lines. Narrow or tight cracks show up as a series of red dots close
Scattered dots that do not show a pattern indicate
Because this method is so sensitive, evaluating the
indicated cracks requires good judgment.
After the flaws have been
detected and marked, remove the developer with dye remover or an
approved petroleum solvent.
Dye-penetrant materials are flammable, particularly the
developer. They must be used only in well-ventilated areas away from
sparks or flames.
The fumes must not be breathed for prolonged
periods; and gloves, goggles, and aprons are recommended for
Contaminated skin must be washed with soap and water,
and contaminated clothing must be changed at once and laundered
When the existence and extent of the damage has been evaluated, it
must be classified. The classifications for damage are--
Repairable by patching.
Repairable by insertion.
In many instances the availability, or scarcity, of repair materials
and time determines whether or not a damaged part is repaired or
Damage that does not impair the structural
soundness of the member involved or that can be repaired without
putting flight restrictions on the aircraft is negligible damage.
Examples of negligible damage include small dents, scratches, cracks,
or holes that can be repaired by smoothing, sanding, stop drilling,
hammering, or other methods without additional materials.
Damage that exceeds limits set for
negligible damage and can be repaired by bridging it with splice
material is damage repairable by patching. Splice or patch material
used to make internal or riveted and bolted repairs is usually the
same kind of material as the original only one gage heavier.
patch repairs, filler plates identical to the gage and material of
the damaged component can be used to return the damaged part to its