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The North American Aviation Part Numbering System: A marvel of ingenuity during one of the most chaotic times in American history

At AirCorps Library and AirCorps Aviation we geek out and obsess about part number methodology. It helps us do our jobs better, and keep digitized part drawings organized. Some aircraft manufacturers during WWII had no apparent part numbering system, while others established complex organizational systems that unleash a wealth of knowledge simply by understanding their unique systems. At AirCorps we always say that North American Aviation "did it right". Their part numbering system was so detailed and well organized that finding a drawing you need is incredibly simple once you understand the structure.

North American Aviation scaled up production of the P-51 Mustang in under 100 days, in addition to building numerous variants of the B-25, AT-6, and T-28 during WWII. This breadth of work required an incredible amount of organization and planning to accommodate the design changes, revisions, drawing updates, and aircraft variants. Because of this, the creation of a comprehensive part numbering system, and the process for giving each part or assembly a part number had to be very intentional. In this blog I will explain the structure of the NAA part numbering system that contains every North American manufactured part utilized on all of their aircraft.


Part Numbers / Assembly Numbers / Drawing Numbers

The terms, part number, assembly number, and drawing number are essentially interchangeable, which can cause some confusion. Individual aircraft parts such as washers, springs, and sheet metal panels were all given part numbers, but so were the larger assemblies that they were a part of. The term "drawing number" comes into play because there is a drawing for each of these parts and assemblies, and the part number for them is listed on the drawing, and is how the drawing is identified.


For example, part number 102-54259 is the the spring used inside the landing gear position indicator switch protector seal used on the P-51. The spring is an individual part, so it makes sense that it has a part number. This spring fits into the larger seal assembly for the landing gear position indicator switch protector. The seal assembly is part number 102-54257, and shows the springs location within the assembly, along with the part numbers of the other individual parts that make up the seal assembly.


Assembly drawings continue to get increasingly complicated as the assemblies increase in size, but all of them still have their own individual part number. This is why there are so many drawings for an aircraft. Not only are there the thousands of drawings and part numbers depicting individual parts, but also thousands more depicting the ways that all those individual parts fit together into larger and larger assemblies!


Where to find a part number on a North American Drawing

North American part numbers are always located in the title block at the bottom right hand corner of the drawing. This was a standard placement for all part drawings amongst WWII manufacturers. The part number is also printed two additional locations of an NAA drawing, on the outside margin, and in the upper left corner of the title block. In the drawing below you can see an example of the different areas on a drawing that a part number can be found.


NAA Part Numbers - A Number in Two Parts!

North American part numbers can easily be identified because they consist of a PREFIX of 1 to 3 digits, followed by a hyphen, and a SUFFIX of 5 to 6 digits. The part number prefix identifies the model of aircraft that the part was originally designed for, whether or not that part was later used on other aircraft. Several NAA prefix examples:

77- and 78-AT-6A
88- and 121-AT-6D
200- and 219-T-28B
226- and 252-T-28C
87- and 100-B-25D
102- and 104-P-51B

For a detailed list of part number prefixes for North American, and other aircraft manufacturers, CLICK HERE.

Part Number Prefixes for the P-51 Mustang  

Since the P-51 is one of the most discussed Warbirds, I thought I should also included a detailed breakdown of the part number prefixes associated with the Mustang. There are 15 prefixes associated with the P-51, some of them more utilized than others. The cart below shows a breakdown of these 15, and which P-51 models each pertains to. This prefix information can be used in conjunction with the part number suffix chart in the "whole bag of suffixes" section below.

P-51 Part Number Prefix:Model of P-51 Prefix Relates To:
83-Mustang Mk


Suffix Details

The suffix of a NAA part number tells you specifics about the part itself. The first two digits of the suffix identify the part by determining the functional group for which it was designed, regardless of its location in the airplane or its method of attachment. For example, a part number in the -58000 series indicates a hydraulic part, while a part number in the -54000 series indicates the part is used in an electrical system. This means that no matter the prefix that is model specific, all the drawing that share a similar suffix deal with the same functional group, but can be for different aircraft. At AirCorps Library we use this part numbering system to categorize our drawings for each model of North American aircraft.

Some NAA suffixes are very specific, and always mean the same thing - such as:

-00001 = Three View Drawing

-00003 = Inboard Profile

-00002 = General Airplane Assembly

-00010 = Markings


Within this system, it's easy to see how several drawings can have an identical part number suffix, with different prefixes that indicate they are for alternative aircraft models, for example:

102-00010 = Markings drawing for P-51B and P-51C

106-00010 = Markings drawing for P-51D and P-51M

108-00010 = Markings drawing for B-25J

117-00010 = Markings drawing for P-51H

121-00010 = Markings drawing for AT-6F

159-00010 = Marking drawing for T-28A

Notice that the suffix stays the same in the markings drawings above, while the prefix indicated model applicability.


The Whole Bag of Part Number Suffixes:

Beyond the very specific suffixes listed above that start with a series of zeros, every other NAA drawing fits into a more general suffix (functional group). The chart below breaks down the suffix groups within the NAA part numbering system. This information is taken directly from North American technical manuals - they were very conscious about providing factory workers and mechanics with the information they needed to educate themselves - what an idea!

-01000 SeriesWind Tunnel Models
-03000 SeriesHandbook Illustrations
-04000 SeriesMockup
-05000 SeriesField Service
-10000 SeriesWing Installation
-11000 SeriesUpper Center Section Assy
-12000 SeriesUpper Outer Panel Assy
-13000 SeriesLower Center Section Assy
-14000 SeriesLower Outer Panel Assy
-15000 SeriesUpper Aileron Assy
-16000 SeriesLower Aileron Assy
-17000 SeriesLeading Edge Airfoil Assy
-18000 SeriesFlap Assy
-19000 SeriesDive Brake Assy
-20000 SeriesEmpennage Install
-21000 SeriesHorizontal Stabilizer Assy
-22000 SeriesElevator Assy
-23000 SeriesVertical Stabilizer Assy
-24000 SeriesRudder Assy
-30000 SeriesBody Group
-31000 SeriesFuselage Cover Install

-31100 SeriesFuselage General Frame Assy
-31800 SeriesCockpit Enclosure Install

-31900 SeriesEngine Mount Assy
-32000 SeriesEngine Nacelle Install
-32100 SeriesEngine Nacelle Frame Assy
-32900 SeriesNacelle Engine Mount Assy
-33000 SeriesLanding Gear Install
-33100 SeriesChassis Assy
-33200 SeriesWheel-Brake Assy
-33300 SeriesFairing Assy
-33400 SeriesBrake Control Install
-33500 SeriesRetracting Mechanism Install
-33900 SeriesSki Install
-34000 SeriesAuxiliary Landing Gear Install
-34100 SeriesChassis Assy
-34200 SeriesWheel-Brake Assy
-34300 SeriesFairing Install
-34400 SeriesBrake Control Install
-34500 SeriesRetracting Mechanism Install
-34900 SeriesSki Install
-35000 SeriesMain Float Install
-35100 SeriesMain Float Assy
-36000 SeriesWing Tip Float Install
-36100 SeriesWing Tip Float Assy
-37000 SeriesHull Assy
-39000 Series
Fuselage Dive Flaps Install
-40000 SeriesPowerplant Install
-41000 SeriesEngine Assy
-42000 SeriesEngine Accessories Install
-43000 SeriesEngine Control Install
-44000 SeriesPropeller Assy
-45000 SeriesStarting Install
-46000 SeriesCooling Install
-47000 SeriesLubricating System Install
-48000 SeriesFuel System Install
-49000 SeriesAuxiliary Propulsion
-50000 SeriesFixed Equipment
-51000 SeriesInstrument Install
-52000 SeriesSurface Control Install
-52100 SeriesControl Stick or Wheel Install
-52200 SeriesElevator Control Install
-52300 SeriesAileron Control Install
-52400 SeriesRudder Control Install
-52500 SeriesTrim Tab Control Install
-52600 SeriesSlot & Flap Control Install
-52700 SeriesDive Brake Control Install
-53000 SeriesFurnishing Install
-53300 SeriesHeating & Ventilating Install
-54000 SeriesElectrical Equipment Install
-55000 SeriesMooring - Towing, Handling Gear Install
-56000 SeriesCatapult & Arresting Gear Install
-57000 SeriesFloatation Gear Install
-58000 SeriesHydraulic System Install
-60000 SeriesArmament
-61000 SeriesFixed Gun Install
-62000 SeriesFlexible Gun Install
-63000 SeriesBomb Install
-64000 SeriesTorpedo Install
-65000 SeriesPyrotechnics Install
-66000 SeriesGun Camera Install
-67000 SeriesTow Target Install
-68000 SeriesRocket Install
-70000 Series
-71000 SeriesCommunication Equipment Install
-72000 SeriesAvigation Equipment Install
-73000 SeriesMiscellaneous Equipment Install

-73100 SeriesPhotographic Equipment Install
-73300 SeriesOxygen Equipment Install
-73500 SeriesSafety Equipment Install
-73700 SeriesGlider Towing Equipment Install
-80000 Series
-89000 SeriesSpecial Project Kits



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