Illustrated parts breakdowns and RPSTLs, explained

A repair parts and special tools list (RPSTL) or illustrated parts breakdown (IPB) is the part of a technical manual (TM) that pairs illustrations with numbered lists of the parts a maintainer may replace and order. Army standards use the first name and the Naval Air Systems Command (NAVAIR) the second. MIL-STD-40051-2C, the Department of Defense (DoD) standard for page-based TMs dated December 15, 2015, says the RPSTL authorizes requisitioning, issue, and disposition of parts according to their source, maintenance, and recoverability (SMR) codes. NAVAIR's MIL-STD-3001-8A, with Change 1 dated December 1, 2016, says IPB data serves maintenance support, requisition, storage, authority for use, and identification of parts.

Where the parts list sits

Appendix F of MIL-STD-40051-2C allows RPSTL data in a separate RPSTL TM, in work packages inside a maintenance TM, or in a depot or national maintenance work requirement. Inside a maintenance TM, the parts chapter immediately follows the last maintenance chapter. The chapter runs in a set order: one introduction work package, one or more repair parts list work packages, then, when needed, special tool repair parts, kits, bulk items, and special tools lists. A National Stock Number (NSN) index and a part number index close it, plus a reference designator index when specified.

DA Pam 25-40, the Army publishing procedures dated February 1, 2024, says RPSTLs other than interactive electronic technical manuals (IETMs) are normally published at the -12P level. In an IETM, the RPSTL is combined with the maintenance coverage.

MIL-STD-3001-8A sets the NAVAIR order: an introduction work package numbered 001 00, an alphabetical index (002 00), a numerical index of part numbers (002 01), a numerical index of reference designations (002 02), and then the group assembly parts lists (GAPLs) and their figures, starting at 003 00.

Figures and item numbers

RPSTL figures are numbered in one sequence through the whole RPSTL, starting at 1, instead of restarting in each work package. For complex equipment, each repair parts list work package holds one figure and one parts list. The figure title, the functional group title, and the matching maintenance allocation chart (MAC) title must be the same, and titles come from provisioning documentation when it exists. Each list entry carries the callout number shown on the figure, in ascending order. Dots in the description show each part's next higher assembly, with no more than five levels.

The NAVAIR standard calls these index numbers. They begin at 1, are assigned first in the GAPL and then applied to the illustration, and must agree between the two. A part number listed twice in one breakdown gets two index numbers. On a circuit card assembly, numbering starts at the top left corner and runs clockwise. The part number index gives a location as figure, then index number, as in "F0041-00/17."

When an item fits only some models, a three-position usable on code (UOC) sits under its description, such as the standard's sample PAA for Model M114. NAVAIR IPBs use capital letters instead, doubled when single letters run out, never O or I.

The SMR code and the other columns

The prescribed RPSTL introduction lists the columns: item number, SMR code, NSN, Commercial and Government Entity code (CAGEC), part number, description with UOC, and quantity per figure. The SMR code follows Army Regulation (AR) 700-82.

Position	What it tells the maintainer	Codes in MIL-STD-40051-2C
1 and 2	How to get the item	P codes for stock items, K for kit parts, M for made from bulk, A for assembled, X codes such as XA and XD
3	Lowest level that may remove, replace, and use it	C crew, F maintainer, H below depot sustainment, L specialized repair activity, D depot (aviation: O, F, L, D)
4	Lowest level that can do complete repair	Same letters, plus Z nonreparable and B no repair
5	Who decides disposition when unserviceable	For example Z, F, H, L, D, and A for special handling

The Defense Logistics Agency (DLA) describes the NSN as 13 digits: a four-digit Federal Supply Classification (FSC) and a nine-digit National Item Identification Number (NIIN). The first two NIIN digits name the assigning country; 00 and 01 both mean the United States. The standard describes the CAGEC as a five-digit code for the manufacturer, distributor, or Government activity that supplies the item. The part number belongs to the organization that controls the item's design, and an item ordered by NSN may arrive under a different part number.

From a figure to an order

The RPSTL introduction prescribes the lookup. With neither NSN nor part number in hand, the maintainer finds the assembly group in the table of contents, opens the figure for that functional group, notes the item's number, and reads that figure and item number in the parts list, where the NSN and part number sit on the same line. With an NSN, the search starts in the NSN index, sorted by NIIN; with a part number, in the part number index.

The source code then shapes the order. P-coded items are ordered by NSN. Kit parts are not ordered singly; the whole kit is. An XA item is never ordered; its next higher assembly is. XB items not available from salvage, and XD items with no NSN, are ordered by CAGEC and part number. A non-aviation field RPSTL lists only parts coded F in the third position, so item numbers can skip.

The Navy's Naval Aviation Maintenance Program (NAMP), dated October 28, 2024, says manufacturers prepare IPBs to help supply and maintenance personnel identify and order replacement parts. MIL-STD-3001-8A names the Naval Inventory Control Point (NAVICP) P2300 series as the source for the most current codes, which NAVAIR writes SM&R, and calls for a manual update when they differ.

What to check

• Do the figure title, functional group title, and MAC title match, as MIL-STD-40051-2C requires?
• Does every callout on the figure appear in the list under the same number?
• What does the source code call for: an NSN, the whole kit, the next higher assembly, or a CAGEC and part number?
• Does the third SMR position authorize the level doing the work?
• Is the usable on code right for the model on hand?
• For a NAVAIR IPB, do the SMR codes match the current NAVICP P2300 listing?

Azcuna's TRACE is one offline viewer for S1000D, MIL-STD-3001 XML, and PDF technical manuals. It keeps the source location and the markings of everything it shows and never modifies the source. It was proposed to NAVAIR under Navy SBIR Phase I topic DON26BZ05-NV078, and the proposal was submitted on September 23, 2026.

Sources

1. 1MIL-STD-40051-2C, Preparation of Digital Technical Information for Page-Based Technical Manuals (TMs) · Department of Defense, December 15, 2015, via EverySpec
2. 2MIL-STD-3001-8A (w/Change 1), Illustrated Parts Breakdown (IPB) (Part 8 of 8 Parts) · Department of the Navy, December 1, 2016, via EverySpec
3. 3DA Pam 25-40, Army Publishing Program Procedures · Headquarters, Department of the Army, February 1, 2024
4. 4National Stock Numbers (NSNs) · Defense Logistics Agency Disposition Services
5. 5The Naval Aviation Maintenance Program (NAMP), COMNAVAIRFORINST 4790.2E, 28 Oct 2024 · Commander, Naval Air Forces, posted by Naval Air Systems Command

Where this shows up in our work

• TRACE, the offline S1000D and IETM viewer opens S1000D, MIL-STD-3001 and PDF technical manuals on a tablet with every marking intact.
• ELLMENT, the offline LLM for E-2D crews answers a crew's question from the aircraft's own manuals and cites the page, with no network.