The AV-3M system uses codes to process
information. Items of information, such as a
number of hours on aircraft or equipment and
aircraft bureau numbers, are normally expressed
in numerical terms and do not need to be
converted into code. Also, most of the codes used
in the aircraft inventory and reporting system
(AIRS) are used in the AV-3M system without
change. In most other cases, data must be
converted into code to be computer processed.
The basic codes used on the various source
documents are prescribed for Navy-wide use;
therefore, they cannot be changed locally. Some
codes are structured so that flexibility is provided,
allowing expansion to meet local requirements.
Some of the principal codes used by aircraft
maintenance activities are described in the
NOTE: A list of MDS codes is contained in
the appendix section of the latest edition of the
Naval Aviation Maintenance Program,
A structured three-
character alphanumeric code that identifies an
activity within a major command.
Permanent unit code (PUC). A six-character
numeric code assigned to each aircraft reporting
custodian for identification.
Work center code. A three-character alpha-
numeric code used to identify work centers within
Type equipment code (TEC). A four-character
alphanumeric code that identifies the end item of
equipment on which work is performed. There are
16 categories of equipment, identified by the first
character of the TEC. For example, the first code
character for aircraft is A; the first code character
for jet engines is J; and the first code character
for reciprocating engines is R.
Julian date. A four-character numeric code
used to express the date. The first character of
the code is the last digit of the year, and the last
three characters show the day of the year. For
example, 1101 is the 10lst day of 1991, or 10 April
1991. When used on the VIDS/MAF as part of
the job control number, the first position
identifying the year is omitted. All dates used
on source documents are expressed as Julian
Job control number (JCN). A 9- through
11-character alphanumeric code used to separately
identify each maintenance action. This code is
composed of four partsan organization code,
a Julian day, a serial number, and a suffix letter
or number. The first two parts have been
discussed. The serial number is either a three-
character number that runs sequentially from 001
to 999 or a three-character alphanumeric number
with an alphabetic first character, and the last two
numbers running sequentially from 00 to 99.
Three-character sequence numbers are used to
identify routine day-to-day maintenance actions.
An example of this type of JCN is AC4-030- 216.
Three-character alphanumeric serial numbers are
used only to document major inspections other
than preflight, postflight, turnaround, daily,
special, conditional, corrosion, and acceptance/
transfer inspections (discussed later in this
chapter). An example of this type of JCN is
The JCN suffix is an alphanumeric code that
is used by intermediate maintenance activities. It
identifies a subassembly or sub-subassembly
repair action completed separately from the major
component repair action. This suffix is added to
the basic JCN; for example, AC4-030-216-A or
Work unit code (WUC). A one-, three-, five-,
or seven-character numeric or alphanumeric code
that normally identifies the system, subsystem,
and component or part of the end item being
worked on. The first two characters are
standardized and identify the system or the end
item. This block is also used to identify major
inspections that are performed; for example,
030000A is used for a 7- and 14-day special
NOTE: An end item is a final combination
of products, components, parts, etc., with a
designated use. An example of an end item is an
aircraft, a mobile electric power plant, or an
uninstalled aircraft engine.
Action taken code. A one-character alphabetic
or numeric code that describes what maintenance
was performed on an item identified by a WUC.
Manufacturers code. A five-character
numeric or alphanumeric code that identifies the
manufacturer of a component, part, or end item.