MIL-DTL-24784/20B (SH)
operating all system diagnostic operating procedures.
3.6.6.6 System troubleshooting procedures. This section shall provide specific troubleshooting
methods and procedures to direct fault identification and location, fault-isolation, and fault repair
or correction at the system level. The procedures shall provide for the analysis of switching
combinations and observable indications (dials, gauge lamps, and meters). The use of any
required test equipment shall be described. The procedures shall support the fault logic diagrams
(FLDs), FCDs, and sequenced switching diagrams (SSDs). The supporting diagrams shall be
referenced by figure number. Prerequisite control settings, conditions, and tools and test
equipment shall precede each procedure.
3.6.6.6.1 Maintenance concept. The beginning of the system troubleshooting section shall
describe the maintenance concept for system fault detection, fault localization, and fault-isolation
and repair. The section shall contain a flowchart to aid the maintainer by illustrating the
philosophy behind the method used to troubleshoot casualties.
3.6.6.6.2 Maintenance concept flowchart. The flowchart shall illustrate the basic methodology
of troubleshooting casualties. The philosophy or concept behind the troubleshooting method shall
be shown by depicting generalized maintenance actions rather than specific tasks performed.
Overall format of the flowchart shall be divided into Operational, Detection, Localization, and
Isolation and Repair sections by use of labeled dashed lines. Each block of the flowchart shall
contain a circled number that corresponds to a paragraph number of an accompanying narrative
text that describes the content of that block. Block numbers shall be assigned sequentially and
shall follow the top-to-bottom, left-to-right flow pattern used by the flowchart. The flowchart
shall illustrate typical operations performed during the troubleshooting process in the sequence
that they were performed. The flowchart shall represent sufficient examples of the hardware and
software used with the system to illustrate the underlying troubleshooting philosophy. All
inherent or built-in troubleshooting aids shall be illustrated. However, to minimize complexity,
the flowchart shall not attempt to show all of the possible troubleshooting operations for every
hardware and software combination. (see 3.5.1.2).
3.6.6.6.3 Maintenance concept flowchart definitions. This section shall describe each of the
blocks of the maintenance concept flowchart and their content by use of narrative text presented
in tabular form. The table shall consist of paragraphs referenced to the numbered block of the
flowchart that is described. The table shall contain a separate sequentially numbered description
for each block appearing on the maintenance concept flowchart.
3.6.6.6.4 FLDs. The FLDs shall be prepared in accordance with MIL-DTL-24784.
3.6.6.6.5 SSDs. SSDs may be used to step the technician through a sequence of events to
support troubleshooting. SSDs are generally used when normal monitoring of events will miss
symptoms that are significant to the troubleshooting process. This can be due to the speed that
the events take place, the need for controlling operator actions or other circumstances that make a
step-by-step monitoring of events useful to the troubleshooting process. SSDs are often used to
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