FAA A&P ACS Syllabus Guide: Complete Breakdown

1. Introduction to the Aviation Mechanic ACS

The Aviation Mechanic Airman Certification Standards, published by the FAA as FAA-S-ACS-1, is the authoritative framework for all A&P mechanic certification in the United States. It replaced the older Practical Test Standards (FAA-S-8081 series) and introduced a modern, task-based structure aligned with how the FAA actually tests mechanics — both on the computer-based knowledge tests and in the oral/practical test with a Designated Mechanic Examiner (DME). Whether you are pursuing an Airframe rating, a Powerplant rating, or both, the knowledge requirements defined in the ACS form the foundation of your examination journey.

Understanding the ACS is critical because FAA examiners and DMEs design every question to test specific elements within this document. If you know the ACS structure, you know exactly what to study — and more importantly, what not to waste time on. The ACS eliminates guesswork from your preparation strategy.

The ACS is organized into three sections — AM.I (General),AM.II (Airframe), and AM.III (Powerplant) — each containing subject areas with specific tasks. Each task lists the knowledge elements and risk elements candidates must master. The ACS also includes the certification prerequisites (18 years old, able to read/write/speak English, FAA Form 8610-2 experience documentation) and references the official study materials: 14 CFR Parts 1, 21, 39, 43, 65, 91, 145, and 147, the FAA AMT Handbooks (FAA-H-8083-30 General, -31 Airframe, -32 Powerplant), and AC 43.13-1B.

For a broader overview of the A&P certification process, including how the ACS fits into the bigger picture, see our guide on how to become an A&P mechanic in the USA.

2. Section AM.I: General

The General section of the ACS is the foundation of mechanic certification. It covers the knowledge and skills every mechanic needs regardless of rating. The General knowledge test (AMG) contains 60 questions and must be completed within 2 hours. A score of 70% is required to pass. The General material also appears throughout the Airframe and Powerplant tests, so mastering AM.I pays off across all three exams.

Subject areas in AM.I include:

• Mathematics: Arithmetic, algebra, geometry, and the calculations used in maintenance — ratios, percentages, areas, volumes, and temperature conversions. Weight & balance math appears in this area and again in its own subject.
• Physics: Force, work, power, energy, simple machines, and fluid mechanics. Understanding how levers, gears, pulleys, and hydraulic systems behave is essential for both the exam and the hangar.
• Basic Electricity: Ohm's law, Kirchhoff's laws, AC/DC theory, inductance, capacitance, impedance, and power calculations. Series and parallel circuits, voltage dividers, and the effects of temperature on components.
• Aircraft Drawings: Reading and interpreting blueprints, schematic diagrams, wiring diagrams, and engineering drawings. Symbols, line types, dimensioning, and title block information.
• Weight and Balance: Performing weight and balance calculations, empty weight and center of gravity (CG) determination, loading computations, and the effect of CG on aircraft performance and control.
• Materials and Processes: Aircraft metals (aluminum alloys, steels, titanium), composites, wood, and fabric. Heat treatment, hardness testing, and the properties that determine material selection in aircraft construction.
• Fluid Lines and Fittings: Rigid and flexible fluid lines, fittings, hoses, and the identification, fabrication, and installation standards for hydraulic and pneumatic plumbing.
• Cleaning and Corrosion Control: Corrosion types, causes, and prevention. Cleaning agents and processes, corrosion removal, and protective finishes.
• Ground Operations and Servicing: Ground handling, towing, jacking, fueling and defueling, and engine starting procedures. Safety practices around aircraft and ground equipment.
• Regulations and Publications (14 CFR): This is one of the most heavily tested areas. It covers 14 CFR Part 43 (maintenance, preventive maintenance, rebuilding, alteration), Part 65 Subpart D (mechanic certification, ratings, privileges), Part 91 (inspections and records), Part 39 (Airworthiness Directives), and the role of publications like AC 43.13-1B, FAA Form 337, and the AMT Handbooks.
• Mechanic Privileges and Limitations: What an A&P mechanic may and may not do — return-to-service authority under §43.7, 100-hour inspection authority, and the limits imposed by ratings.
• Human Factors: The physiological and psychological factors that affect maintenance performance — fatigue, stress, complacency, communication, and the "dirty dozen" of maintenance errors.

The General section is often considered one of the most challenging because it requires precise knowledge across a very broad range of topics — from regulatory language to physics calculations. The FAA expects you to know not just the general concept but the specific requirements, including section numbers and conditions. For a dedicated deep dive into the regulations portion, read our complete FAA regulations guide.

3. Section AM.II: Airframe

The Airframe section of the ACS covers the structures, systems, and components that make up the aircraft airframe. The Airframe knowledge test (AMA) contains 100 questions and demands a thorough understanding of both theory and practical maintenance practices. Airframe candidates must demonstrate mastery of every task in this section during the oral/practical test.

Subject areas in AM.II include:

• Airframe Structures — Wood: Wooden aircraft construction, wood defects, adhesives, and repair techniques for wood structures.
• Airframe Structures — Aircraft Covering: Fabric covering systems, doping, inspection of fabric condition, and repair of fabric-covered surfaces.
• Airframe Structures — Aircraft Finishes: Painting systems, finish defects, surface preparation, and application of protective finishes.
• Airframe Structures — Sheet Metal and Non-Metallic Structures: Sheet metal layout, forming, riveting, and fasteners. Composite structures including fiberglass and carbon fiber repair, bonding, and inspection. This is a heavily tested area.
• Airframe Structures — Welding: Welding principles, weld inspection, brazing, and soldering. Identifying weld defects and acceptable weld quality.
• Airframe Structures — Assembly and Rigging: Aircraft assembly, alignment, flight control rigging, and symmetry checks. Cable tensioning and control travel verification.
• Airframe Structures — Airframe Inspection: The scope and methods of airframe inspections, including the use of Appendix D to Part 43, NDT methods (dye penetrant, magnetic particle, eddy current, ultrasonic), and corrosion inspections.
• Airframe Systems — Aircraft Electrical Systems: Aircraft wiring, connectors, circuit protection, bonding and grounding, and electrical load analysis. Wiring inspection and repair standards.
• Airframe Systems — Aircraft Instrument Systems: Pitot-static systems, gyroscopic instruments, electronic flight instruments, and instrument system testing.
• Airframe Systems — Communication and Navigation Systems: VHF, HF, VOR, ILS, DME, ADF, GPS, transponders, and weather radar. Installation and testing of avionics equipment.
• Airframe Systems — Hydraulic and Pneumatic Power Systems: Hydraulic pumps, actuators, valves, accumulators, filters, and fluids. Pneumatic systems including bleed air and pressurization.
• Airframe Systems — Landing Gear Systems: Fixed and retractable gear, shock absorption (oleo-pneumatic struts), brakes, wheels, tires, anti-skid systems, and nosewheel steering.
• Airframe Systems — Aircraft Fuel Systems: Fuel tanks, pumps, valves, vents, fuel quantity indicating systems, fuel management, and fueling procedures.
• Airframe Systems — Environmental Systems: Cabin pressurization, air conditioning, heating, and oxygen systems — both crew and passenger.
• Airframe Systems — Aircraft Fire Protection Systems: Fire detection and extinguishing systems, smoke detection, and the maintenance of fire protection equipment.
• Airframe Systems — Ice and Rain Control Systems: Pneumatic de-icing boots, electro-thermal anti-icing, windshield ice protection, and rain removal systems.
• Airframe Systems — Flight Control Systems: Primary and secondary flight controls, actuation systems (cable, push-pull, hydraulic, fly-by-wire), trim systems, and control surface balancing.

The Airframe section requires both theoretical knowledge of how systems work and practical knowledge of how to inspect, troubleshoot, and maintain them. This is where hands-on experience from your apprenticeship or Part 147 training becomes invaluable.

4. Section AM.III: Powerplant

The Powerplant section of the ACS covers aircraft engines — both reciprocating (piston) and turbine (jet and turboprop). The Powerplant knowledge test (AMP) contains 100 questions. This section is essential for Powerplant-rated candidates, and the A&P combined certificate requires mastery of both AM.II and AM.III.

Subject areas in AM.III include:

• Reciprocating Engines: Four-stroke cycle theory, engine configurations (horizontally opposed, radial, inline), valve timing, ignition timing, and power output. Cylinder, piston, crankshaft, and valvetrain components.
• Turbine Engines: Gas turbine cycle (Brayton cycle), engine types (turbojet, turbofan, turboprop, turboshaft), compressor types (axial, centrifugal), combustion chambers, turbine sections, and exhaust systems. Thrust production and the factors affecting it.
• Engine Inspection: Reciprocating and turbine engine inspection procedures, compression testing, borescope inspection, and engine condition monitoring.
• Engine Instrument Systems: RPM (tachometer), oil pressure and temperature, cylinder head temperature, exhaust gas temperature, torque, fuel flow, and engine vibration monitoring. Normal operating ranges and exceedance handling.
• Engine Fire Protection Systems: Fire detection and extinguishing systems specific to the engine installation.
• Engine Electrical Systems: Starting systems, ignition systems (magnetos, igniters), electrical components, and wiring on the engine installation.
• Lubrication Systems: Wet sump and dry sump systems, oil types, filters, coolers, and oil analysis. Lubrication system troubleshooting.
• Ignition and Starting Systems: Magnetos, ignition harnesses, igniter plugs, timing procedures, and starter systems (electric, pneumatic, and turbine starters).
• Fuel Metering Systems: Carburetors, fuel injection systems, fuel control units, and the principles of fuel metering in both reciprocating and turbine engines.
• Engine Fuel Systems: Fuel types, fuel system components (pumps, filters, valves, fuel control units), and fuel system maintenance procedures.
• Induction Systems: Air induction, carburetor heat, alternate air, and the effects of induction icing.
• Engine Cooling Systems: Air-cooled design (fins, baffles, cowl flaps) and liquid-cooled systems. Cooling system maintenance and inspection.
• Engine Exhaust Systems: Exhaust manifolds, turbochargers, wastegates, and exhaust system inspection for leaks and cracks.
• Propellers: Fixed-pitch and constant-speed propellers, feathering and reversing, propeller governors, synchronization, and ice protection. Propeller tracking, balancing, and hub inspection.
• Powerplant Inspection: The scope of powerplant inspections, including Appendix D items specific to the engine installation.

The Powerplant section benefits greatly from the use of visual study aids and practical examples. Understanding the difference between a carbureted engine and a fuel-injected engine, or between a centrifugal compressor and an axial compressor, requires both memorization and conceptual understanding. The Sky License AI Tutor is particularly helpful here, as you can ask for plain-language explanations of complex thermodynamic and mechanical concepts.

5. Study Strategies for the ACS

Mastering the Aviation Mechanic ACS requires a structured approach. Here are proven strategies used by successful A&P candidates:

1. Map the ACS to Your Study Plan

Start by downloading the full ACS from the FAA website. For each subject area, list every task and rate your current knowledge level (None, Basic, Proficient, Expert). This creates a personalized study roadmap and highlights exactly where to focus your effort. Most candidates find they have 2–3 strong subject areas and several weaker ones — invest your time proportionally.

2. Use Active Recall with Practice Questions

Reading textbooks is passive. Active recall — testing yourself with practice questions — is proven to be dramatically more effective for long-term retention. This is where Sky License excels. With thousands of questions mapped to every ACS subject area, you can test yourself repeatedly until the knowledge sticks. The AI-powered adaptive difficulty ensures you are always challenged at the right level.

3. Study in Section-Specific Blocks

Rather than mixing sections in a single study session, focus on one section at a time. Each section of the ACS has its own logical structure and vocabulary. Studying them separately prevents confusion and helps you build deep knowledge in each area. Once you have mastered individual sections, take comprehensive practice exams that mix questions from AM.I, AM.II, and AM.III — exactly like the real Airframe and Powerplant tests do.

4. Leverage AI-Powered Study Tools

Modern AI tools can dramatically accelerate your exam preparation. Platforms like Sky License use adaptive algorithms that identify your weak areas and generate targeted practice questions. The AI Tutor feature lets you ask natural-language questions about complex topics — like "explain how a constant-speed propeller governor works" or "what is the difference between §43.7 and §43.9?" — and receive instant, exam-focused answers.

5. Simulate Exam Conditions

Practice under real exam conditions: timed, with no interruptions, in a quiet environment. The actual FAA knowledge tests are computer-based at PSI centers with a strict 2-hour limit per test. If you have only practiced in a relaxed, untimed setting, you may be shocked by the time pressure on exam day. Sky License's exam simulation mode replicates the exact format, timing, and difficulty of the real tests, so you walk in fully prepared.

6. Review and Iterate

After each practice session, review every question you got wrong. Understandwhy the correct answer is correct and why your choice was wrong. This is far more valuable than simply reading the correct answer. Use the detailed explanations in Sky License to trace your mistake back to the specific ACS task, then revisit that topic. Over time, your accuracy will improve as you close knowledge gaps systematically.

6. Frequently Asked Questions

Master the ACS with Sky License

The Aviation Mechanic ACS is your roadmap to A&P certification in the United States. By understanding its structure — three sections with specific subject areas and tasks — you can study with precision and confidence. Whether you are pursuing an Airframe rating, a Powerplant rating, or both, every minute spent mastering the ACS is an investment in your career as an aircraft maintenance professional.

Sky License was built specifically to help you navigate and master this syllabus. With thousands of practice questions, adaptive AI difficulty, real exam simulations, and an AI Tutor that explains any concept in plain language, you have everything you need to pass your exams on the first attempt.

Start Studying with Sky License →