Baker's O&P Airframe study guide
questions
what species of wood is used as a standard for strength properties of other species of wood
used in aircraft structures - ANSspruce is used as the standard of which all woods are
compared
what type of wood quality must be used in the repair of aircraft structures - ANSthe wood must
be of aircraft quality and equivalent to its original strength or greater
what is the difference between laminated wood and plywood - ANSlaminated wood and plywood
consist of two or more layers of wood which have been glued together. laminated wood has the
grain of all layers approx. parallel. the grain of plywood runs 90 degrees with the adjacent ply
what are two types of glue used for aircraft wood structure repair - ANScasin and synthetic resin
glue the resin glues that are recommended for wooden aircraft applications are the resorcinol
formaldehyde type glues
what method is used to prepare plywood for bending - ANSthe wood is soaked in hot water, and
then placed in a form until completely dry
what are the results of using insufficient gluing pressure when making a wood joint - ANSthe
results will normally be thick glue lines, which indicate a weak joint
how long should a wood glue joint be kept under pressure before removing the clamps - ANSthe
pressure time will vary depending on the temperature of the curing room. the curing temps are
from 70 degrees F and up. higher temperatures will cause the glue to set faster. to be certain
that a glue joint is satisfactory, it is recommended that it remain under pressure at about 85
degrees F for a period of at least seven hours. full joint strength will develop only after
conditioning for at least two days
what are some of the various methods used to apply pressure to joints in aircraft gluing
operations - ANSbrads, nails, screws, clamps, or hydraulic and electric power presses
why does the strength of a scarf joint depend upon the accuracy of the two beveled surfaces -
ANSbecause an inaccurate bevel will reduce the amount of effective glue area
what type of patch is preferred for repair of stressed plywood skin and why - ANSa properly
prepared and inserted scarf patch is the best repair for plywood, and is preferred for most skin
, repairs. it deffers from a splayed patch in that the edges are scarfed to a 12 to 1 slope instead of
a 5 to 1 slope, and it uses reinforcements under the patch where the glue joints occur
are mineral streaks acceptable in aircraft wood - ANSyes, providing careful inspection fails to
reveal any decay
how can the moisture content of wood be determined - ANSone way is to use a moisture meter.
however, the most accurate method is to take a sample of the wood, weigh it, dry it in an oven
at a temperature of 100 degrees C to 105 degrees C, reweigh it and then compute the moisture
content by using the following formula
what area of the wood spar may not be spliced - ANSunder the wing attachment fittings, landing
gear fittings, engine mount fittings, or lift-and-interplane strut fittings
what type of joint is generally used is splicing structural members in aircraft - ANSa scarf joint
what is compression wood and why is it not acceptable for aircraft structures - ANScompression
wood is wood that is characterized by high specific gravity and has the appearance of an
excessive growth of summer wood(hard, non-porous). this defect is difficult to recognize and is
very detrimental to strength. reject all material containing compression wood
what are the three forms of wood - ANSsolid, ply, and laminate
what are two forms of wood that are acceptable for the repair of wooden aircraft skin - ANSthe
plywood and laminated woods are preferred for this application
what would be the greatest amount of splices placed into one spar - ANStwo
what determines the required quality and strength of fabric that is to be used for covering aircraft
- ANSdetermined by the pounds per square foot of wing loading(PSF), and the never-exceed
airspeed of the aircraft(VNE)
when are anti-tear strips recommended and where are they used - ANSover the ribs, longerons,
and stringers but are under the reinforcing tape before the fabric is installed. they are
recommended for all areas in the slipstream
what is the maximum permissible deterioration of aircraft fabric before it is considered
unairworthy - ANSfabric covering is considered unairworthy when it deteriorates more than 30
percent from its original required tensile strength
what should be the strength of the fabric used for re-covering an aircraft - ANSall fabric, surface
tape, reinforcing tape, thread and lacing cord used to re-cover or repair an aircraft covering
should be of high grade aircraft textile material. the material must be at least as good a quality
and of equivalent strength as those as those originally used by the aircraft manufacturer
questions
what species of wood is used as a standard for strength properties of other species of wood
used in aircraft structures - ANSspruce is used as the standard of which all woods are
compared
what type of wood quality must be used in the repair of aircraft structures - ANSthe wood must
be of aircraft quality and equivalent to its original strength or greater
what is the difference between laminated wood and plywood - ANSlaminated wood and plywood
consist of two or more layers of wood which have been glued together. laminated wood has the
grain of all layers approx. parallel. the grain of plywood runs 90 degrees with the adjacent ply
what are two types of glue used for aircraft wood structure repair - ANScasin and synthetic resin
glue the resin glues that are recommended for wooden aircraft applications are the resorcinol
formaldehyde type glues
what method is used to prepare plywood for bending - ANSthe wood is soaked in hot water, and
then placed in a form until completely dry
what are the results of using insufficient gluing pressure when making a wood joint - ANSthe
results will normally be thick glue lines, which indicate a weak joint
how long should a wood glue joint be kept under pressure before removing the clamps - ANSthe
pressure time will vary depending on the temperature of the curing room. the curing temps are
from 70 degrees F and up. higher temperatures will cause the glue to set faster. to be certain
that a glue joint is satisfactory, it is recommended that it remain under pressure at about 85
degrees F for a period of at least seven hours. full joint strength will develop only after
conditioning for at least two days
what are some of the various methods used to apply pressure to joints in aircraft gluing
operations - ANSbrads, nails, screws, clamps, or hydraulic and electric power presses
why does the strength of a scarf joint depend upon the accuracy of the two beveled surfaces -
ANSbecause an inaccurate bevel will reduce the amount of effective glue area
what type of patch is preferred for repair of stressed plywood skin and why - ANSa properly
prepared and inserted scarf patch is the best repair for plywood, and is preferred for most skin
, repairs. it deffers from a splayed patch in that the edges are scarfed to a 12 to 1 slope instead of
a 5 to 1 slope, and it uses reinforcements under the patch where the glue joints occur
are mineral streaks acceptable in aircraft wood - ANSyes, providing careful inspection fails to
reveal any decay
how can the moisture content of wood be determined - ANSone way is to use a moisture meter.
however, the most accurate method is to take a sample of the wood, weigh it, dry it in an oven
at a temperature of 100 degrees C to 105 degrees C, reweigh it and then compute the moisture
content by using the following formula
what area of the wood spar may not be spliced - ANSunder the wing attachment fittings, landing
gear fittings, engine mount fittings, or lift-and-interplane strut fittings
what type of joint is generally used is splicing structural members in aircraft - ANSa scarf joint
what is compression wood and why is it not acceptable for aircraft structures - ANScompression
wood is wood that is characterized by high specific gravity and has the appearance of an
excessive growth of summer wood(hard, non-porous). this defect is difficult to recognize and is
very detrimental to strength. reject all material containing compression wood
what are the three forms of wood - ANSsolid, ply, and laminate
what are two forms of wood that are acceptable for the repair of wooden aircraft skin - ANSthe
plywood and laminated woods are preferred for this application
what would be the greatest amount of splices placed into one spar - ANStwo
what determines the required quality and strength of fabric that is to be used for covering aircraft
- ANSdetermined by the pounds per square foot of wing loading(PSF), and the never-exceed
airspeed of the aircraft(VNE)
when are anti-tear strips recommended and where are they used - ANSover the ribs, longerons,
and stringers but are under the reinforcing tape before the fabric is installed. they are
recommended for all areas in the slipstream
what is the maximum permissible deterioration of aircraft fabric before it is considered
unairworthy - ANSfabric covering is considered unairworthy when it deteriorates more than 30
percent from its original required tensile strength
what should be the strength of the fabric used for re-covering an aircraft - ANSall fabric, surface
tape, reinforcing tape, thread and lacing cord used to re-cover or repair an aircraft covering
should be of high grade aircraft textile material. the material must be at least as good a quality
and of equivalent strength as those as those originally used by the aircraft manufacturer
