Prepware Airframe_Wood Structures

In cases of elongated bolt holes in a wood spar or cracks in the vicinity of bolt holes,

A new section of spar should be spliced in or the spar replaced entirely. EXPL: The only repair that is approved for an elongated bolt hole in a wood aircraft wing apar is to cut out the section of the spar that contains the damage and splice in a new section. REF: AC 43.13-1B

Compression failures in wood aircraft structures are characterized by buckling of the fibers that appear as streaks on the surface

At right angles to the grain. EXPL: Compression failure in aircraft structural wood is characterized by a streak on the surface of the wood at right angles to the grain. REF: REF: AC 43.13-1B

The cantilever wing uses

No external bracing. EXPL: A cantilever wing has all its strength inside its structure. The wing spars are built in such a way that they carry all the bending and torsional loads. A cantilever wing uses no external bracing. REF: AMT-STRUC

Pin knot clusters are permitted in wood aircraft structure provided

They produce a small effect on grain direction. EXPL: Pin knot clusters in a piece of aircraft structural wood are permitted if they are small clusters and produce only a small effect on grain direction. REF: AC 43.13-1B

Glue deterioration in wood aircraft structure is indicated

When a joint has separated and the glue surface shows only the imprint of the wood with no wood fibers clinging to the glue. EXPL: A satisfactory glue joint has the strength of the wood. When a glue joint fails, the wood gibers should separate before the glue fails. If the joint separates with no wood fibers clinging to the glue, the glue has deteriorated. REF: AMT-STRUC Chapter 3

A faint line running across the grain of a wood spar generally indicates

Compression failure. EXPL: A compression failure in a piece of wood is identified by a faint line running across the grain of the wood. REF: AC 43.13-1B

Any wooden member that has been overstressed is subject to which type of failure?

Compression. EXPL: Compression failure of a wood structure can take place when that wood structure is overstressed. REF: AC 43.13-1

Where is information found concerning acceptable species substitutions for wood materials used in aircraft repair?

AC 43.13-1B EXPL: The list of acceptable species of wood materials used in aircraft structure is found in Table 1-1 of AC 43.13-1B REF: AC 43.13-1B

Which statement concerning wood decay is correct?

Any form or amount of decay is not permitted. EXPL: When inspecting a wooden aircraft structure, examine all stains and discolorations carefully to determine whether or not they are harmless or in a stage of preliminary or advanced decay. All pieces must be free from rot, dote, red heart, purple heart, and all other forms of decay. REF: AC 43.13-1

Which of the following will determine acceptance of wood with mineral streaks?

Careful inspection fails to reveal any decay, EXPL: Wood having mineral streaks is acceptable for aircraft structure, provided careful inspection does not reveal any decay. Mineral streaks have no effect on the direction of the grain in the wood. REF: AC 43.13-1B

When patching a plywood skin, abrupt changes in cross-sectional areas which will develop dangerous stress concentration should be avoided by using

Circular or elliptical patches. EXPL: Circular or elliptical patches are used when patching aircraft plywood skin to prevent abrupt changes in cross-sectional area of the skin. If a rectangular or triangular patch is used, the corners must have ample radii. REF: AMT-STRUC Chapter 3

Which statement about wood decay is correct?

Decay is not acceptable in any form or amount. EXPL: When inspecting a wooden aircraft structure, examine all stains and discolorations carefully to determine whether or not they are harmless or in a stage of preliminary or advanced decay. All pieces must be free from rot, dote, red heart, purple heart, and all other forms of decay. REF: AC 43.13-1B

The Strength of a well-designed and properly prepared wood splice joint is provided by the

Glue EXPL: The strength of a well-designed and properly prepared wood splice is provided completely by the glue. No other type of load-carrying fastener is used in a glued joint. REF: AC 43.13-1B

Laminated wood spars may be substituted for solid rectangular wood spars

If the same quality wood is used in both. EXPL: Laminated wood spars may be substituted for solid rectangular wood spars if the same quality of wood is used in both. REF: AMT-STRUC Chapter 3

Laminated wood is sometimes used in the construction of highly stressed aircraft components. This wood can be identified by its

Parallel grain construction. EXPL: Laminated wood is made up of a number of pieces of wood glued together with the grain of all the pieces running in the same direction (parallel to each other). Plywood is also made up of layers of wood, but the grain of each alternate layer runs at an angle to the ones next to it. REF: AMT-STRUC Chapter 3

The I-beam Wooden spar is routed to

Reduce weight. EXPL: A wooden I-beam wing spar is routed to reduce its weight. The material removed is in the web of the spar, and there is very little strength lost by removing this material. REF: AMT-STRUC Chapter 3