Part-66 Experience Logbook: How to Document OJT

Why Your Experience Documentation Matters

Part-66 requires all licence applicants to demonstrate their practical experience before a licence can be issued (66.A.30). This experience is documented in a personal logbook, with entries countersigned by the certifying staff who supervised the work. Without properly maintained documentation and valid countersignatures, your national aviation authority cannot verify your experience — regardless of how many years you have worked in the industry.

The logbook is not just an administrative formality. It is also a tool that helps you track your own progress, identify gaps in your experience, and ensure that you are getting exposure to all the subject areas relevant to your licence category. Many applicants discover partway through their 5-year experience period that they have been neglecting certain areas, forcing them to seek out additional work before their application is accepted.

Experience Requirements: 2 to 5 Years of Practical Work

The experience requirement for a Part-66 licence is defined in 66.A.30. You need 2 years for category A, 4 years for B1.2 (aeroplane piston), 5 years for B1.1, B1.3 and B2, and 2 years for B3. However, recognised training reduces these periods: 3 years instead of 5 for most B categories with a recognised technical diploma, 3 years instead of 4 for B1.2 with recognised training, and 2 years for holders of a recognised technician licence.

Your experience must be gained working with the procedures, practices, materials, tools, and equipment generally used in maintaining aircraft and components, and it must be supervised by certifying staff who can attest to the work you performed — which is why keeping contemporaneous, countersigned records is essential.

What You Need to Document

Your experience documentation should cover the full scope of work relevant to the licence category you seek. For a B1.1 or B1.2 licence, the main task areas include:

• Airframe Structures — Sheet metal repair, composite repairs, structural inspection, corrosion control, and major/minor repairs per the appropriate data (SRM, manufacturer's manuals, EASA approved data).
• Airframe Systems — Landing gear, flight controls, hydraulic and pneumatic systems, environmental control systems, fuel systems, fire protection, and ice and rain control.
• Powerplant Systems — Engine removal and installation, component replacement, troubleshooting, run-up and test procedures, and propeller maintenance.
• Engine Systems — Lubrication, ignition and starting, fuel metering, induction, cooling, and exhaust systems for piston and turbine engines.
• Electrical Systems — Wiring repair, component testing, battery maintenance, and system troubleshooting.
• Avionics Systems — Navigation and communication equipment, instrument systems, and autopilot testing (often performed alongside a B2-certified engineer).
• Maintenance Documentation — Work orders, maintenance record entries, and understanding the release to service (CRS) process.

For each task you log, include the date, aircraft type and registration, component part number and serial number (where applicable), a detailed description of the work performed, the reference data used (AMM chapter, SRM, AD, SB), and the name and licence number of the supervising certifying staff member.

How Much Detail Do You Need?

EASA does not specify an exact number of tasks or hours — the requirement is stated in years of experience, and your logbook entries demonstrate the breadth and depth of that experience. However, your documentation should demonstrate "sufficient variety and depth" across the task areas for your category. Most successful applicants log between 150 and 400 individual tasks across their experience period, spanning multiple aircraft types and systems.

A common mistake is logging the same type of task repeatedly — for example, 100 tyre changes — without getting exposure to other areas like structural repairs or systems troubleshooting. The authority and your assessor look for breadth as much as depth. If your documentation shows that you have only worked on one type of aircraft or one type of task, you may be asked to get additional experience before your licence is issued.

Documentation Formats: Paper vs Digital

EASA accepts both paper and digital experience logs, as long as they contain the required information and can be verified by the certifying staff who countersigned them. Paper logbooks are traditional and still widely used, but digital tools offer significant advantages: automatic backups, easier searching, the ability to generate summaries for your licence application, and built-in reminders.

Whichever format you choose, ensure that your entries are made promptly — ideally at the end of each shift or within a few days of completing the work. Entries that are logged weeks or months after the fact are harder to verify and may raise questions during the licence review. Each entry should be reviewed regularly by your supervising engineer so they can confidently countersign your experience when you apply.

The Logbook and Licence Application Process

When you have completed your experience requirements and passed your module exams, you prepare your licence application. The steps are:

• Complete your logbook — Ensure every entry is dated, described, referenced, and countersigned by the certifying staff who supervised the work.
• Gather your module certificates — Collect the passing reports for every module in your category's syllabus (66.A.25).
• Submit your application to the national aviation authority — Along with your logbook, module certificates, proof of training (if applicable), and identification.
• Pass the assessment of competence — B1 and B2 candidates complete the practical assessment (66.A.40), after which the authority issues the licence.

If the authority finds issues — missing countersignatures, insufficient variety, or unverifiable experience — they will tell you what needs to be corrected. Addressing these deficiencies can take anywhere from a few weeks to several months, depending on the nature of the issue. This is why keeping your documentation organised from day one is so important.

Common Documentation Mistakes to Avoid

Based on feedback from national authorities, examiners, and experienced certifying staff, here are the most common documentation errors that cause certification delays:

• Missing supervisor details — Every entry should note the supervising certifying engineer's name and licence number. A log full of unsupervised "I did X" entries is hard to verify credibly.
• Vague task descriptions — "Performed maintenance on Airbus A320" is not sufficient. Describe exactly what you did: "Removed and replaced No. 2 engine oil filter, performed leak check, and completed ground run per AMM Chapter 79."
• No data references — Include the applicable data for each task (AMM chapter, SRM, AD number, or manufacturer's instructions). This mirrors what EASA expects of maintenance records under Part-145.
• Too much repetition — 100 similar wheel changes do not demonstrate breadth. Seek out diverse tasks early in your experience period.
• Illegible entries (paper logbooks) — If your supervisor or the authority cannot read it, it does not count. Consider a digital log if your handwriting is difficult to read.
• Backdating entries — This is a serious offence that can result in your application being rejected outright. Always log entries promptly and accurately.

Tips for a Smooth Certification

Here are practical strategies that will help you avoid delays when your experience is reviewed:

• Start organised. Set up your documentation format on day one. Use consistent naming conventions, task categories, and reference formats throughout.
• Review quarterly. Every three months, go through your log and identify any task areas that you are neglecting. Use this review to guide conversations with your supervisor about the types of work you need.
• Get your supervisor involved early. Make sure the certifying engineers you work with understand that you will need countersigned experience, and ask them to review your entries regularly. Some supervisors prefer to review weekly rather than letting entries pile up.
• Keep supporting documents. Retain copies of work orders, job cards, and maintenance records that correspond to your log entries. While you do not need to submit these with your application, having them available can resolve questions quickly.
• Use a digital log tool. Digital platforms often include structured fields that prevent the common mistakes listed above, and they make it easy to generate the summary your supervisor needs to verify your experience.

Preparing for Your Module Exams While Logging Hours

One of the best things you can do as an apprentice is to study for your Part-66 module exams while you are logging your practical experience. The material in the modules — especially the aircraft structures, systems, and propulsion subjects — directly relates to the work you are doing every day. Studying and working simultaneously reinforces both your theoretical knowledge and your practical skills.

Skylicence Europe is designed to fit around your apprenticeship schedule. Our platform's adaptive learning algorithms identify your weak areas and focus your study time where it is most needed, so you can prepare for exams efficiently without sacrificing time on the hangar floor. Many of our users pass all their module exams before completing their experience requirement, allowing them to move directly to the assessment of competence as soon as their experience is complete.

Read the full Part-66 Apprentice Guide: how to become an Aircraft Maintenance Engineer →

See the complete step-by-step path to your Part-66 licence →