Share to any workspace or social platform
66.A.25 specifies the basic knowledge standards and examination requirements that applicants must satisfy for each licence category, covering subjects such as mathematics, physics, electrical fundamentals, and aircraft-specific technology modules.
What it means in practice
Before you can obtain a Part 66 licence, you must pass examinations covering a range of technical subjects defined in Appendix I to Part 66. The subjects are organised into numbered modules, from Module 1 (Mathematics) through to Module 17 (Propeller), with different modules required depending on the licence category. For example, a Category B1.1 applicant must pass modules covering turbine engine technology, while a Category A applicant faces a reduced syllabus with less depth.
The knowledge level required varies by category. Category A examinations test knowledge at a lower level than Category B1 or B2. Each module has defined knowledge levels (Level 1, 2, or 3) that specify how deeply the applicant must understand each topic. Examinations can be taken at a Part 147 approved training organisation or directly with the competent authority.
Key requirements
Examinations must be conducted under controlled conditions, with multi-choice questions forming the standard format. The pass mark is 75%. Examination results are valid for 10 years from the date of the examination, meaning if you do not apply for your licence within that period, you may need to re-sit expired modules.
Applicants who complete an approved basic training course at a Part 147 organisation benefit from the course being designed to meet the full syllabus requirements. Those taking the direct examination route with the competent authority must ensure they have studied the complete Appendix I syllabus for their category. Credit may be given for previous qualifications or training, subject to competent authority assessment.
Common compliance gaps
A frequent issue is applicants not realising that examination passes expire after 10 years. If there is a long gap between passing examinations and submitting a licence application, some module passes may have lapsed. Another common problem is applicants studying the syllabus for the wrong category level, particularly when upgrading from Category A to Category B1, where additional modules and higher knowledge levels are required.
Part 66 Training
Working towards your Part 66 licence?
Sofema's Part 66 Foundation course walks you through the full licensing framework — categories, modules, experience requirements, and the path to certification.
View Part 66 courseSources
Have a question about this regulation?
Search across all regulation pages and glossary terms.