EASA Part-66 Module 4: Electronics Fundamentals

The table starts with the simplest thing a circuit can be built from and works its way up. Semiconductors take the top of it: diodes at 4.1.1, transistors at 4.1.2, then integrated circuits at 4.1.3, where a whole circuit arrives inside one part. From there, 4.2 turns to the board all three get soldered to, and 4.3 leaves hardware behind altogether for servomechanisms, which are an arrangement rather than a thing. The deepest requirement anywhere in the module is the diode row at 4.1.1(a), “description and characteristics” in the EASA table, and it sits at level 2, where understanding the theory and reading a schematic are part of the requirement rather than describing the subject.

A diode passes current one way and blocks it the other, and that single property carries more of an aircraft than its size suggests. It’s how the alternating current a generator produces becomes the direct current a bus can live with, inside a transformer rectifier unit, and it’s also the small diode across a relay coil, absorbing the spike a collapsing magnetic field throws out, which would otherwise pit the contacts that switched it. Under EASA the row goes further than the name suggests: its guidance lists diode symbols and properties, diodes in series and parallel, P and N type materials, the PN junction unbiased, forward biased and reverse biased, the diode’s parameters, and devices that include the thyristor, the light emitting diode, the photoconductive diode and the rectifier diode.

Transistors and integrated circuits follow, both at level 1. A transistor uses a small current to control a much larger one, which makes it a switch with nothing inside to wear out and, biased between its extremes, an amplifier, and EASA’s 4.1.2(a) asks for its symbol, its orientation and its characteristics, leaving how it is built to the row below. An integrated circuit is that trick repeated until a whole circuit fits on a chip you could lose in the carpet, and EASA’s 4.1.3(a) asks for the description and operation of logic circuits, linear circuits and operational amplifiers: logic circuits deal in ones and zeros, linear circuits in signals that vary continuously.

Printed circuit boards get a topic to themselves at 4.2. A board is what replaced wiring one component to the next by hand: copper tracks etched onto an insulating laminate, components soldered to pads or mounted straight onto the surface, and a conformal coating against moisture and salt. What matters to a B1.1 engineer is handling rather than manufacture: the damage you can personally do is electrostatic discharge, where a charge far too small to feel can destroy a device outright or wound it so it fails weeks later on somebody else’s shift.

Servomechanisms close the module at 4.3, and their place in an electronics paper rather than a systems one tells you what they are: an idea rather than a box. The requirement here is the principle, at level 1, and EASA’s guidance for that row is a list of terms that includes open and closed loop systems, feedback, follow up, null, overshoot, damping, deadband, hunting, and synchro systems, the transmitter and receiver pairs that carry a shaft angle down three wires so a flap on the wing can tell an indicator on the flight deck where it has got to. Construction and operation sit on the row below, and that row carries a dash.

The EASA paper puts 20 multiple choice questions inside 25 minutes, each with three answers and one right, and no paper in the whole of category B1.1 is shorter. EASA’s acceptable means of compliance then spread them very unevenly: 8 on diodes, 4 on transistors, 3 on integrated circuits, 2 on printed circuit boards and 3 on servomechanisms, and a paper may depart from that with justification provided it still totals 20. Short doesn’t mean quick to read, though: the subjects sit very close together in Module 4, and a stem about a diode and a stem about a transistor can look alike until their last line, so the time is best spent reading each question to its full stop before looking at anything underneath it.

The 75% pass mark puts the target at 15 correct answers and leaves 5 in reserve, and a short paper spends a reserve like that in a particular way, because there’s no back half to make anything up in. On a long paper, a poor opening is a poor opening and most of the sitting is still ahead of you. Here, what’s still ahead of you is a handful of questions, and a margin gone in the first few minutes is simply gone, so everything after it has to be right, and that’s a harder way to sit an exam than the size of the paper suggests.

Below is the EASA table: nine rows, four of them not required for category B1.1, and each required row showing its question count from EASA’s guidance. The UK CAA’s levels match EASA’s the whole way down, dashes included, and printed circuit boards at 4.2 is the only row the UK titles on its own, in the same words as EASA; every other UK row is a lettered part under a heading. What the levels can’t show is where each authority puts the detail. EASA’s required diode row carries the PN junction in its guidance, where the UK puts it on the deeper row B1.1 skips, so the same level in both columns does not mean the same reading.

First, by a single letter, in the module’s own name: the EASA text calls it Electronics Fundamentals and the UK CAA text calls it Electronic Fundamentals. That’s what the two regulations print rather than a slip in our table, and it matters mostly when you’re searching, because a provider quoting one spelling and a provider quoting the other are describing the same paper. The UK CAA’s paper is no different, 20 questions, 25 minutes and no essay; the UK CAA numbers it Module 4 and sets all nine rows at the level EASA does. Under the UK CAA, Module 8 and Module 9A match this paper on the multiple choice part, and 9A adds a written answer this one never has.

Second, and this is the difference that matters, in where the line between the two halves of each pair falls. In the UK table the materials and the PN junction sit on the deeper diode row, and servo defects, reversed synchro leads and hunting sit on the deeper servomechanisms row, both rows B1.1 is not required to read. EASA’s guidance moves that material up: P and N type materials and the PN junction sit under 4.1.1(a), the required level 2 row, and hunting, with null, damping and deadband beside it, sits among the principles in 4.3(a). A UK CAA candidate may therefore leave junction physics and hunting to the deeper rows, and an EASA candidate cannot. The movement runs one small step the other way too, because EASA puts the functional testing of diodes on its deeper 4.1.1(b), where the UK keeps it on the required row.

The rest is wording. Where EASA’s table heads the transistor row with “description and characteristics”, the UK row opens on transistor symbols, and its diode row names symbols too; EASA lists symbols in its guidance for both rows, so nothing is lost. On servomechanisms, EASA’s first heading stops at “principles” while the UK row spells out open and closed loop systems and synchro components, and EASA’s guidance names both. The required integrated circuit row doesn’t differ at all: both texts describe logic circuits, linear circuits and operational amplifiers on it. A UK CAA candidate revising from this page needs only to go lighter on the PN junction and on hunting, and to keep diode testing in view.

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.