MIL-DTL-24784 / 21B (SH)
descriptive signal names. The signal name shall be identical on all FCD sheets. No
signal name shall be used for more than one signal path.
2.
Reference designations shall not be used as signal names except in cases where no other
name exists (primarily on power FCDs).
3.
The FBD or FCD number, sheet, and zone shall be used to identify signal origins and
destinations when referencing from one FCD to another or from an FCD to an FBD.
b.
Signal referencing for FCDs shall be in accordance with 3.5.1.1.2.
c.
General format items. The following shall, at a minimum, be located on the FCD first sheet:
1.
Notes that apply specifically to that FCD.
2.
Special abbreviations (that is, P/O).
3.
A note to explain the position (energized/de-energized, on/off) of any relays or switches
shown on the FCD.
4.
All assemblies shall reference an internal schematic when necessary for troubleshooting
and maintenance.
5.
Power and logic FCDs shall carry specific signal names on the flow lines. If signal names
are not readily available, then the signal name may indicate a hardware destination point
(that is, K3-82).
d.
Diagram type, equipment names, and function names shall be in accordance with 3.5.1.1.2.
e.
Key codes. In certain applications, both digital and analog modules shall be assigned key
codes. Most key codes consist of three letters (KDM, KDN, and so forth). The logic or
analog symbol on the FCD shall contain the key code for the circuit module (or portion of the
circuit module) depicted. These key codes permit the users to locate a text description of
circuit operations located in the technical manual.
f.
Diagram (drawing) numbers, sheet numbers, and zone numbers shall be in accordance with
3.5.1.1.2.
g.
Reference designations shall be in accordance with 3.6.6.4.
h.
Test points. All monitored and nonmonitored test points shall be incorporated in all FCDs.
These test points shall be shown as part of the circuitry they are testing and shall indicate the
following information and parameters:
1.
Test point number.
2.
Test point operational connector pin (if applicable).
3.
Circuitry associated with test point (for example, divider network).
4.
Test point symbology per IEEE 315.
3.5.1.3.2 Diagram drafting requirements. This subsection defines the requirements for line
weights, methods of depicting interconnecting lines, symbol sizes, lettering size, and notes in the
preparation of FCDs (see 3.5.1.1.3 and the following).
a. FCD logic symbols shall be drawn as medium (0.01 inch) lines. Other symbols depicting
assemblies shall be drawn rectangular and to the minimum size which will allow inputs and
outputs to be depicted and include all reference data within the symbol. All like symbols shall
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