The ATA chapter system

The map of every manual

The ATA chapter system is the standard numbering scheme used throughout commercial aviation to organise technical documentation. Whether you are reading an aircraft maintenance manual (AMM), fault isolation manual (FIM), troubleshooting manual (TSM) or wiring diagram manual (WDM), the chapter structure remains consistent. Learning this system is one of the fastest ways to navigate aircraft technical publications efficiently.

One numbering scheme for every manual

Aircraft manufacturers organise their technical data according to an industry standard that originated as ATA Specification 100 and is now maintained under ATA iSpec 2200. Thanks to this standardisation, major aircraft systems are assigned the same chapter numbers across manufacturers and document types.

For example, chapter 32 always refers to landing gear, whether you are working on a Boeing or Airbus aircraft, and regardless of whether you are using a maintenance, troubleshooting or fault isolation manual.

Chapter, section, subject

ATA references are typically written in a chapter-section-subject format. This structured numbering makes it easy to locate information quickly and consistently across different manuals. Taking 32-41-00 as an example:

• 32 is the chapter: landing gear.
• 41 is the section: wheels, within the wheels and brakes group (32-40).
• 00 is the subject: general.

Aircraft general (chapters 05 to 12)

The ATA chapters are broadly divided into four major groups. The first covers routine maintenance and ground handling activities, including:

• Time limits and maintenance checks
• Aircraft dimensions
• Lifting and shoring
• Levelling and weighing
• Towing and taxiing
• Parking and storage
• Placards and markings
• Servicing

Airframe systems (chapters 20 to 49)

These chapters contain the aircraft's operational systems, including:

• Standard practices (20)
• Air conditioning (21)
• Auto flight (22)
• Communications (23)
• Electrical power (24)
• Hydraulic power (29)
• Landing gear (32)
• Auxiliary power unit (49)

Structures (chapters 51 to 57)

These chapters cover the aircraft's structural components:

• Structural standard practices (51)
• Doors (52)
• Fuselage (53)
• Nacelles and pylons (54)
• Stabilizers (55)
• Windows (56)
• Wings (57)

Powerplant (chapters 60 to 67 and 70 to 84)

These chapters focus on propulsion systems, including:

• Propeller and rotor standard practices (60) and propellers (61)
• Power plant general (71)
• Engine fuel and control (73)
• Ignition (74)
• Starting (80)

ATA chapters worth memorising

The following chapters appear frequently in maintenance, troubleshooting and technical discussions. A strong familiarity with these chapter numbers will significantly reduce the time needed to locate information during maintenance and troubleshooting tasks.

• 21: Air conditioning
• 22: Auto flight
• 23: Communications
• 24: Electrical power
• 26: Fire protection
• 27: Flight controls
• 28: Fuel
• 29: Hydraulic power
• 30: Ice and rain protection
• 31: Indicating and recording systems
• 32: Landing gear
• 33: Lights
• 34: Navigation
• 35: Oxygen
• 36: Pneumatic
• 38: Water and waste
• 49: Auxiliary power unit (APU)

Key takeaways

• The ATA chapter system uses a standard chapter-section-subject numbering format across all aircraft technical manuals.
• ATA numbering is consistent between manufacturers, making documentation easier to navigate.
• The main chapter groups are 05 to 12 aircraft general, 20 to 49 airframe systems, 51 to 57 structures, and 60 to 67 plus 70 to 84 powerplant.
• Memorising frequently used chapters, especially 21 to 36 and 49, will make technical manual navigation much faster and more efficient.