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.

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

Failing one of the three FAA A&P knowledge tests is more common than many candidates expect — and it is entirely recoverable. The Airman Knowledge Test Report (AKTR) you receive after a failed test is not just a score document; it is a precise diagnostic tool that identifies exactly which subject-area knowledge codes (ACS codes) you missed. Used correctly, the AKTR gives you a targeted remediation plan that makes the retake more efficient than your original preparation. This guide walks you through the retest rules, how to read your AKTR, and how to turn ACS codes into a focused study plan.

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.

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.

Primary sources

Related guides

Start your A&P exam prep today

Adaptive practice, ACS-code remediation, and oral prep — everything you need to pass.

Start free See plans