What Is MEI Certification?

What the Multiengine Flight Instructor Rating Actually Is

The Multiengine Flight Instructor Rating, commonly shortened to MEI, is an FAA rating that authorizes a certificated flight instructor to teach in multiengine airplanes. It is not a standalone certificate. It is an add-on to an existing flight instructor certificate with an airplane category rating, and it is earned by demonstrating instructional competence in a multiengine airplane to an FAA inspector or designated pilot examiner.

If you have landed on this page while searching for the meaning of the acronym, the short version is this: in aviation, MEI means a pilot who is qualified to instruct in airplanes with more than one engine. If you want a quick orientation on the terminology itself, our short explainers on what MEI is and what MEI stands for cover the vocabulary, while this article goes deeper into how the rating works and what the evaluation covers.

The rating matters because multiengine training demands a different kind of teaching. Instructors must be able to explain and demonstrate asymmetric flight, engine-out procedures, and performance limits that single-engine instructors never face in routine training. The evaluation exists to confirm that you can do this safely and clearly, not merely that you can fly the airplane well yourself.

Who Sets the Standard: FAA and the Flight Instructor ACS

The governing body is the Federal Aviation Administration. The standard it uses is the Flight Instructor Airplane Airman Certification Standards, published as FAA-S-ACS-25. This edition is dated November 2023 and became effective May 31, 2024. It replaced the older Practical Test Standards approach with the ACS framework, which ties every Task to the knowledge, risk management, and skill elements an applicant must demonstrate.

That structure shapes how you should think about preparation. The ACS is not a question bank and it does not assign percentage weights to its content. It is a list of Areas, each containing Tasks, and each Task is broken into Knowledge, Risk Management, and Skill elements. Your evaluator builds the test from those Tasks, so your study plan should mirror them. For a wider look at how each content area breaks down, see our complete guide to all 14 content areas.

The 14 ACS Areas, Explained for Multiengine Candidates

The Flight Instructor Airplane ACS lists 14 overarching Areas. They are headings that organize Tasks, not percentage-weighted exam domains, and the practical test does not draw equally from each one. Importantly, you should not assume all 14 are required for every multiengine add-on applicant. Which Tasks you must be evaluated on depends on the ratings you already hold, which is covered in the next section.

Here is how each Area looks through a multiengine instructor's lens.

The Additional Rating Table and the Least Restrictive Rule

This is the part of the ACS that candidates most often misread. The standard includes an additional multiengine instructor rating table, located on printed page 98 of the document. It determines which Tasks you are required to be evaluated on, and the answer depends on the ratings you already hold.

Two rules govern how to use it:

1. Your existing ratings determine the required Tasks. Someone who already holds an instructor rating in another airplane class is not starting from zero, and the table reflects that.
2. If multiple held ratings produce different requirements, the least restrictive applies. In other words, you are held to the lighter of the applicable requirements, not the heavier.

Before your checkride, sit down with the table and your logbook and identify exactly which ratings you hold. Then confirm with your evaluator in advance which Tasks they expect to cover. Our MEI requirements guide walks through eligibility and prerequisites that come before this step.

Knowledge Testing: AFA, FIA, and What Applies to You

Knowledge testing for instructor ratings is where assumptions cause the most trouble, so precision helps here. The FAA's current testing matrix, revised September 25, 2026, distinguishes between two instructor knowledge tests relevant to airplane instructors:

Several caveats come with those figures:

• Optional unscored validation questions are excluded from the listed counts but are included in testing time. Do not be alarmed if your test feels slightly longer than the headline number suggests.
• Glider-rated instructors adding airplane use the FIA. Added-rating tests are not for holders of a sport-only instructor certificate.
• 14 CFR 61.191(b) provides an exemption related to the fundamentals-of-instructing test. It is not a blanket exemption from every knowledge test, and you should not read it as one.
• The AFA is not a universal MEI knowledge test. Whether you need any knowledge test at all for your particular multiengine add-on depends on your certificates and ratings, so verify with your evaluator or flight school before you register.

Because applicability varies, treat the testing matrix as the authority and confirm your path before paying for anything. For what the numbers mean for scoring, see the MEI passing score guide, and for scheduling logistics see testing windows and scheduling.

Multiengine Topics You Must Master

Because the ACS organizes content by Area, multiengine material is spread across several of them, concentrated in Emergency Operations and Multiengine Operations. The following topics are the ones an instructor candidate should be able to both fly and explain to a student.

Candidates who treat these as flying skills only tend to struggle, because the evaluator is judging the explanation as much as the maneuver. For a deeper treatment of the knowledge side of preparation, see our MEI study guide and the condensed one-page review.

What the Practical Test Looks Like

The Multiengine Flight Instructor Rating is earned through a practical test conducted by an FAA inspector or designated pilot examiner. It combines oral questioning and flight, and the ACS Task structure determines the content of both.

• Oral portion: Expect to teach. The evaluator may play the role of a student, asking questions, making errors, or misunderstanding a concept, and you are judged on how you respond.
• Preflight lesson: You will typically be asked to deliver a lesson on a maneuver to be performed in flight, which tests your ability to organize and communicate a lesson plan.
• Flight portion: You will demonstrate maneuvers and procedures from the multiengine airplane, including engine-out work, while explaining what you are doing.
• Error analysis: The evaluator may fly a maneuver incorrectly on purpose, and you must identify and correct the errors.

The evaluator builds a plan of action from the ACS and from the table discussed earlier, so the exact Tasks vary between candidates. Because of that variability, be wary of any claim about what "the" test contains. To gauge how demanding this evaluation tends to feel, our difficulty guide covers where candidates typically struggle, and our pass rate article explains what the available data does and does not show.

Who Hires Multiengine Instructors

A multiengine instructor rating opens a specific set of doors. The people and organizations that value it are those that train pilots toward multiengine privileges.

• Part 61 and Part 141 flight schools that operate a twin and need instructors for multiengine add-ons, commercial multiengine training, and instrument work in the twin.
• University and collegiate aviation programs whose professional pilot tracks include multiengine training in their curriculum.
• Regional and career-track pilot academies that prepare students for airline-bound hiring pipelines, where multiengine time and experience are commonly valued.
• Corporate and private owners of light twins who hire instructors for proficiency training, transition training, and recurrent work.
• Independent instructors who build a niche teaching in customers' own airplanes.

The practical advantage is that multiengine instruction is a narrower market than primary instruction, which can mean greater scheduling value per airplane and per instructor, depending on the local market. We deliberately avoid quoting income figures here, since they vary widely by region and employer. If you want a fuller look at the economics, see our earnings analysis, the cost breakdown, and the ROI analysis. For openings and role types, see our page on MEI jobs.

Sequencing Your Preparation Around the ACS

Rather than a generic study calendar, sequence your preparation so that the Areas that depend on each other are built in order. This is one reasonable ordering, built around how the Areas connect to the multiengine rating.

The logic of this order is simple: teaching fundamentals first, then the multiengine material you will be teaching, then the maneuvers, then integration. If you want unlimited timed questions to test your knowledge as you go, the MEI Exam Prep practice tests are built for that kind of repetition.

Frequently Asked Questions

The Multiengine Flight Instructor Rating rewards candidates who understand both the airplane and the art of teaching in it. Read the ACS itself, confirm your testing path with the FAA's current matrix, and build your preparation around teaching the multiengine material clearly, not just flying it well.