Why approved data matters
Under CAR-145 and EASA Part-145, maintenance must be carried out using current, approved maintenance data. When you sign a task card or issue a certificate of release to service, you are confirming that the work was done in accordance with that data — not from memory, not from a colleague’s shortcut and not from an old photocopy. The documents below are the tools that make that possible.
The ATA chapter system
Most manufacturer manuals are organised by the ATA iSpec 2200 numbering system (developed from the older ATA 100). A reference such as 32-41-00 reads as chapter–section–subject: chapter 32 is Landing Gear, section 41 covers wheels and brakes, and so on. Learning the common chapters makes navigation fast: 05 Time Limits and Maintenance Checks, 12 Servicing, 20 Standard Practices, 21 Air Conditioning, 24 Electrical Power, 27 Flight Controls, 28 Fuel, 29 Hydraulic Power, 32 Landing Gear, 34 Navigation, 49 Airborne Auxiliary Power and 71–80 for the powerplant.
The main manuals
| Document | What it is used for |
|---|---|
| AMM — Aircraft Maintenance Manual | Servicing, removal and installation, adjustment, testing and inspection tasks for systems and components fitted to the aircraft. |
| IPC / IPD — Illustrated Parts Catalogue | Identifying part numbers, interchangeability and quantities, with exploded diagrams. |
| SRM — Structural Repair Manual | Allowable damage limits and approved standard repairs for the airframe structure. |
| CMM — Component Maintenance Manual | Workshop testing, repair and overhaul of a removed component, issued by the component manufacturer. |
| WDM / AWM — Wiring Diagram Manual | Wiring diagrams, connector and wire lists, and equipment locations. |
| SSM — System Schematics Manual | Simplified system schematics that help you understand how a system works. |
| FIM / TSM — Fault Isolation / Troubleshooting Manual | Step-by-step fault isolation from a fault message or symptom to the likely cause. |
| MPD and AMP | The manufacturer’s Maintenance Planning Document and the operator’s approved Aircraft Maintenance Programme, which schedule inspections and tasks. |
| MEL and CDL | The Minimum Equipment List and Configuration Deviation List, which define what may be inoperative or missing for dispatch. |
Effectivity and revision status
Two checks come before any task. First, effectivity: many procedures differ between aircraft of the same type depending on serial number, modification status or installed equipment, so confirm the task applies to the airframe in front of you. Second, revision status: manuals are revised regularly and temporary revisions can change a procedure overnight. Work from the controlled electronic system or the current controlled copy — a printout in a toolbox is uncontrolled the moment it leaves the printer.
From manual to task card
In practice most engineers meet the manuals through task cards and work packages. Planning builds these from the maintenance programme and references the relevant AMM tasks; the engineer stamps each step as it is completed and records measurements and the parts fitted. Where the programme calls for an independent or duplicate inspection — typical for flight controls and engine controls — a second authorised person verifies the work before it is signed off.
Golden rule: if the approved data does not cover what you have found — damage outside SRM limits, a part not listed in the IPC, a procedure that does not match the aircraft — stop and raise it. The answer is an engineering disposition or an approved repair, never an improvised solution.
Where this appears in your licence exams
Maintenance documentation is examined in Module 7 (Maintenance Practices), and the legal framework behind it — approved data, certification and continuing airworthiness — is covered in Module 10 (Aviation Legislation). Expect questions on ATA chapters, on which manual to use for a given job, and on the difference between mandatory and recommended information.
Engineers who are fluent with the manuals work faster, make fewer errors and earn trust quickly. It is a skill worth practising from your very first day in the hangar.