Understanding aircraft parts is not just about finding the right component — it’s about knowing how parts are classified, approved, and sourced. If you’ve ever searched for a part using an ATA chapter, wondered what PMA means, or tried to decide between OEM and PMA parts, you’re not alone. These are some of the most common questions in aviation maintenance and sourcing.
This guide explains everything in a simple way. You’ll learn how ATA chapters work, what PMA aircraft parts are, and how they compare to OEM parts — so you can make better decisions when buying or selling aircraft components.
Aircraft Parts Guide:
ATA Chapters, PMA Meaning & OEM vs PMA Explained
When working with aircraft parts, you’ll often see terms like ATA chapters, PMA, and OEM—but they’re not always easy to understand at first. These concepts play a big role in how parts are classified, approved, and sourced across the aviation industry.
Whether you’re searching for a part by ATA chapter, comparing OEM and PMA options, or trying to understand what PMA really means, this guide breaks it down in a simple and practical way.
By the end, you’ll have a clear view of how aircraft parts are organized and how to choose the right components with confidence.
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What Are ATA Chapters?
ATA chapters are a standardized system used in aviation to organize aircraft systems and components.
They were created by the Air Transport Association (ATA) to make it easier for maintenance teams, engineers, and suppliers to identify and locate parts quickly.
Every aircraft system is assigned a chapter number. This allows everyone in the industry to speak the same “technical language.”
Why ATA Chapters Matter
ATA chapters help simplify complex aircraft systems by grouping parts into clear categories.
They are used for:
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Maintenance manuals
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Parts catalogs
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Troubleshooting
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Inventory management
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Aircraft documentation
When buyers search for parts, they often use ATA chapters to narrow down results faster.
ATA Chapters List (Common Examples)
Here are some of the most commonly used ATA chapters:
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ATA 21 – Air Conditioning
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ATA 22 – Auto Flight
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ATA 23 – Communications
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ATA 24 – Electrical Power
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ATA 25 – Equipment / Furnishings
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ATA 27 – Flight Controls
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ATA 28 – Fuel System
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ATA 29 – Hydraulic Power
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ATA 30 – Ice & Rain Protection
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ATA 32 – Landing Gear
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ATA 33 – Lighting
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ATA 34 – Navigation
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ATA 35 – Oxygen
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ATA 36 – Pneumatic
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ATA 38 – Water / Waste
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ATA 49 – Auxiliary Power Unit (APU)
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ATA 52 – Doors
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ATA 53 – Fuselage
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ATA 57 – Wings
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ATA 71–80 – Engine Systems
Using ATA chapters helps buyers quickly find the exact category of parts they need, especially when working with large inventories.
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What Is PMA in Aviation?
PMA stands for Parts Manufacturer Approval.
It is an approval issued by aviation authorities (such as the FAA) that allows a manufacturer to produce replacement aircraft parts.
PMA parts are designed to meet the same safety and performance standards as original manufacturer parts.
What Are PMA Aircraft Parts?
PMA aircraft parts are aftermarket components that are:
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Approved by aviation authorities
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Manufactured by certified companies
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Tested for safety and performance
They are commonly used as alternatives to OEM parts, especially when cost or availability is a concern.
Why PMA Parts Are Used
PMA parts are widely used in aviation for several reasons:
Cost Savings
PMA parts are often more affordable than OEM parts while still meeting regulatory standards.
Availability
They can be easier to source, especially when OEM parts have long lead times.
Performance Improvements
Some PMA manufacturers improve the original design, offering better durability or efficiency.
Are PMA Parts Safe?
Yes — PMA parts must meet strict certification requirements before they can be approved.
They go through:
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Engineering review
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Testing and validation
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Regulatory approval
This ensures they are safe and compliant for aircraft use.
What Are OEM Aircraft Parts?
OEM stands for Original Equipment Manufacturer.
OEM parts are produced by the original manufacturer of the aircraft or its components.
These parts are identical to what was installed on the aircraft when it was first built.
OEM vs PMA Aircraft Parts
One of the most common questions in aviation is whether to choose OEM or PMA parts.
Here’s a simple comparison:
OEM Parts
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Made by the original manufacturer
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Fully aligned with original aircraft design
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Often higher cost
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Trusted brand reputation
PMA Parts
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Made by approved third-party manufacturers
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Must meet the same safety standards
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Usually more cost-effective
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Sometimes improved design
Which One Should You Choose?
The right choice depends on your needs.
Choose OEM if:
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You want original manufacturer parts
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You follow strict OEM-only policies
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You prioritize brand consistency
Choose PMA if:
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You want to reduce costs
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You need faster availability
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You are open to approved alternatives
In most cases, both options are safe — as long as the parts are properly certified and traceable.
How ATA Chapters, PMA, and OEM Work Together
These three concepts are closely connected in real-world aviation operations.
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ATA chapters help you find the right category of parts
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PMA and OEM define how the part is manufactured and approved
For example:
You might search under ATA 32 (Landing Gear) and then choose between OEM or PMA parts based on availability, price, and preference.
Why This Matters for Buyers
Understanding these concepts helps you:
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Find parts faster
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Compare options more effectively
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Avoid sourcing mistakes
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Make confident purchasing decisions
It also helps you communicate better with suppliers and maintenance teams.
Why This Matters for Sellers
For sellers, using ATA chapters and clearly stating OEM or PMA status improves:
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Search visibility
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Buyer trust
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Listing performance
Buyers are far more likely to engage with listings that are structured and easy to understand.
How Aviatrading.com Helps
Aviatrading.com is built to support how aviation professionals actually search and trade parts.
Our platform allows you to:
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Search by ATA chapter
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Filter by part type and condition
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View certification details clearly
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Connect directly with sellers
This makes it easier to find the right parts and make informed decisions.
Full ATA chapter list
The ATA numbering system, defined in ATA 100 and carried forward into iSpec 2200, is the common language of aircraft maintenance and parts procurement. Every technical publication, every parts catalogue and every well-written RFQ references it. Sourcing a component without naming its chapter is how buyers end up quoting against the wrong system.
General and pre-system chapters
| 05 | Time Limits and Maintenance Checks | 12 | Servicing |
| 06 | Dimensions and Areas | 14 | Hardware |
| 07 | Lifting and Shoring | 18 | Vibration and Noise Analysis |
| 08 | Levelling and Weighing | 20 | Standard Practices — Airframe |
| 09 | Towing and Taxiing | ||
| 10 | Parking, Mooring, Storage and Return to Service | ||
| 11 | Placards and Markings |
Aircraft systems (ATA 21–49)
| 21 | Air Conditioning | 36 | Pneumatic |
| 22 | Auto Flight | 37 | Vacuum |
| 23 | Communications | 38 | Water and Waste |
| 24 | Electrical Power | 41 | Water Ballast |
| 25 | Equipment and Furnishings | 42 | Integrated Modular Avionics |
| 26 | Fire Protection | 44 | Cabin Systems |
| 27 | Flight Controls | 45 | Central Maintenance System |
| 28 | Fuel | 46 | Information Systems |
| 29 | Hydraulic Power | 47 | Nitrogen Generation System |
| 30 | Ice and Rain Protection | 48 | In-Flight Fuel Dispensing |
| 31 | Indicating and Recording Systems | 49 | Airborne Auxiliary Power (APU) |
| 32 | Landing Gear | ||
| 33 | Lights | ||
| 34 | Navigation | ||
| 35 | Oxygen |
Structures (ATA 50–57)
| 50 | Cargo and Accessory Compartments | 54 | Nacelles and Pylons |
| 51 | Standard Practices and Structures | 55 | Stabilizers |
| 52 | Doors | 56 | Windows |
| 53 | Fuselage | 57 | Wings |
Propeller and rotor (ATA 60–67)
| 60 | Standard Practices — Propeller and Rotor | 64 | Tail Rotor |
| 61 | Propellers and Propulsors | 65 | Tail Rotor Drive |
| 62 | Main Rotor | 66 | Folding Blades and Pylon |
| 63 | Main Rotor Drive | 67 | Rotors Flight Control |
Chapters 60 to 67 are the rotorcraft block. Operators sourcing helicopter parts should quote these numbers directly — main rotor drive and tail rotor drive components in particular are frequently mis-quoted when only a part number is given.
Power plant (ATA 70–85)
| 70 | Standard Practices — Engine | 78 | Exhaust |
| 71 | Power Plant | 79 | Oil |
| 72 | Engine | 80 | Starting |
| 73 | Engine Fuel and Control | 81 | Turbines |
| 74 | Ignition | 82 | Water Injection |
| 75 | Air | 83 | Accessory Gearboxes |
| 76 | Engine Controls | 84 | Propulsion Augmentation |
| 77 | Engine Indicating | 85 | Fuel Cell System |
How to use ATA chapters when sourcing parts
- Quote the chapter in every request. It removes an entire class of ambiguity before the first reply arrives.
- Use it to structure inventory. Stock organised by ATA chapter is searchable by every buyer in the industry; stock organised by internal category is searchable by nobody.
- Use it to spot coverage gaps. Mapping your rotable pool against chapters shows immediately which systems have no spare cover.
- Use it to route enquiries. Chapters 21 to 49 and 70 to 85 need very different technical judgement; sending both to the same buyer slows everything down.
Catalogue listings on Aviatrading are organised on this axis, so a request that names its chapter reaches the sellers who actually hold that category of stock.
PMA and OEM: where to read the full comparison
PMA and the OEM-versus-PMA decision are covered in depth on a dedicated page: PMA parts vs OEM parts — cost, certification, benefits and concerns, which sets out how a PMA is granted, where the savings come from and why lease agreements often restrict them.
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Start Finding the Right Aircraft Parts
Aircraft parts sourcing becomes much easier when you understand how the system works.
ATA chapters give structure.
PMA parts offer flexibility.
OEM parts provide original design assurance.
When combined with proper certification and traceability, these tools help you source aircraft parts safely, efficiently, and with confidence.
Whether you’re searching by ATA chapter or comparing OEM and PMA options, having access to the right marketplace makes all the difference.
Explore listings, compare options, and connect with trusted aviation suppliers on Aviatrading.com — and take control of your aircraft parts sourcing process.
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