Quick answer
ATA chapters are a standard numbering system that groups aircraft documentation and equipment by system, such as 32 for landing gear or 34 for navigation. The system began as ATA Spec 100 and is now maintained in ATA iSpec 2200 by Airlines for America. Adding the ATA chapter to a parts request helps everyone place the part in its system context quickly.
Where ATA chapters come from
ATA Spec 100 standardized how manufacturers organized maintenance documentation. Airlines for America states that Spec 100 and Spec 2100 were merged into iSpec 2200 in 2000 and that Spec 100 has not been updated beyond its 1999 revision. People still say “ATA 100 chapters” for the numbering.
The FAA’s Joint Aircraft System/Component code, used in service difficulty reporting, is a modified version of ATA Spec 100. Exact chapter titles vary slightly between documents, so the titles below are common forms rather than verbatim iSpec 2200 wording.
Airframe systems: chapters 21 to 49
These chapters cover the aircraft’s systems and are where most component requests fall.
- 21 Air Conditioning · 22 Auto Flight · 23 Communications · 24 Electrical Power
- 25 Equipment/Furnishings · 26 Fire Protection · 27 Flight Controls · 28 Fuel
- 29 Hydraulic Power · 30 Ice and Rain Protection · 31 Indicating/Recording Systems
- 32 Landing Gear · 33 Lights · 34 Navigation · 35 Oxygen · 36 Pneumatic
- 38 Water/Waste · 45 Central Maintenance System · 49 Airborne Auxiliary Power
Structures, propellers, and engines: chapters 51 to 80
Structural chapters cover the airframe itself; the power plant chapters cover engines and their systems.
- 51 Standard Practices/Structures · 52 Doors · 53 Fuselage · 54 Nacelles/Pylons
- 55 Stabilizers · 56 Windows · 57 Wings · 61 Propellers
- 71 Power Plant · 72 Engine · 73 Engine Fuel and Control · 74 Ignition · 75 Air
- 76 Engine Controls · 77 Engine Indicating · 78 Exhaust · 79 Oil · 80 Starting
Using ATA chapters in a parts request
General chapters such as 05 Time Limits/Maintenance Checks, 11 Placards and Markings, and 12 Servicing organize documentation rather than equipment. For parts, the system chapters are the useful ones.
An ATA chapter does not replace an exact part number, but it gives context: a 32 landing gear request signals different handling, records, and urgency than a 25 furnishings item. Include the chapter, the part number, and the aircraft type, and the sourcing desk can route the request faster.
Frequently asked questions
What are ATA chapters?
ATA chapters are standard numbers that group aircraft documentation and equipment by system, such as 32 for landing gear, 34 for navigation, and 72 for the engine.
Is ATA 100 still current?
The numbering is still widely used, but Airlines for America says ATA Spec 100 was merged into iSpec 2200 in 2000 and has not been updated since its 1999 revision.
Which ATA chapter covers flight data recorders?
Recorders generally fall under chapter 31, Indicating/Recording Systems.
Authoritative sources
This guide provides general procurement information and is not legal, customs, engineering, or airworthiness advice.
Airlines for America: iSpec 2200, Information Standards for Aviation Maintenance FAA: Joint Aircraft System/Component Code Table and Definitions