CAA NZ AME Electrical common mistakes
CAA NZ AME Electrical · Understand the traps and how to avoid them.
Treating Ohm's law and power formulas as interchangeable by plugging in a voltage or resistance without checking which quantity is actually known, so answers come out with the wrong unit or an order-of-magnitude error.
Candidates memorise V=IR and P=VI but practise them in isolation; under exam pressure they substitute a value from the question stem into the wrong variable, or forget that P=I²R and P=V²/R give the same result only when the correct quantity is used.
What to do instead
Before any calculation, write the three known quantities and the unit of the answer, then select the formula that uses only those quantities. Practise a mixed set of series, parallel and series-parallel circuits where you must choose the formula rather than apply a named one.
Calculating total resistance in a parallel network by adding the branch resistances, or forgetting to invert the reciprocal sum at the end of the 1/R calculation.
The series rule is learned first and reinforced by everyday intuition that more paths mean more resistance; the reciprocal step is also easily dropped as a final arithmetic slip.
What to do instead
Use the product-over-sum shortcut for two branches (R1R2/(R1+R2)) and the reciprocal method for three or more, and sanity-check every parallel answer: total resistance must be smaller than the smallest branch.
Confusing the behaviour of AC and DC in inductors and capacitors, for example stating that a capacitor blocks DC but passes AC while attributing the opposite behaviour to an inductor, or ignoring reactance when computing impedance.
The two components are studied together and the phase relationships are abstract; candidates recall that 'one blocks DC' without anchoring which component and why.
What to do instead
Anchor each rule to a physical mechanism: a capacitor is an open circuit to steady DC because the dielectric prevents conduction, and an inductor is a short to steady DC because the winding is continuous. Then practise impedance calculations combining resistance with reactance.
Reading a wiring diagram or schematic and assuming wire colours, terminal numbers or connector pin letters follow a universal convention rather than the aircraft-specific standard shown in the documentation.
Training examples often use one manufacturer's convention, and candidates transfer that habit to questions describing a different aircraft or standard.
What to do instead
Treat every diagram question as requiring you to read the legend and notes first. Practise interpreting schematics that include a legend, and state the standard being applied before answering.
Mixing up the roles of the battery, the generator or alternator, and the external power receptacle when tracing how a system is powered in normal, abnormal and emergency configurations.
Candidates memorise component functions individually but do not rehearse the power-flow logic through contactors, relays and bus ties, so they misidentify which source feeds a bus in a given failure state.
What to do instead
Draw the power distribution single-line diagram from memory for a typical twin-engine aircraft, labelling each contactor and bus, then trace three scenarios: normal, one generator failed, and battery-only. Repeat until the flow is automatic.
Assuming a generator or alternator fault will always illuminate a cockpit warning, rather than recognising that some failures (for example an open field circuit or a failed voltage regulator) show up only as abnormal bus voltage or a loadmeter reading.
Warning-light logic is over-simplified in study notes, and candidates do not connect indicator behaviour to the underlying control circuit.
What to do instead
Learn the generator control unit functions and what each cockpit indication actually measures (voltage, current, frequency). For each indication, write the fault it would and would not reveal.
Describing bonding and grounding checks without distinguishing between the resistance limits for primary structure bonding and for equipment case bonding, or omitting the requirement to use a bonding meter rather than an ordinary multimeter.
Both are 'resistance to structure' checks and the limits blur together; the instrument requirement is a practical detail rarely emphasised in theory study.
What to do instead
Build a table of bonding points with their applicable resistance limits and the approved test instrument for each, sourced from the maintenance manual, and recall it as paired facts rather than a single number.
Specifying a wire gauge or repair scheme from memory instead of from the applicable approved data, or substituting a wire of equal current rating but different insulation or temperature rating.
Candidates focus on current-carrying capacity alone and overlook voltage drop, bundling derating, insulation type and temperature class, which are the factors the approved data actually controls.
What to do instead
For every wiring question, identify the approved data source first (maintenance manual, wiring diagram manual, or standard wiring practices manual) and check the answer against derating and insulation requirements before committing.
Treating a maintenance action as complete once the task is physically finished, without recording the reference document, revision status, and sign-off in the required format, or signing for work not personally performed or inspected.
Technical training rewards hands-on competence, and documentation is treated as paperwork to be done later; candidates also underestimate how strictly certification and release-to-service rules are examined.
What to do instead
Rehearse the release-to-service sequence as a fixed checklist: approved data referenced, task certified by an authorised person, independent inspection where required, and entry made in the correct document. Practise writing a sample certification entry.
Underestimating the effect of fatigue, shift patterns, time pressure and unfamiliarity on error rates, and answering human-factors questions with the assumption that a licensed engineer will not make mistakes if they are careful.
Human factors is often studied as a list of names and models rather than as a working understanding of how errors arise in real maintenance environments, so scenario questions are answered with intuition rather than the framework.
What to do instead
Learn one error model (for example the slip, lapse, mistake and violation distinction) and one performance-shaping framework, then apply them to written scenarios such as a night shift before an early departure. Practise identifying the specific error type and the barrier that would have prevented it.