What is the acceptable moisture content for aircraft timber?

It must generally be maintained between 10% and 15%.

Are any defects permitted in aircraft grade timber?

Only minor defects like small pin knots and slight surface checks may be permitted under strict tolerances, whereas decay, brashness, and severe cross-grain are strictly prohibited.

Which IS code details the testing methods for this timber?

IS 1708 covers the methods of testing small clear specimens of timber.

IS 1898

: 1990

Timber for aircraft construction in converted form (finished form)

CurrentSpecializedSpecificationMaterials Science · Timber and Timber Stores

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This standard lays down the requirements, grading, and permissible defects for timber in converted (finished) form specifically intended for use in aircraft and glider construction.

Timber for aircraft construction in converted form (finished form)

Quick Reference Values

Moisture Content10% to 15% (typically standardized at 12%)

Maximum Permissible Slope of Grain1 in 15

Standard Test Temperature27 ± 2 °C

Practical Notes

Aircraft timber requires stringent visual and mechanical inspection; prohibited defects like brashness, decay, and large knots must be completely avoided.

Slope of grain profoundly affects the tensile and bending strength of the timber and must be accurately verified.

Moisture content should be strictly maintained to ensure dimensional stability and consistent strength properties during flight.