00-20-2 Chapter 4

A system of standardized symbols and abbreviations used in maintenance documentation to record and retrieve data. Codes facilitate reporting and help manage maintenance activities.

The REMIS (Reliability and Maintainability Information System) database provides data elements, codes, and compatibility edits for use in maintenance documentation. It serves as the primary source for MDD data.

The TO (Technical Order) provides instructions for documenting maintenance activities, including the use of codes. This information is often found in Chapter 7.

Changes to codes and data elements are proposed through the Recommended Change process outlined in TO 00-5-1. These changes are then reviewed by the PM (Program Manager) TO OPR (Technical Order Operating Representative) and must be approved by HQ AFMC/A4F before implementation.

Work Unit Codes (WUCs) are structured numbers that identify specific maintenance tasks. They are organized hierarchically, with system-level WUCs (first two positions) defining equipment types. Support General WUCs are found in Appendix I of the TO. New WUCs must be approved by HQ AFMC/A4F prior to use.

Job Control Numbers (JCNs) are codes used to track maintenance tasks and work orders. Recommendations for JCNs are forwarded through command channels to HQ AFMC/A4FI for approval.

Workcenter codes are used to identify specific maintenance locations or facilities. Recommendations for changes are forwarded through command channels to HQ AFMC/A4FI.

Narrative information in MDD complements coded data, but must not contain classified data. Such classified information is managed separately in maintenance management information systems.

The workcenter that is primarily responsible for maintaining a piece of equipment.

The workcenter that actually performs the maintenance.

Any workcenter where maintenance personnel are assigned, even if they don't report directly.

A workcenter where maintenance personnel may spend time, but no one is officially assigned there.

Information about where and who performed the maintenance.

Data about maintenance performed by teams from outside the main complex.

Unique code used to identify equipment and generate maintenance data.

The first character in the ID number, usually representing the equipment type.

The last four characters of the ID number, usually matching the last four digits of the equipment's serial number.

Types of ID numbers based on equipment.

ID number assigned to specific types of equipment like aircraft, missiles, and engines.

ID number assigned to specific test equipment.

ID numbers are assigned to individual end items, such as registered and/or powered SE, and non-registered SE selected by local management for ID assignment based on individual serial number.

Grouped ID numbers are assigned to SE not managed by registration or serial number and SE items that don't need detailed MDD data for each item.

All equipment with a grouped ID number must have the same end item WUC (Work Unit Code) and SRD (System Requirements Document) to facilitate consistent maintenance.

Grouped ID numbers can be used for training equipment in AETC technical training centers, allowing for documenting preventive maintenance inspections.

End items containing TMDE (Test, Measurement, and Diagnostic Equipment) components typically require an ID number with the first character being 'B', 'G', or 'H'.

Equipment that is frequently transferred, infrequently maintained, or has low inventory, may not require ID numbers.

End items with an SRD assigned must have an ID number for inventory tracking, even if the equipment is managed by ALC.

Transient aircraft and missile transporters are recorded under transient equipment procedures and don't require ID numbers.

Shop equipment, hand tools, and some nondestructive inspection equipment are generally not assigned ID numbers.

Work performed without an ID number requires a command code entry in the MDD process, as the owning workcenter cannot be identified.

Activities responsible for maintaining ID number assignments are responsible for purging ID numbers no longer required, ensuring accuracy in records.

ID numbers are not used in REMIS or depot maintenance; the equipment designator and complete serial number are used instead.

When an ID number isn't used or hasn't been assigned, the MDS (Maintenance Data System) and/or TMS (Time Management System) are used for tracking maintenance.

The FSC (Federal Stock Class) code is the first four digits of the NSN (National Stock Number) and is used to identify the item being modified or removed.

The first five characters represent the ordinal day of the year (e.g., 96041 for February 10th, 1996). The last four characters are used to identify individual jobs using a daily or monthly sequence number (e.g., 0001 for the first job of the day).

The sixth position of the JCN can be an alpha or numeric character assigned for hourly and calendar phased inspections, with the highest-numbered inspection assigned if multiple phases are happening concurrently.

A block of sequence numbers is reserved for discrepancies discovered during the 'Look' phase of an inspection, ensuring unique JCNs for major issues or those requiring supply orders. Minor discrepancies are completed under the look phase JCN.

To prevent duplication of JCNs, alpha characters are not used in the sixth position of the JCN except in specific cases like TF39 engine JCNs or in cases specified in the Technical Order.

The use of consecutive sequence numbers for discrepancies helps track them easily and retrieve inspection data efficiently. A reserve block of numbers is assigned to ensure unique JCNs are available within the maintenance complex.

Blocks of JCNs can be assigned to equipment, organizations, or recurring maintenance actions according to specific requirements and procedures. Records of JCN assignment can be maintained using the AF Form 861 or the IMDS CDB screen.

A unique identifier assigned to maintenance actions involving the removal of parts from one item to repair another.

The responsibility for assigning and controlling JCNs is outlined in major command implementing instructions, with local procedures for linking related maintenance actions.

An information system used to track and record maintenance actions, including JCNs, hours expended, and parts replaced.

A database that provides contact information for standards and specifications, available online.

A system for managing technical information, including WUC tables and contact information for Equipment Specialists (ESs).

A manual that provides guidance on technical procedures for specific equipment, with WUC tables maintained by Equipment Specialists (ESs).

A system for reporting, controlling, and identifying maintenance actions, ensuring that all related information is linked together.

A publication that provides guidance on general construction and design of Technical Manuals, Standards, and Specifications (TMSS).

WUCs used to categorize general maintenance activities like cleaning, servicing, or inspecting.

The first two characters of a WUC for aircraft, cruise missiles, and ICBMs, indicating the type of system the component is part of.

The first two characters of a WUC for equipment like SE, C-E, ATE, and trainers.

WUCs representing a component slot where different parts with the same function can be installed.

The third and fourth characters of a WUC that identify subsystems or major assemblies.

The fifth character of a WUC, usually identifying reparable items, but there are exceptions for critical parts and structural members.

WUCs ending with a '9' or '99' are used for items not otherwise coded.

Standard procedures and documentation for maintenance activities.

A database providing data, codes, and compatibility edits used in maintenance documentation.

The person responsible for developing WUC tables and documentation.

The acronym for the Air Force Materiel Command.

A unique identifier for a component used for tracking maintenance activities.

A standard specifying requirements for LCNs.

When a WUC/LCN doesn't exist for a specific component, use the WUC/LCN of the next higher assembly instead of leaving it blank.

A unique reference symbol is used for electronics equipment, often a combination of letters and numbers, like 'V101' or 'R101', to identify specific components within a circuit.

When a reference symbol is unavailable, a noun or abbreviation, no longer than nine characters, describing the replaced part can be used.

Indicates the quantity of parts replaced during each repair.

The SRD is a three-character code used to identify equipment and facilitate reporting, accounting, and analytical processes.

An SRD code must be assigned before equipment is fielded so inventory and maintenance reporting is possible.

Components being repaired at a depot should use the SRD found on the AFTO Form 350 tag or its automated version.

Type maintenance code (TMC) is a single character code indicating the type of maintenance performed, like scheduled or unscheduled.

The TMC is stipulated by the assigned SRD code, and specific codes are defined in Appendix D of the TO.

Component position is a single digit code used to identify the position of an engine, engine related item, or egress item.

For R&M analysis, equipment failures should be reported to the fifth character of the WUC whenever possible.

WUCs are used to sort maintenance data and provide a standard method for summarizing different levels of detail.

WUCs combined with the SRD create a flexible and informative data retrieval capability.

A 10-character alphanumeric code used to identify equipment, with no special characters. For certain equipment, like C-E, it's 15 characters.

The total time an item has been in operation, measured in hours for most items. For items with Elapsed Time Indicators (ETIs), it's the ETI reading in hours. For calendar items, it's either days or months.

The complete AFTO Form 350 tag number that is prepared and attached to a removed tracked item.

The part number and lot number (if applicable) of the item being installed. A lot number is required for equipment with an Egress Indicator of B or C.

Includes a detailed description of the problem encountered, including multiple Built-in Test (BIT) fault codes.

A detailed description of the steps taken to fix the problem, including the action taken codes, WUC nomenclature, how malfunctioned code, and units produced.

Statements used when 00 units are placed in the coded line entry, indicating that the maintenance action is on hold due to work stoppage, crew change, or labor change.

Statements used when 01 units are placed in the coded line entry, indicating that the maintenance action on the item is finally accomplished.

Used only when 01 units is placed in the coded line entry, indicating that a support general code with only one tasking towards it is accomplished. Example: 03100 – preflight inspection or TCTO.

Used only when 01 units is placed in the coded line entry to identify that the maintenance action was opened incorrectly or needs to be closed due to an incorrect coding.

Used to document non-reparable or non-recoverable items replaced during on-equipment maintenance actions.

The Federal Supply Classification (FSC) code for the replaced component or part.

The part number of the replaced component or part. If the item has no part number, the reference designator should be entered. For conventional munitions items, the part number from the WUC table is used.

The WUC/LCN of the replaced component or part, if applicable. If not assigned, use the Not Otherwise Coded (NOC) WUC/LCN.

A three-digit code that identifies a general type of maintenance work for a system or component, starting with 05 through 15, excluding 06.

A unique identifier for a specific maintenance action, like removing and replacing a component. These codes are standardized across different equipment types.

Represents the actual time a system or component was used during operations (like flight hours). This helps adjust maintenance scheduling based on actual usage.

The number of identical components or pieces of equipment installed within a larger assembly or system.

A combination of a WUC (Work Unit Code) and an ATC (Action Taken Code) used to describe a specific maintenance action. This combination allows for precise documentation of what was done.

Used when maintenance cannot be linked to a specific component or subsystem. It's used to track overall system or subsystem work.

A code that indicates how a malfunction was discovered, such as during an inspection or functional check.

Used when a specific item being repaired or replaced doesn't have a WUC. The WUC entry is then associated with the next higher assembly.

Used when an inspection or operational check reveals that a reported discrepancy doesn't exist or cannot be duplicated.

Used to report inspection, servicing, or testing of components removed from end items. It is used to track component-level tasks.

Used when troubleshooting activity is being reported separately from a repair action. It helps categorize maintenance into phases.

HMC code assigned when a component does not meet specifications or drawings, signifying a manufacturing or overhaul defect. Used only for items withdrawn from supply stock and not for reporting repair actions on failed items.

HMC codes used to document failure to operate or internal failures. Used only with specific ATC codes for on-equipment and off-equipment reporting respectively.

HMC code used when a component is removed or reinstalled to facilitate maintenance, not because of a defect. Used for gaining access to other components.

HMC code used to document defective wiring systems, including wires, fiber optic lines, connectors, and components like switches or relays. Requires additional information such as failed component number, malfunction cause, and solution.

A unit produced entry indicates a completed maintenance action and is recorded as '1' for completed actions and '0' for partial completion. It is used to track work progress and identify the workcenter responsible for completion.

A unit entry of '1' represents a single completed maintenance action or support general action performed. It identifies how many times the action was carried out.

When a maintenance action is stopped or restarted, use the same Action Taken code throughout, recording units accordingly. For tracked parts, the UP can only be '00' or '1'.

UP entries are limited to two digits. For more than 99 units, use an additional line entry to reflect the additional units completed.

The Category of Labor data element identifies types of man-hours spent. One entry is required if the crew has the same category of labor, but multiple entries are required if more than one category (e.g., military and civilian) is involved or overtime is used.

This data element identifies the command or activity where the maintenance was performed. It helps track where the work occurred and who is responsible.

HMC code for 'Improper Manufacture or Overhaul' when a component does not meet specifications and is withdrawn from supply stock.

HMC codes for 'Failed to Operate' (242) and 'Internal Failure' (374). Used only when reporting on equipment with specific ATC codes.

HMC code for 'No Defect - Component Removed/Reinstalled'. Used when components are removed or reinstalled for access during maintenance, but are not defective themselves.

HMC code for 'Conductive Path Defect/Failure'. Used to document wiring system failures, requiring details about the failed component, location, cause, and solution.

Maintenance actions performed on transient aircraft and equipment without a local ID number require a two-position command code to identify the owning Command.

A locally devised two-position code used to identify special projects, tenant support, cross utilization training, or any other locally required purpose.

When maintenance actions documented in the Integrated Maintenance Data System (IMDS) are incorrect and can't be corrected using normal methods, the activity identifier (AI) is coded as “ER”.

The employee number or USERID identifies the individual who performed the maintenance action. For bases supported by IMDS CDB, a unique five-position employee number or USERID is assigned.

The time entry documents the duration of the maintenance action, including any delays exceeding 15 minutes or changes in crew size or labor category.

The crew size entry indicates the number of individuals from the same workcenter who participated in the maintenance action. A zero is used when documenting inspections.

Systems with built-in test (BIT) fault reporting should document fault codes in the appropriate field or discrepancy narrative.

Master Job Standard Numbers (MJSNs) are used to report inspections, time change items, and serially controlled items. If the first position is an alpha character, the MJSN is standard across weapon systems.

An erroneous documentation problem for NRTS actions is the inclusion of handling time to and from supply. NRTS time should only reflect bench check and paperwork time, not exceeding 10 hours.

The Integrated Maintenance Data System (IMDS) CDB is a database that supports various maintenance functions, including documenting maintenance actions, reporting data, and managing inventory.

The time spent by the supervisor or senior member performing direct labor is reported in the IMDS CDB to contribute to ownership and operation cost computations and maintenance data analysis.

The Reliability and Maintainability Information System (REMIS) is a database that tracks and records maintenance actions, including JCNs, hours expended, and parts replaced.

The first two positions define the equipment type. They create a hierarchical organization for specific maintenance tasks.

These codes are used for TCTO actions, reporting work on items without failure, and identifying the nature of a defect.

These codes identify when a defect or maintenance requirement was discovered. They are used throughout the repair process for all subsequent actions.

This code will always identify the nature of the defect found on the system, subsystem, or component.

Codes 0-9 are used when a part is not repairable at the current location. They differentiate the reason for being unable to repair.

This code is used only when repairs are specifically prohibited by technical orders due to base-level repair restrictions.

This code is used when repair is authorized but cannot be done due to lack of equipment, tools, skills, or facilities.

This code is used when items authorized for base repair are directed to depot facilities by specific authority.

They identify major removal and replacements of items by off-equipment workcenters. These codes are crucial for recording these specific maintenance actions.

This code indicates that a bench check was completed but repair action was deferred.

This code signifies that a bench check was started but not completed.

This refers to the section in the TO that provides instructions for handling a problem that needs further investigation and reporting.

This form is used to document repair actions, including deferred repairs and NRTS codes.

This form is used to identify reparable status and keeps track of repair actions.

A unique numerical code assigned to track maintenance tasks and work orders. It typically includes the year, day of the year, and a sequence number for the specific job within that day.

A grouped JCN is used when multiple maintenance tasks are related and share the same purpose, such as performing several commodity TCTOs (Time Compliance Technical Orders) on a single piece of equipment.

Individual unique JCNs are assigned to single maintenance activities, such as removing and replacing a serially-controlled item or performing engine changes.

The sixth position in a JCN for phased inspections (periodic, hourly, etc.) is assigned an alphabetic character to indicate the specific phase of the inspection. The alphabetic sequence is used to identify the different packages within an inspection cycle. For example, 'A' for the first package, 'B' for the second package, and so on.

A block of sequence numbers is reserved for major discrepancies discovered during inspections. These discrepancies require separate JCNs because they are significant issues, need to be recorded individually, and may require ordering parts from supply.

A specific JCN is assigned to each phase of an inspection. However, it is important to distinguish between the inspection itself and the maintenance actions that result from that inspection. While the JCN for the inspection will be used for all maintenance actions directly tied to it, some maintenance actions may require a separate JCN, even if they were identified during an inspection. For example, maintenance actions addressed in Step 9 of the instructions, which involve ordering parts from supply, will have their own unique JCN, even if they were initially identified during an inspection.

JCNs play a crucial role in tracking and retrieving information about maintenance actions. They provide a unique identifier that allows for easy tracking of any discrepancy or maintenance task. Consecutive sequence numbers ensure efficient tracking and retrieval of maintenance data. A reserve block of numbers is assigned to ensure that unique JCNs are available within the maintenance complex.

JCNs can be assigned to individual pieces of equipment, specific organizations, or recurring maintenance actions. These assignments help ensure that each JCN remains unique and is used consistently. The AF Form 861 and the IMDS CDB screen are used to maintain records of JCN assignments.

A unique JCN is assigned when parts are removed from one item to repair another. This helps track which parts were used and where they came from.

The responsibility for assigning and controlling JCNs is delegated to the individual major commands. They are responsible for establishing procedures that ensure proper JCN usage and maintain the integrity of the maintenance process. Local procedures are also implemented to link related maintenance actions.