AIRFRAME O&P EXAM QUESTIONS
AND ANSWERS GRADED A+ 2025/2026
What species of wood is used as a standard for strength properties of other species of wood
used in aircraft structures? - ANS Sitka Spruce
What is the difference between laminated wood and plywood? - ANS Laminated has a
parallel (consistent) wood grain throughout the layers, plywood is mixed.
What are the two types of glue used for aircraft wood structure repair? - ANS Epoxy glue and
Plastic resin glue.
What method is used to prepare plywood for bending? - ANS Soaked in hot water then
placed on a form till dry.
What are the results of using insufficient gluing pressure when making a wood joint? -
ANS Thick glue lines indicating weak joints.
What are some of the various methods used to apply pressure to joints in aircraft gluing
operations? - ANS Brads, Nails, Screws, Clamps, and presses (hydraulic and electric).
Why does the strength of a scarf joint depend upon the accuracy of the two beveled surfaces? -
ANS An inaccurate bevel will reduce the effective glue area.
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
,What area of a wood spar may not be spliced? - ANS Under wing attachments, landing gear,
engine mount, and interplane strut fittings.
What type of joint is generally used in splicing structural members in aircraft? - ANS A scarf
Joint.
Are mineral streaks acceptable in aircraft wood? - ANS Yes, if careful inspection fails to reveal
any decay.
What is compression wood and why is it not acceptable for aircraft structures? - ANS Wood
that has high specific gravity and appearance or high summer growth. It's very detrimental to
strength.
What determines the required quality and strength of fabric that is to be used for covering
aircraft? - ANS PSF of wing loading and the 'never-exceed' airspeed.
What is the maximum permissible deterioration of aircraft fabric before it is considered
unworthy? - ANS More than 30% from its original tensile strength.
What is the purpose, location, and method of installing drain grommets in aircraft fabric? -
ANS Purpose is to allow moisture to leave the aircraft and furnish ventilation. Located under
the airfoil at the trailing edge, close to the rib, and at the lowest point on the center of the
fuselage bay. Brass grommets should be mounted on fabric patches and then doped; plastic
grommets are doped directly to the covering.
What is the purpose of reinforcing tape? - ANS To prevent the stitching cord from cutting
through the fabric.
What methods are used to check the strength of doped fabric? - ANS Puncher testers or a lab
test to determine the actual strength of the fabric.
What should be done with structure that will come in contact with doped fabric? - ANS Treat
parts that will come in contact with a protective coating such as dope-proof paint.
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
, If the original rib stitch spacing cannot be determined when re-covering an aircraft, what rib
stitch spacing should be used? - ANS Refer to the spacing chart in AC 43.13-1B.
What is the standard tie-off knot used during rib stitching? - ANS Modified Seine knot.
Name two organic and two synthetic fibers used for covering aircraft. - ANS Organic: Cotton
and linen. Synthetic: Fiberglass and heat shrinkable fiber like nylon, and orlon.
What causes blushing when applying dope or lacquer, and how can it be prevented? -
ANS Caused by humidity, prevented by paint retarder or heating the room.
What are 2 types of dope used for aircraft finishes? - ANS Nitrate and butyrate.
What is applied to metallic surfaces as a corrosion resistant covering before the application of
enamel or lacquer? - ANS Zinc chromate primer.
What are the most common methods of applying aircraft finishes? - ANS Dipping, brushing,
and spraying.
What type of paint may be used over any paint system that is in good condition? - ANS Epoxy
topcoats.
What is normally the cause of runs and sags in a spray paint finish? - ANS Holding the gun too
long in one place which applies too much paint.
What is used to thin zinc chromate primers? - ANS Toluene.
What type of materials should be thoroughly protected when using paint remover? -
ANS Synthetic rubber surfaces, aircraft tires, fabric, and acrylic.
3 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
AND ANSWERS GRADED A+ 2025/2026
What species of wood is used as a standard for strength properties of other species of wood
used in aircraft structures? - ANS Sitka Spruce
What is the difference between laminated wood and plywood? - ANS Laminated has a
parallel (consistent) wood grain throughout the layers, plywood is mixed.
What are the two types of glue used for aircraft wood structure repair? - ANS Epoxy glue and
Plastic resin glue.
What method is used to prepare plywood for bending? - ANS Soaked in hot water then
placed on a form till dry.
What are the results of using insufficient gluing pressure when making a wood joint? -
ANS Thick glue lines indicating weak joints.
What are some of the various methods used to apply pressure to joints in aircraft gluing
operations? - ANS Brads, Nails, Screws, Clamps, and presses (hydraulic and electric).
Why does the strength of a scarf joint depend upon the accuracy of the two beveled surfaces? -
ANS An inaccurate bevel will reduce the effective glue area.
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
,What area of a wood spar may not be spliced? - ANS Under wing attachments, landing gear,
engine mount, and interplane strut fittings.
What type of joint is generally used in splicing structural members in aircraft? - ANS A scarf
Joint.
Are mineral streaks acceptable in aircraft wood? - ANS Yes, if careful inspection fails to reveal
any decay.
What is compression wood and why is it not acceptable for aircraft structures? - ANS Wood
that has high specific gravity and appearance or high summer growth. It's very detrimental to
strength.
What determines the required quality and strength of fabric that is to be used for covering
aircraft? - ANS PSF of wing loading and the 'never-exceed' airspeed.
What is the maximum permissible deterioration of aircraft fabric before it is considered
unworthy? - ANS More than 30% from its original tensile strength.
What is the purpose, location, and method of installing drain grommets in aircraft fabric? -
ANS Purpose is to allow moisture to leave the aircraft and furnish ventilation. Located under
the airfoil at the trailing edge, close to the rib, and at the lowest point on the center of the
fuselage bay. Brass grommets should be mounted on fabric patches and then doped; plastic
grommets are doped directly to the covering.
What is the purpose of reinforcing tape? - ANS To prevent the stitching cord from cutting
through the fabric.
What methods are used to check the strength of doped fabric? - ANS Puncher testers or a lab
test to determine the actual strength of the fabric.
What should be done with structure that will come in contact with doped fabric? - ANS Treat
parts that will come in contact with a protective coating such as dope-proof paint.
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
, If the original rib stitch spacing cannot be determined when re-covering an aircraft, what rib
stitch spacing should be used? - ANS Refer to the spacing chart in AC 43.13-1B.
What is the standard tie-off knot used during rib stitching? - ANS Modified Seine knot.
Name two organic and two synthetic fibers used for covering aircraft. - ANS Organic: Cotton
and linen. Synthetic: Fiberglass and heat shrinkable fiber like nylon, and orlon.
What causes blushing when applying dope or lacquer, and how can it be prevented? -
ANS Caused by humidity, prevented by paint retarder or heating the room.
What are 2 types of dope used for aircraft finishes? - ANS Nitrate and butyrate.
What is applied to metallic surfaces as a corrosion resistant covering before the application of
enamel or lacquer? - ANS Zinc chromate primer.
What are the most common methods of applying aircraft finishes? - ANS Dipping, brushing,
and spraying.
What type of paint may be used over any paint system that is in good condition? - ANS Epoxy
topcoats.
What is normally the cause of runs and sags in a spray paint finish? - ANS Holding the gun too
long in one place which applies too much paint.
What is used to thin zinc chromate primers? - ANS Toluene.
What type of materials should be thoroughly protected when using paint remover? -
ANS Synthetic rubber surfaces, aircraft tires, fabric, and acrylic.
3 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
