Retaking the FAA A&P Written Test — AKTR, ACS Codes, and Remediation

The 30-Day Wait and the Instructor Endorsement Alternative

Under FAA regulations, if you fail a knowledge test you must wait a minimum of 30 calendar days before retaking that test — the clock starts on the day you took the failed test. There is one alternative: if you receive a ground instructor endorsement from a certificated ground instructor (or an appropriately rated mechanic instructor) attesting that you have received additional ground training on the subject areas you failed, you may retest before the 30-day period expires. In practice, most candidates simply use the 30 days to review their weak areas — the timeline is short enough that the waiting period is rarely a hardship. There is no limit on the number of times you may retake a failed test. Each retest requires the standard test fee.

Understanding Your AKTR: The Fail Report

The Airman Knowledge Test Report (AKTR) is issued by PSI immediately after your test, whether you pass or fail. A passing AKTR is your authorization to present to a DME. A failing AKTR is your remediation roadmap. The AKTR shows: your overall score (as a percentage), the number of questions answered correctly and incorrectly, and — critically — the ACS codes of the knowledge areas where you missed questions. These ACS codes are the most actionable information on the document. Keep every AKTR (passing and failing) — you will need all passing AKTRs when you sit your O&P with a DME, and the FAA may request records of failed tests in certain enforcement contexts.

Reading the ACS Codes on Your AKTR

Each ACS code on your failing AKTR corresponds to a specific knowledge item in the Mechanic ACS. The code format (e.g., AM.I.A.K1 for General section, subject area A, knowledge item 1) tells you exactly which section, area, and subject you missed. Look up each code in the ACS document (FAA-S-ACS-1): the ACS entry tells you the knowledge item description and the primary reference material (usually a specific AMT handbook chapter or a 14 CFR section). This cross-reference is the key: instead of re-studying the entire handbook, go directly to the chapters cited for your missed ACS codes. AMTprep's ACS-code remediation feature is designed specifically for this workflow — enter your missed codes and the platform serves targeted practice questions on exactly those areas.

Building a Targeted Remediation Plan

Effective remediation after a failed test focuses on the specific ACS codes you missed, not on re-reading material you already know. Step 1: List every ACS code from your failing AKTR. Step 2: Look each code up in the ACS and note the referenced handbook chapter or regulation. Step 3: Read those specific sections of the AMT handbooks and regulations, not the entire document. Step 4: Practice questions filtered to those ACS codes — not a general mixed-topic practice session. Step 5: After 2–3 focused study sessions, assess your confidence on each code; continue drilling codes where you still feel uncertain. Step 6: Retest after the 30-day window, or earlier if you obtain an instructor endorsement. This targeted approach typically produces higher retake scores than a broad re-study of the entire subject area.

Common Reasons Candidates Fail a Knowledge Test

The most frequently failed ACS areas include: 14 CFR Part 43 maintenance documentation requirements (particularly the content and signature requirements for maintenance entries and return-to-service statements); weight and balance calculations (requires arithmetic under time pressure); electrical circuit analysis and Ohm's law applications; NDT method selection and procedure steps; and turbine engine theory and performance parameters. Candidates who fail the Airframe or Powerplant tests often do so because they underinvested in the General subject areas that carry over into those tests. If your AKTR shows missed codes concentrated in one subject area, that area is likely both undertrained and heavily weighted — prioritize it.

The Link Between Your AKTR and the Oral and Practical Exam

Your DME will review all of your AKTRs — passing and failing — before the O&P exam. A history of failed tests is not disqualifying, but the DME may probe the subject areas where you struggled on the written tests during the oral portion of the exam. This means your AKTR remediation work doubles as O&P preparation: the ACS codes you missed on the written test are likely areas the DME will explore during the oral. Thorough remediation before the retake produces better written-test scores and a more confident O&P performance.

What the Instructor Endorsement Actually Requires

The exception in 14 CFR 65.19 that lets you retest inside 30 days is narrower than it first appears, and it is worth reading precisely before planning around it.

The statement must come from an airman who holds the certificate and rating you are seeking. For an A&P applicant that means a certificated mechanic with the relevant rating — not any instructor, not a colleague without the rating, and not a commercial prep course as an institution.

It must certify two distinct things. That the airman has given you additional instruction in each of the subjects you failed, and that they consider you ready for retesting. The word each is doing work: instruction in one weak area does not cover a report listing five.

And it is a real endorsement. Someone is attaching their certificate to a statement that they taught you and that you are ready. A mechanic asked to sign it without having done the instruction is being asked to falsify a record, which is why the sensible way to use this provision is to arrange the instruction first and ask for the statement afterwards.

In practice, most candidates are better served by the 30 days. If the material genuinely was not there on test day, four weeks of structured work is closer to what it takes than a signature is.

A Four-Week Remediation Schedule

Thirty days is enough to fix a written-test failure if the time is structured. Here is a schedule that works.

Week one is diagnosis and reading. Group the ACS codes on your report by subject area and count them; the clusters, not the individual codes, are your real problems. For each cluster, read the corresponding handbook chapter before touching a practice question. Resist the urge to start drilling — the failure has already demonstrated that answering questions without the underlying material does not work.

Week two is targeted drilling. One area per session, practising only that area, tracking its score separately. Read the rationale on every miss and on every lucky guess. Return to the handbook whenever a rationale references something unfamiliar. Expect the first sessions in a weak area to be uncomfortable; that is the point.

Week three broadens. Keep working the weak areas but reintroduce the areas you passed, because four weeks of ignoring them is long enough for decay. Build your numbers page and your symptoms page if you have not already, and review both daily.

Week four is full-length timed runs under real conditions, twice or three times, with the gaps they expose fed back into short targeted sessions. No new material in the final week.

When to Book the Retest

The eligibility date and the readiness date are different dates, and the mistake that produces a second failure is treating them as the same one.

The criterion to book on is a practice score, not a calendar. Consistently above 85 percent on full-length runs, and above 85 percent on each of the areas your report flagged, taken separately. The pass mark is 70, and the gap between 70 and 85 is the margin that absorbs an unfamiliar phrasing, a bad night, and the two or three questions on every form that are simply harder than the rest. A candidate practising at 72 percent is not ready; they are exactly at the line with nothing in hand.

Watch the 24-month clock while you wait. If you have already passed other written tests, those results expire two years from their own report dates, and the oral and practical has to happen inside that window. A long remediation on one test can quietly erode the time available for the rest of the sequence.

One more thing worth doing before you book: rehearse the flagged areas out loud. Every code on that report is also an item your Designated Mechanic Examiner is directed to revisit, so the work you are doing now is doing double duty.

Frequently asked questions

How long do I have to wait before retaking a failed A&P knowledge test?

You must wait a minimum of 30 calendar days from the date of the failed test. The one exception is if you obtain a written endorsement from a certificated ground instructor (or appropriately rated aviation mechanic instructor) certifying that you have received additional instruction in the failed areas — with that endorsement, you may retest before the 30 days are up. Each retest requires paying the test fee again.

Does a failing AKTR expire?

A failing AKTR has no expiration — the retest window is open indefinitely. Only a passing AKTR expires (24 months from the pass date). Keep all failing AKTRs as part of your test history. There is no regulatory consequence to having failed one or more knowledge tests, provided you eventually pass all three before your O&P.

What if I fail the same test multiple times?

There is no limit on the number of retakes for a failed knowledge test. The 30-day wait (or endorsement alternative) applies each time. Focus each retake preparation cycle on your AKTR codes — if the same codes keep appearing, the underlying handbook chapters require deeper study. Consider studying with a ground instructor or mechanic mentor who can explain the difficult concepts in person.

I passed two tests but failed the third. Does the 24-month clock on my passing tests still run?

Yes. The 24-month validity period on each passing AKTR runs from that test's pass date, regardless of how many times you retake a failed test. If your General AKTR is about to expire while you are still retaking the Powerplant test, you must retake and re-pass General before it expires — otherwise you cannot complete your O&P. Plan your test schedule to avoid this situation.

Can I use the ACS codes on my AKTR to prepare for the DME oral exam?

Absolutely — and you should. The ACS codes from your failing AKTR are a map of your knowledge gaps. Your DME will see these same failed tests and may deliberately probe those areas during the oral portion. Thorough ACS-code remediation before your retake is also thorough O&P oral preparation.

How many times can I retake an FAA knowledge test?

There is no limit on the number of attempts. Each one requires either the 30-day wait or the 65.19 instructor statement, and each one is charged at the full test fee. There is no penalty carried forward and a previous failure does not appear on your certificate, but repeated attempts do consume both money and the 24-month window on any tests you have already passed.

Does a failed test show up anywhere permanent?

No. A failed knowledge test does not appear on your mechanic certificate and is not part of your permanent airman record in the way that some enforcement actions are. What does carry forward, and what matters, is the Airman Knowledge Test Report itself: when you eventually pass, it is the report from the successful attempt that you present, and its ACS codes are what your examiner works from at the oral.

ACS subject areas covered here

These are the FAA Mechanic ACS areas this guide maps to. Each page breaks the area down and carries free practice questions with worked rationales.

• Fundamentals of Electricity and Electronics (AM.I.A)
• Weight and Balance (AM.I.C)
• Regulations, Maintenance Forms, Records, and Publications (AM.I.I)
• Metallic Structures (AM.II.A)
• Reciprocating Engines (AM.III.A)

Primary sources

• FAA Aviation Mechanic Airman Certification Standards FAA-S-ACS-1 (PDF)
• 14 CFR §65.75 — Knowledge Requirements (eCFR)
• PSI Aviation Testing — Schedule an FAA Knowledge Test

Related guides

• FAA Mechanic ACS Explained — What Is the Airman Certification Standards?
• FAA A&P Written Tests Explained — General, Airframe & Powerplant