EASA Module 4 case studies
EASA Module 4 · Put your knowledge to work in context.
EASA Part-66 Module 4, Electronic Fundamentals, is one of the knowledge modules that make up the theoretical training requirement for an aircraft maintenance licence under the European aviation maintenance training system. It sits alongside the other basic knowledge modules and is normally delivered by a Part-147 approved maintenance training organisation, either as a full course or as a bridging module for candidates extending an existing licence category. The EASA Module 4 case studies are 5 cases and about 3,785 words.
1Zener Regulator Failure on a 28 V Bus
A line-replaceable unit takes power from a 28 V DC bus (25.2 V to 30.8 V in service) and derives a 12 V rail for a 20 mA sensor load using a series resistor and a 1N4742A zener. The zener is rated 12 V, 1 W at 25 °C, derating linearly at 10 mW/°C above 50 °C, and its knee current is 5 mA.
789 words, about 4 min2Relay Driver That Never Saturates
A fuel-pump relay is switched by a BC337 NPN driven from a 3.3 V microcontroller GPIO. The relay coil is 12 V, 120 Ω, inductance 0.4 H.
739 words, about 4 min3A 3 A Power Track on 1 oz Copper
A 5 V, 3 A supply feeds a payload board through a single 100 mm long, 0.30 mm wide track on the outer layer of a 1 oz (35 µm) FR-4 board. Copper resistivity is 1.72 × 10⁻⁸ Ω·m and the temperature coefficient is 0.0039 per °C; 1 mil = 0.0254 mm.
675 words, about 3 min4Intermittent Tombstoning on an 0402 Capacitor
A six-layer control board carries 240 identical 0402 100 nF decoupling capacitors. After a change of contract manufacturer, 3.2 % of the C41 position tombstone - one termination lifts clear of its land.
769 words, about 4 min5Slow Traverse and Standing Error on a Positioner
A single-axis actuator uses a 24 V brushed dc motor rated 3600 rpm at 24 V no load, a 30:1 gearbox and a 5 mm-pitch leadscrew; total travel is 150 mm. Feedback is a potentiometer over the full stroke feeding a 12-bit ADC (0–5 V mapped to 0–150 mm).
813 words, about 4 min