Airframe (AMA) Chapters- Wood Structures

In cases of elongated bolt holes in a wood spar or cracks in the vicinity of boltholes, a) it is permissible to ream the hole, plug with hardwood, and redrill b) the spar may be reinforced by using hardwood reinforcing plates c) a new section of spar should be spliced in or the spar replaced entirely

a new section of spar should be spliced in or the spar replaced entirely exp. the only repair that is approved for an elongated bolt hole in a wood aircraft wing spar is to cut out the section of the spar that contains the damage and splice in a new section

Which statement concerning wood decay is correct? a) Decay that appears to be mineral streaks is acceptable b) A limited amount of decay along the beveled edges of unrouted beams is acceptable c) Any form or amount of decay is not permitted

any form or amount of decay is not permitted Exp. 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

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) parallel to the grain c) at right angles to the grain

at right angles to the grain Exp. Compression Failure in aircraft structural wood is characterized by a streak on the surface of the wood at right angles to the grain.

The I-beam wooden spar is routed to a) increase strength b) obtain uniform strength c) reduce weight

reduce weight Exp. 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 the this material.

Pin Knot clusters are permitted in wood aircraft structure provided a) they produce a small effect on grain direction b) they have no mineral streaks c) no pitch pockets are within 12 inches

they produce a small effect on grain direction Exp. 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

A faint line running across the grain of a wood spar generally indicates a) compression failure b) shear failure c) decay

Compression Failure Exp. A compression failure in a piece of wood is identified by a faint line running across the grain of the wood.

Where is information found concerning acceptable species substitutions for wood materials used in aircraft repair a) AC 43.13-1B b) Aircraft Specifications or Type Certificate Data Sheets c)Technical Standard Orders

AC 43.13-1B Exp. The list of acceptable species of wood materials used in aircraft structure is found in Table 1-1 AC 43.13-1B

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

Careful inspection fails to reveal any decay Exp. 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

Which statement about wood decay is correct a) Decay that occurs before the wood is seasoned does not affect the strength of the finished place 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

Decay is not acceptable in any form or amount Exp. 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

When patching a plywood skin, abrupt changes in cross-sectional areas which will develop dangerous stress concentration should be avoided by a) circular or elliptical patches b) square patches c) doublers with any desired shaped patches

circular or elliptical patches Exp. Circular or elliptical patches are used when patching aircraft plywood skin to prevent abrupt changes in the cross-sectional area of skin. If a rectangular or triangular patch is used, the corners must have ample radii.

any wooden member that has been overstressed is subject to which type of failure a) stretch b) compression c) torsion

compression Exp. Compression failure of a wood structure can take place when that wood structure is overstressed

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

glue Exp. 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.

Laminated wood spars may be substituted for solid rectangular wood spars a) only in certain instances where the primary load is shared by one or more other original structural member b) if the same quality wood is used in both c) only upon specific approval by the manufacturer or the FAA

if the same quality wood is used in both Exp. Laminated wood spars may be substituted for solid rectangular wood spars if the same quality of wood is used in both

The cantilever wing uses a) external struts or wire bracing b) no external bracing c) the skin to carry most of the load the wing butt

no external bracing Exp. A cantilever wing has all its strength inside its structure. The wing spars are built in such a way they carry all the bending and torsional loads. A cantilever wing uses no external bracing.

Laminated wood is sometimes used in the construction of highly stressed aircraft components. This wood can be identified by its a) parallel grain construction b) similarity to standard plywood c) perpendicular grain construction

parallel grain construction Exp. 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.

Glue deterioration in wood aircraft structure is indicated a) when a joint has separated and the glue surface shows only the imprint of the wood with no wood fibers clinging to the glue b) when a joint has separated and the glue surface shows pieces of wood and/or wood fibers clinging to the glue c) by any joint separation

when a joint has separated and the glue surface shows only the imprint of the wood with no wood fibers clinging to the glue Exp. A satisfactory glue joint has the strength of the wood. When a glue join fails, the wood fibers should separate before the glue fails. if the joint separates with no wood fibers clinging to the glue, the glue has deteriorated.