NZ CAA PPL Aircraft Technical common mistakes
NZ CAA PPL Aircraft Technical · Understand the traps and how to avoid them.
When asked to identify an airframe or engine component, the candidate names it only by its colloquial or everyday label (for example calling a control surface a 'flap' when the question is about an aileron) instead of using the correct technical name and describing its function.
Candidates learn component names passively from cockpit exposure and general reading rather than from a structured systems diagram, so similar-looking parts get merged in memory and the candidate answers from vague familiarity rather than precise knowledge.
What to do instead
Build a one-page labelled sketch of the airframe and the engine for each aircraft type studied, and for every part write a single sentence covering its name, location, and primary function. Test yourself by covering the labels and naming each part aloud, then reversing the exercise by listing functions and naming the part that performs each.
The candidate confuses the four-stroke cycle sequence or misattributes what happens on each stroke, for example stating that the mixture is ignited on the compression stroke or that the exhaust valve opens during the power stroke.
The cycle is memorised as a list of words (induction, compression, power, exhaust) without linking each stroke to piston direction, valve state, and the resulting change in pressure and temperature, so the sequence survives but the detail does not.
What to do instead
Draw the cycle as four panels showing piston direction, both valve positions, and what the air-fuel charge is doing in each. Then answer practice questions that ask what is happening at a specific point, such as 'both valves closed, piston moving up, charge being compressed'. Explain the cycle aloud from the drawing without looking at notes.
When asked how a system responds to a change, the candidate describes the cockpit control input rather than the system's actual behaviour, for example saying the carburettor heat control is pushed in to raise the temperature, or confusing which magneto position grounds which magneto.
Controls are learned by muscle memory in the aircraft, and the connection between control position and the underlying mechanism is rarely articulated, so the candidate recalls the action they perform rather than the physical result.
What to do instead
For each system control, write a two-column table: control position on the left, physical effect on the engine or airframe on the right. Include the abnormal cases, such as what happens if a magneto ground wire breaks. Rehearse the table until the physical effect, not the hand movement, is the first thing recalled.
The candidate treats indicated airspeed, calibrated airspeed, true airspeed, and groundspeed as interchangeable, and answers a performance question using the wrong one, for example computing a take-off distance from groundspeed or a heading from true airspeed without applying wind.
In everyday flying the numbers on the instrument are used loosely, and the corrections between them are small at low altitude, so the distinction is never forced. Under exam pressure the candidate grabs whichever speed value appears in the question.
What to do instead
Write out the chain from indicated to calibrated to true to groundspeed, naming the correction applied at each step (position error, density altitude, wind) and the direction of the error. Practise questions that give one value and ask for another, and state the correction explicitly before calculating.
When a performance question involves density altitude, the candidate uses aerodrome elevation or pressure altitude directly, or applies a temperature correction in the wrong direction, producing a take-off or climb performance figure that is too optimistic.
Density altitude requires two separate corrections and candidates collapse them into one, or they remember that 'hot and high is bad' without being able to compute the number, so they estimate instead of calculating.
What to do instead
Work the calculation in fixed steps every time: pressure altitude from elevation and QNH, then temperature deviation from ISA, then the density altitude from the chart or rule. Do at least ten worked examples across hot, cold, high, and low cases, and check each result against the expected direction of change before moving on.
The candidate confuses weight and balance terms, mixing basic empty weight, basic operating weight, maximum take-off weight, and zero fuel weight, or places an item in the wrong moment arm when computing the centre of gravity.
The definitions overlap and differ slightly between aircraft types and documentation, and candidates memorise the abbreviations without a clear picture of what is included in each, so items get double-counted or omitted.
What to do instead
Draw a stack diagram of the mass breakdown from empty weight upward, writing beside each level exactly what is included and excluded. Then compute a full loading problem from scratch, listing every item with its arm and moment, and verify the total against the maximum permitted values and the centre of gravity envelope.
The candidate answers a loading question by checking only that the total weight is under the maximum, without checking that the centre of gravity lies within the forward and aft limits for that weight.
Weight is a single number that is easy to compare, while the centre of gravity envelope requires reading a chart or computing a moment, so the second check is skipped under time pressure or forgotten entirely.
What to do instead
Adopt a fixed two-part check for every loading question: total weight against maximum, then centre of gravity against the envelope at that weight. Practise with cases that are under weight but out of balance, and note the handling consequences of forward and aft limits so the check feels operationally necessary rather than procedural.
The candidate cannot state who may perform a given maintenance task, confusing pilot-permitted maintenance, maintenance performed by a licensed engineer, and work requiring certification, or misstates what must be entered in the aircraft logbooks and technical records after maintenance.
The rules are organised by who does the work and what document records it, and candidates study the privileges of each role in isolation without mapping tasks to roles and to paperwork, so the boundaries blur.
What to do instead
Build a three-column table: task, who may perform it, and what record or certification follows. Populate it with the common cases from the syllabus, including pilot maintenance, scheduled inspections, and defect rectification. Then answer scenario questions by naming the role and the record before choosing an option.
The candidate treats the airworthiness certificate, the certificate of registration, and the maintenance documentation as a single category, and cannot say which document proves what, how long each remains valid, or what happens when one is missing or expired.
The documents travel together in the aircraft folder and are rarely examined individually in flight, so candidates learn them as a bundle and never attach a distinct purpose and validity rule to each.
What to do instead
Make a document matrix with one row per document and columns for purpose, issuing authority, validity or review period, and consequence if missing or expired. Recite the matrix from memory, then answer questions that remove one document at a time and ask whether the flight may proceed.
When a question describes a defect or an instrument indication, the candidate jumps to the most dramatic possible cause instead of reasoning from the indication to the most probable cause and the correct immediate action.
Case-based questions reward systematic reasoning, but candidates answer from alarm or from a single remembered anecdote, and they have not practised linking a specific indication to its likely system fault.
What to do instead
For each instrument and warning studied, write the normal indication, the common abnormal indications, the most likely cause of each, and the immediate action. Practise scenario questions by stating the indication, naming the system involved, ranking two or three possible causes, and only then selecting the action.