MIL-PRF-38039D
3.4.1.3.2 Reduced voltage. Reduced voltage, when the primary panel lighting is ON,
shall be in accordance with MIL-STD-411 and this specification.
3.4.1.4 Mounting and interchangeability. Legend lights shall be mounted flush with the
top surface of the panel whenever possible. To avoid possible obscuration by displays, the legend
light may be raised to the level of the adjacent displays. If individual display indicators are used
for the output of each of the readout circuits, they shall be interchangeable and the mounting
shall be such that the displays may be changed from outside the assembly.
3.4.2 Master warning, master fire warning, and master caution light reset. Master
warning, master fire warning, and master caution indicators shall incorporate push-to-reset light
devices for extinguishing the light precautions. The load required to extinguish the push-to-reset
light device shall be 2 ± 0.5 pounds.
3.4.3 Circuits. Only solid state circuits shall be used.
3.4.3.2 Label. The indicator display system, as exposed to the pilot, shall contain a
PRESS TO TEST label and a WARNING, CAUTION, and ADVISORY SYSTEM label. The
labels shall be prepared in accordance with an industrially accepted method (see 6.3.4).
3.4.3.3 Controls. The controls for the indicator system may be either one or two
sections. If in one section, the indicator displays shall be mounted on the visible portion of the
case. The number of sections and size of the case shall be subject to approval of the procuring
activity (see 6.2).
3.4.3.3.1 Sealing. The case shall be filled and hermetically sealed. The label indicating
the function of the panel (WARNING, CAUTION, or ADVISORY SYSTEM) shall not be
within the hermetically sealed case. The case shall allow internal mechanisms to be removed,
replaced, and the case refilled and resealed without the use of special tools or fixtures unless they
are approved by the procuring activity (see 6.2).
3.4.3.3.2 Filling medium. The filling medium shall be of at least 98% purity, free of dust
particles, and shall contain not more than 0.006 milligram of water vapor per liter (dewpoint -
65°C at the filling pressure). The filling medium shall be 88% to 92% nitrogen and the remainder
helium. The absolute pressure of the filling medium in the case shall be approximately 1
atmosphere.
3.4.4 Wiring. Internal wiring shall be color coded according to an industrially accepted
method (see 6.3.1).
3.4.5 Test provisions. Provisions, such as test points, shall be made for testing all
subsystem circuitry and indicator lamp circuitry.
3.4.5.1 Press-to-control. All master warning, master fire warning, master caution, and
advisory lights shall be activated when the press-to-test control is depressed. The indicator
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