FAA Mechanic ACS Codes

There are three FAA documents in an A&P candidate's life. The handbooks teach the material, the regulations set the rules, and the Airman Certification Standards define what is actually examined. Only one of those is written in the units your test report and your examiner both use, and it is this one.

Published as FAA-S-ACS-1, the ACS replaced the older Practical Test Standards and did something the PTS never did: it unified the written test and the oral and practical under a single standard. Before that, the knowledge test and the practical exam were separate documents covering overlapping ground. Now every question on a written test is tagged to an ACS element, and the examiner conducting your oral works from the same list.

That is why the codes on an Airman Knowledge Test Report are worth more than the percentage printed above them. Each one names a subject area you got wrong and that your Designated Mechanic Examiner is directed to revisit. It is simultaneously the most precise study list you will ever be handed and a preview of part of your oral exam.

Work by subject area, not by handbook chapter number and not by the whole bank. The area is the unit the FAA writes questions against, the unit your fail report names, and therefore the unit in which progress can actually be measured.

For each area you are weak on, the sequence that works is: read what the area covers, read the FAA handbook section it maps to, then drill that area's questions and track its score on its own. Reading the rationale on every miss — and on every lucky guess — is where the transferable knowledge is; the individual question is disposable. Above 85 percent on an area is the point at which it stops being a liability, because the 70 percent pass mark leaves no margin for an unfamiliar phrasing on the day.

Every area page below carries what the area covers, its FAA handbook references, the three traps candidates most often fall into, and free practice questions with worked rationales. Larger areas also have a full question browser with every published question in that area.

If you are here because you failed a written test, start at ACS-code remediation instead — paste the codes from your report and it will group them for you.

Section I, General, is examined on the 60-question General written test and is required for both ratings. Twelve areas across 60 questions makes it the densest of the three, and two of those areas — electricity and mathematics — are computational and carry a disproportionate share of the marks.

Section II, Airframe, is examined on the 100-question Airframe written test. Fifteen areas make it the broadest of the three, which is why its characteristic failure is thin coverage rather than one catastrophic gap.

Section III, Powerplant, is examined on the 100-question Powerplant written test. Thirteen areas, dominated by two large engine families, so its characteristic failure is asymmetry — fluent on pistons and hollow on turbines, or the reverse.

What is the FAA Mechanic ACS?

The Airman Certification Standards, published as FAA-S-ACS-1, is the single document that defines what an Aviation Mechanic applicant must know, understand and be able to do. It replaced the older Practical Test Standards and, crucially, now governs both the written knowledge tests and the oral and practical exam. That unification is what makes the codes on your test report actionable: the examiner is working from the same standard the test was written against.

How many ACS subject areas are there?

Forty across the three sections: twelve in Section I (General), fifteen in Section II (Airframe), and thirteen in Section III (Powerplant). Each area contains numbered Knowledge, Risk Management and Skill elements, and every question you meet on a written test is tagged to one of them.

How do I read a code like AM.II.F.K5?

Left to right: AM is Aviation Mechanic; the roman numeral is the test section, with I for General, II for Airframe and III for Powerplant; the letter is the subject area within that section, here F for Hydraulic and Pneumatic Systems; and K5 is the fifth Knowledge element in that area. R codes are Risk Management elements and S codes are Skill elements.

Why do ACS codes appear on my test report?

Your Airman Knowledge Test Report lists a code for every question you answered incorrectly, whether or not you passed. Those codes serve two purposes: they tell you precisely which subject areas to restudy, and they tell your Designated Mechanic Examiner which areas to revisit during the oral and practical exam.

Which FAA handbook covers each ACS area?

General areas map to FAA-H-8083-30B, Airframe areas to FAA-H-8083-31B, and Powerplant areas to FAA-H-8083-32B. Each area page below names the specific handbook reference the FAA associates with that area, so you can go from a code on a report to the right chapter in one step. All three handbooks are public domain and free from faa.gov.

Are the practice questions on these pages free?

Yes. Every question shown on the area pages and in the per-area question browsers is free to read, with the correct answer, a worked rationale and its FAA handbook reference, and no account is needed. What a subscription adds is the engine around them: adaptive question selection, per-area mastery tracking, the timed exam simulator, saved remediation plans and the oral simulator.

• FAA Airman Certification Standards — Aviation Mechanic (FAA-S-ACS-1)
• FAA Aviation Maintenance Technician Handbooks (FAA-H-8083-30/31/32)
• 14 CFR Part 65, Subpart D — Mechanics