EASA Part-66 Module 3: Electrical Fundamentals

Electricity from first principles, in twenty topics, and the first three rows are about charge and about words rather than circuits. Topic 3.1, electron theory, opens at level 1 with the structure of the atom and what makes one material a conductor and another an insulator. Static electricity and conduction follows at level 2, and it’s more practical than the name suggests: an aeroplane collects charge in flight and sheds it through the static wicks on its trailing edges, and a bowser gets bonded to the airframe before a fuel cap comes off. Electrical terminology at 3.3 then settles what the words mean, potential difference, electromotive force, current and resistance, before the systems papers start using them without introduction.

The DC half does most of the arithmetic. Generation of electricity sits at 3.4 and its sources at 3.5, which in practice means the battery, the ground power unit and the bus everything arrives on, while DC circuits at 3.6 is where Ohm’s law and Kirchhoff’s voltage and current laws begin earning their place. The circuit on an aeroplane isn’t the circuit in the textbook, though. Most metal aeroplanes are wired with a single conductor and use the airframe itself as the return path, which is why a corroded earth stud shows up as a dim landing light rather than a dead one, and why the return is worth checking before you condemn a component.

Resistance and power take the next three rows, and they’re the practical heart of the DC material. Topic 3.7(a) is resistance itself, which EASA’s guidance opens out into specific resistance, series and parallel combinations, potentiometers and rheostats, and the Wheatstone bridge. Topic 3.7(b) covers the resistors as components, their colour code, tolerances, construction and temperature coefficients, and sits at level 1, while power at 3.8 turns all of it into heat and watts, which is where cable sizing and breaker ratings come from. Capacitance at 3.9 brings in the first component that stores energy in a field instead of losing it as heat.

At topic 3.13 the module changes gear, and the quantities stop sitting still. AC theory is followed by resistive, capacitive and inductive circuits at 3.14, transformers at 3.15, filters at 3.16, and AC generators and AC motors at 3.17 and 3.18. A large aeroplane makes most of its power as alternating current at 400 Hz rather than at the frequency of a domestic socket, and it does that for weight: the faster the field alternates, the smaller a transformer or a motor can be. Reactance is the idea to get straight here, because once current and voltage stop being in step, an intuition built on DC gives confident wrong answers.

None of this gets taught as aeroplane systems, and that’s deliberate: Module 3 stops at the machine on the bench and the circuit on the page. The installed article, with a bus bar behind it and a control unit deciding when it comes on line, is electrical power at topic 11.6, where EASA asks B1.1 for level 3, as the UK CAA does, and that paper assumes this one and never repeats it.

EASA allows 65 minutes for 52 questions, three answers to each and no essay, and there isn’t a single dash, the table’s mark for a topic not required, in Module 3’s B1 column, so nothing in the module is excused for this category. The AMC EASA publishes beside the regulation then gives every one of the twenty topics at least one question, the four rows it keeps at level 1 included, from one on filters and on magnetomotive force up to 4 on capacitance and 4 on inductance. So this is one of the few syllabuses in the set you can read straight through as a list of things you’ll be asked about, with no part of it set aside for somebody else’s licence. EASA’s guidance calls those counts acceptable rather than binding, so a setter may use a different spread where the deviation is justified, and only the total of 52 is fixed.

The 75% pass mark lands on 39 correct answers here, leaving 13 in hand, and that allowance doesn’t travel: each of the thirteen papers carries its own 75%, with no aggregate across the set and no averaging of a poor afternoon against a good one. A comfortable Module 1 or Module 2 counts for nothing on the day you sit this one, and a difficult Module 3 takes nothing back from the modules you’ve already banked. Every result stands as its own verdict.

Nothing in the EASA column for Module 3 reaches level 3, each EASA row carries the number of questions EASA’s guidance gives it, and the UK CAA column matches the levels row for row: the same twenty codes, in the same order, at the same depth. Only 3.5 carries a UK title under the EASA one, and what differs there is word order rather than depth. Read the level column before the titles. It’s almost flat, and a flat column means the real question is which rows you haven’t met yet, never which of them goes deepest.

Hardly at all, and this is one of the cleanest agreements in the whole set. The UK CAA’s paper matches EASA’s, 52 questions against a 65 minute clock and no essay, and the UK CAA numbers it plain Module 3, with no letter suffix, which deserves a second look on a UK table that still carries 7A, 9A, 11A and 17A from the text Great Britain froze at the end of 2020. Judge it by the codes and the two tables are a single table: 3.1 through to 3.18 in an unbroken sequence, with nothing numbered by either authority that the other numbers differently, no code carrying two different subjects, and the same level against every row. Module 3 is one of the nine papers the UK CAA sets to EASA’s count, and few in that group keep the syllabus this still: Modules 2, 5, 7, 11 and 15 match on the count and part company somewhere underneath it.

The only differences anywhere in the table are in the wording, and they all sit in the DC half. At 3.5, EASA writes “Sources of DC electricity” and the UK “DC Sources of Electricity”, the same four words in a different order and nothing more. Under 3.7, EASA’s two rows read simply “Resistance” and “Resistors”, while the UK gives neither part a title of its own: its (a) part opens “Resistance and affecting factors” and its (b) part runs from positive and negative temperature coefficients through the way fixed and variable resistors are built to potentiometers, rheostats and the Wheatstone bridge.

A title in Appendix I is a heading rather than the syllabus itself. Since EASA’s 2023 rewrite the regulation’s table carries headings only and the detail under each sits in EASA’s guidance; set against that guidance, what the UK prints under 3.7 names material EASA lists too. “Affecting factors” turns a noun into a job: go and find out what changes a conductor’s resistance. EASA covers the same ground with specific resistance at 3.7(a) and the factors behind each electrical term at 3.3. The UK’s (b) part puts how a resistor is built, and how it drifts as it warms up, in the row itself, and EASA’s guidance lists both under its bare “Resistors”. So what differs is where the detail is printed, not what either paper can ask.

The wider split between the two authorities is on the EASA versus UK CAA page: mutual recognition, which licence to go for, and what happened to the conversion route.

This page covers one of the 13 papers. The rest of the guide covers the route they sit inside: what the exam is, what else you must have done besides passing it, and how the two authorities differ.

EASA requires thirteen modules for category B1.1, and the UK CAA examines the same thirteen subjects. The UK CAA syllabus differs in nine of them, and the UK still adds an A to four module numbers where EASA dropped it, so its number follows the EASA one here, as in 7/7A. Each module has a page of its own, with the EASA paper first and the UK CAA differences marked.