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

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

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

Laminated wood spars may be substituted for solid rectangular wood spars ________.

if the same quality of wood is used in both

Pin knot clusters are permitted in wood aircraft structure provided ________.

they produce a small effect on grin direction

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

AC 43.13-1B

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.

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

Careful inspection fails to reveal decay.

Which statement about wood decay is correct? A. Decay that occurs before the wood is seasoned does not affect the strength of the finished part. 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.

Decay is not acceptable in any form or amount.

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

compression

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

compression failure

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

glue

The 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 ________.

parallel grain construction

The I-beam wooden spar is routed to ________.

reduce weight

Glue deterioration in wood aircraft structure is indicated ________.

when a joint has separated and the glue surface shows the imprint of the wood with no wood fibers clinging to the glue