MIL-DTL-55353A
4.5.2 Acoustic quality (see 3.3.1). A voltage of 1.1 volts ±0.1 volt rms shall be applied continuously to the
terminals of the earphone. The frequency shall be varied continuously from 100 Hz to 7,000 Hz and back to 100
Hz. The acoustic output shall be checked for buzzing, rattling, and other spurious sounds.
TABLE IV. Classification of defects for visual and mechanical inspection.
Defect type
Classification
Major
Minor
Dimensions
Dimensions not as specified.
Materials and finish
Materials not as specified.
Scratches, cuts, abrasions, etc., causing
Wrong or incomplete finish.
exposure of base metal, or relatively
Large amount of flaking, peeling, or
small amounts of flaking, peeling, or
chipping of finish.
chipping.
Defective parts which would reduce
Parts
Missing parts.
efficiency of use, but not cause failure
Inoperative, improperly assembled, or
in service.
defective parts which could cause the
Cracks or chipped surfaces having no
headset to fail in service.
effect on the functioning, assembly,
Wrong parts.
maintenance, or life of the headset.
Marking
Marking missing, illegible, or incorrect.
Marking dirty or smudged, but legible.
Any metallic or nonmetallic foreign object
Foreign objects
Any metallic foreign object, not firmly
which affects appearance but which
attached 1/, which could cause
would not cause acoustical
acoustical malfunctioning of the
malfunctioning of the headset.
headset or a short circuit.
Any nonmetallic foreign object such as
insulation, dirt, or phenolic chips which
could cause acoustical malfunctioning
of the headset.
Wiring
Wiring not in accordance with 3.2.1.
Broken strands: 20 percent or less. In a
Broken strands: More than 20 percent;
seven-strand conductor, one or two
except in a seven-strand conductor,
broken strands.
more than two broken strands.
Insulation burned, abraded, pinches or
Insulation burned, abraded, pinched, or
deteriorated, with exposure of bare
deteriorated between two or more
wire, but short circuit not possible.
conductors, resulting in a potential
Taut wire: Slight stress on conductor,
short circuit.
but no possibility of subsequent
Taut wire: Wire exhibits no slack and
breakage.
subsequent breakage may occur due
to stress on terminal or part.
Insulation frayed to the extent that a
potential short circuit exists.
1/
Foreign objects that cannot be dislodged by the moderate application of pressure with a pick shall be
considered to be firmly attached.
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