MIL-DTL-24784 / 21B (SH)
3.6.6.8.2 Fault group index. The fault group index shall provide a list of suspected faulty
assemblies and parts for a fault group number callout resulting from the performance of specific
diagnostic fault detection routines performed at the equipment or system level. Use of this
section shall enable maintainers to swap or replace suspected faulty parts identified by
troubleshooting routines with the use of MAMs, replacements from the supply system, or
redundant parts available within the system. The fault group index is used for repair of a failure.
The fault group index shall consist of a list of callouts or typeouts which list the reference
designator of suspected faulty part(s) causing the callout; and which references the entry point on
the correct diagram for further troubleshooting of casualty. This section shall also contain
references to available lists of swappable components and MAMs, supply data, and instructions
for replacement or swapping of suspected faulty parts. This section shall consist of a tabular
listing of data related to troubleshooting routine callouts. The fault group index may be an
automated printout if format and legibility are retained and reproduced copy is clear and useable.
The fault group index shall contain an introduction describing the use of the table in narrative text.
The fault group index shall contain the following parts:
a. Fault group number. This shall consist of a column of callouts or typeouts listed
alphanumerically by unit number of the diagnostic test performed, and shall contain all callouts
applicable to unit casualties. Entries shall be spaced to facilitate inclusion of all corresponding
data in the other columns of the table.
b. Test. This column shall identify the diagnostic test number of the test that produced the fault
group callout.
c. Unit. This column shall identify the unit that was tested.
d. Card type. This column shall identify the part number of the suspected faulty card.
e. Reference designator. This shall consist of a column of all suspected faulty components
applicable to the corresponding fault group number. Entries shall be spaced one to a line of
type and shall be ranked by highest-to-lowest probability of causing the fault group number
callout, and pluggable components shall be listed preceding hard-wired components. The
reference designator shall describe unit number, cabinet or section number, subassembly
number, and component number.
f. FCD. This column shall identify the figure number of the FCD associated with the suspected
faulty card.
g. Circuit tested. This column shall identify the circuit that was tested.
h. Notes or remarks. This shall consist of notes, remarks, comments or amplifying data related
to repair of the casualty. (Examples of notes and data: Identification of Electrostatic
Discharge (ESD) sensitive parts; reference to applicable Fault Group Replacement
Instructions; and so forth).
3.6.6.8.3 Fault group replacement instruction. This section shall describe by procedural text, the
approved instructions for replacement or swapping of components identified by the fault group
index, including equipment lineups and restrictions and all applicable safety instructions. This
section shall also contain narrative references to other equipment technical manual sections
describing the availability, location, and use of MAMs and redundant swappable components.
3.6.6.9 Troubleshooting diagrams. Troubleshooting diagrams shall consist of Fault Logic
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