The A&P ACS codes applicants miss most, from FAA data
Updated October 25, 2026 · from the FAA's Frequently Missed Knowledge Test ACS Codes reports
The FAA publishes a list of knowledge test ACS codes that applicants frequently miss. In the latest report, three of them come from the A&P mechanic writtens. The same three codes appear in all five reports on the FAA's test statistics page, covering July 2023 through June 2025.
Practice all three out loud, free
The three codes in the latest report
2nd Quarter, CY25 report, July 1, 2024 – June 30, 2025.
| ACS code | ACS element | Missed |
|---|---|---|
| AM.II.D.K5 AMA, Airframe written | Airframe Inspection: Special inspections | 79.53% |
| AM.I.G.K6 AMG, General written | Cleaning and Corrosion Control: Corrosion identification and inspection | 78.49% |
| AM.I.A.K24 AMG, General written | Fundamentals of Electricity and Electronics: Electrostatic discharge | 74.91% |
Every report so far
| Report | AM.II.D.K5 | AM.I.G.K6 | AM.I.A.K24 |
|---|---|---|---|
| Q2 CY25 Jul 2024 – Jun 2025 | 79.53% | 78.49% | 74.91% |
| Q1 CY25 Apr 2024 – Mar 2025 | 78.75% | 77.45% | 73.88% |
| Q4 CY24 Jan – Dec 2024 | 79.83% | 77.12% | 74.25% |
| Q3 CY24 Oct 2023 – Sep 2024 | 80.4% | 77.29% | 74.5% |
| Q2 CY24 Jul 2023 – Jun 2024 | 81.73% | 77.32% | 74.51% |
What the numbers mean
The FAA labels the figure "Percent Missed" and gives it for each ACS code, so it describes the questions coded to that element. It is not the share of applicants who failed a written test. The reports list the codes but do not publish how they are selected, so read them as a signal of hard topics, not as a ranking of every topic or a prediction of your test.
Why this matters for the oral
Each of the ACS codes on your Airman Knowledge Test Report (AKTR) adds one question to that oral section, on top of a minimum of four random questions (FAA Mechanic Test Generator FAQ). If one of these three codes is on your report, expect the examiner to ask about it. Even if it is not, these are topics many applicants find hard, so they are worth explaining out loud before test day. More: how ACS codes turn into oral questions.
Practice each one
One sample oral question per code, from DMEReady's practice set built from public FAA sources. These are not FAA test questions.
AM.II.D.K5 · Airframe Inspection
Special inspections
“After a hard or overweight landing, what does the special structural inspection cover?”
Study source: AC 43.13-1B, chapter 9, page 9-9
Answer it out loud, freeAM.I.G.K6 · Cleaning and Corrosion Control
Corrosion identification and inspection
“Walk me through the methods you would use to inspect an aircraft for corrosion.”
Study source: FAA-H-8083-30B (Aviation Maintenance Technician Handbook, General), chapter 8, page 8-11
Answer it out loud, freeAM.I.A.K24 · Fundamentals of Electricity and Electronics
Electrostatic discharge
“What are the ESD hazards and the handling precautions for solid-state components?”
Study source: FAA-H-8083-30B (Aviation Maintenance Technician Handbook, General), chapter 12, pages 12-4, 12-5, 12-6
Answer it out loud, freeStill studying for the written? Try explaining today's topic out loud. Look up any other code on the A&P ACS codes page. DMEReady is an independent study tool, not affiliated with or endorsed by the FAA.