic must employ only those types
of adhesives that meet ________–
necessary for use in certificated aircraft.
all of the performance requirements
The product must
be used strictly in accordance with the __________-
aircraft and adhesive
manufacturer’s instructions
All instructions must be
followed exactly, including
the mixing ratios
, the ambient and surface temperatures
, the open and closed assembly times,
the gap-filling ability, or glue line thickness,
the spread of the adhesive,
whether one or two surfaces,
and the amount of clamping pressure and time required for full cure of the adhesive.
provides information on the criteria for
identifying adhesives that are acceptable to the FAA.
AC 43.13-1
AC 43.13-1 provides information on the criteria for
identifying adhesives that are acceptable to the FAA. It
stipulates the following:
- Refer to the aircraft maintenance or repair manual for
specific instructions on acceptable adhesive selection
for use on that type aircraft. - Adhesives meeting the requirements of a MILSPEC, Aerospace Material Specification (AMS), or
Technical Standard Order (TSO)
(AMS) meaning
Aerospace Material Specification
(TSO) meaning
Technical Standard Order
Some of the more common
adhesives that have been used in aircraft construction and
repair include
casein glue, plastic resin glue, resorcinol glue,
and epoxy adhesives.
should be considered obsolete for all aircraft
repairs.
Casein glue
The adhesive deteriorates when __________ that are part of the normal
operating environment of any aircraft.
exposed to moisture
and temperature variations
: Some modern adhesives are incompatible with
casein
adhesive
. If a joint that has previously been bonded with
casein is to be reglued using another type adhesive, all traces
of the casein must be 1._____ before a new adhesive is
applied. If any casein adhesive is left,2.___________ may
cause the new adhesive to fail to cure properly.
1.scraped off
2. residual alkalinity
came on the market in the middle to late 1930s.
Plastic resin glue, also known as a urea-formaldehyde
adhesive,
, is a
two-component synthetic adhesive consisting of resin
and a catalyst.
Resorcinol glue, or resorcinol-formaldehyde glue
. It has better wet-weather and ultraviolet
(UV) resistance than other adhesives. This glue meets all
strength and durability requirements if the fit of the joint and
proper clamping pressure results in a very thin and uniform
bond line.
Resorcinol glue, or resorcinol-formaldehyde glue
The ________- must be followed
regarding mixing, usable temperature range, and the open
and close assembly times.
manufacturer’s product data sheets
The manufacturer’s product data sheets must be followed regarding
mixing, usable temperature range, and the open
and close assembly times.
Resorcinol glue-It is very important that this type
of glue is used at the 1.________ temperatures because
the full strength of the joint cannot be relied on if assembly
and curing temperatures are 2,_______-.
1.recommended
2.below 70 °F
is a two-part synthetic resin product
that depends less on joint quality and clamping pressure.
Epoxy adhesive
Definition of Terms Used in the Glue Process
- Close contact adhesive
- Gap-filling adhesive
- Glue line
- Single spread
- Double spread
- Open assembly time
- Closed assembly time
- Pressing or clamping time
- Caul
- Adhesive pot life
—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.
Close contact adhesive
to allow a glue line of no more than_______-
inch gap.
0.005
—an adhesive suitable for use
in those joints in which the surfaces to be joined
may not be close or in continuous contact
Gap-filling adhesive
—resultant layer of adhesive joining any two
adjacent wood layers in the assembly.
Glue line
—spread of adhesive to one surface only.
Single spread
—spread of adhesive to both surfaces
and equally divided between the two surfaces to
be joined.
Double spread
—period of time between the
application of the adhesive and the assembly of the
joint components.
Open assembly time
—time elapsing between the
assembly of the joints and the application of pressure.
Closed assembly time
—time during which
the components are pressed tightly together under
recommended pressure until the adhesive cures
Pressing or clamping time
Pressing or clamping time—time during which
the components are pressed tightly together under
recommended pressure until the adhesive cures (may
vary from __________ pounds per square inch (psi) for
softwoods, depending on the viscosity of the glue).
10 to 150
—a clamping device, usually two rigid wooden
bars, to keep an assembly of flat panel boards aligned
during glue-up.
Caul
—time elapsed from the mixing
of the adhesive components until the mixture must
be discarded, because it no longer performs to its
specifications.
Adhesive pot life
is a product of time
and temperature.
Pot life
should develop the
full strength of the wood under all conditions of stress.
Satisfactory glue joints in aircraft
To produce this result, the conditions involved in the
gluing operation must be carefully controlled to obtain a _______ in the joint
with adequate adhesion to both surfaces of the wood.
continuous, thin, uniform film of solid glue
To produce this result, the conditions involved in the
gluing operation must be carefully controlled to obtain a continuous, thin, uniform film of solid glue in the joint
with adequate adhesion to both surfaces of the wood.These
conditions required:
- Proper and equal moisture content of wood to be joined
(8 to 12 percent). - Properly prepared wood surfaces that are machined
or planed, and not sanded or sawed. - Selection of the proper adhesive for the intended task,
which is properly prepared and of good quality. - The application of good gluing techniques, including
fitment, recommended assembly times, and adequate
equal pressure applied to the joint. - Performing the gluing operation under the
recommended temperature conditions.
what is the percent of Proper and equal moisture content of wood to be joined
(8 to 12 percent)
The surfaces to be joined must be .
clean, dry, and free from
grease, oil, wax, paint, etc
Keep large prepared surfaces
covered with a _________ prior to the
bonding operation.
plastic sheet or masking paper
are the best
surfaces for gluing solid wood.
Smooth even surfaces produced on planers and joiners
with sharp knives and correct feed adjustments
The use of _______
for gluing has been discouraged for aircraft component
assembly because of the difficulty in producing a surface
free of crushed fibers
sawn surfaces
A light sanding of the surface with
_________ in the direction of the grain restores the
surface fibers to their original condition, removes the gloss,
and improves the adhesion of the glue.
220-grit sandpaper
are a useful means of detecting the presence of
wax
Wetting tests
The__________– should be followed for the
preparation of any glue or adhesive.
manufacturer’s directions
The recommended
proportions of glue, catalyst, and water or other solvent should
be determined by the______.
weight of each component
To make a satisfactorily bonded joint, it is generally desirable
to apply adhesive to _____.
both surfaces and join in a thin even layer
The adhesive can be applied with a 1.____________. Follow the 2._______ for satisfactory results.
- brush, glue spreader, or
a grooved rubber roller - adhesive manufacturer’s
application instructions
