CAAB AME B1.2 common mistakes
CAAB AME B1.2 · Understand the traps and how to avoid them.
Converts units only at the end - or not at all - e.g. substitutes a diameter given in millimetres straight into a stress or area formula that assumes metres, then quotes the answer in N/mm² and Pa interchangeably.
Formulas are memorised as letter patterns from the formula sheet, so the units attached to each symbol are never treated as part of the calculation; time pressure then pushes the conversion to the last line, where it is dropped.
What to do instead
Before substituting, write every symbol with its SI unit (A = πd²/4 with d in m), convert at the start, and carry the units through each line of working so the final unit is the result of the arithmetic, not an afterthought.
Reuses the level-flight force picture for a climb or descent - stating lift = weight and thrust = drag, or omitting the weight component along the flight path when asked for thrust required.
The straight-and-level triangle is the diagram most heavily practised, so it is reproduced automatically instead of being redrawn for the flight condition stated in the question.
What to do instead
For every force question, redraw the free-body diagram for the stated condition first, then resolve parallel and perpendicular to the flight path (or to the horizontal) - never re-use a memorised triangle.
Applies DC rules to an AC circuit containing a capacitor or inductor: adds resistances arithmetically, uses I = V/R, and ignores reactance, impedance and phase angle.
DC practice problems dominate revision, and the reactive components look like simple components on the diagram, so the circuit is treated as resistive by default.
What to do instead
Before calculating, list every component in the circuit and tag it resistive or reactive; if anything is reactive, switch to impedance Z and state explicitly whether the working values of voltage and current are rms or peak.
Reads a signed binary value as unsigned - treating 1111 1111 as 255 when the question asks for the signed 8-bit value - and divides a bit rate by 8 without checking whether the answer is wanted in bits or bytes.
Routine conversion drills are practised almost entirely on positive unsigned numbers, and the words 'signed' and 'bits per second' in the stem are skimmed rather than read.
What to do instead
Check the stem for 'signed' before converting; for negatives use invert-and-add-one and sanity-check the magnitude; write 'bits ÷ 8 = bytes' as an explicit line before giving a rate.
Describes bolt grip length as the overall length under the head including the thread, and quotes thread length or shank diameter as if it were grip, when selecting a replacement fastener.
Grip, shank, thread length and overall length are four separate dimensions on the same item, and revision often memorises only one number per fastener type.
What to do instead
Write the definition before answering: grip is the unthreaded portion measured from under the head to the start of the thread, and it must equal the total thickness of the parts joined plus any washers.
Uses the torque wrench dial reading directly when the wrench is fitted with an extension or crows-foot, or converts between N·m and lbf·ft/lbf·in using the wrong factor.
Torque is treated as a single 'look up the figure and apply it' task, so the correction for a changed lever arm and the direction of the unit conversion are never considered.
What to do instead
Decide first whether the adaptor lengthens the lever arm; if it does, apply the appropriate correction rather than the dial figure. Convert units by writing the full factor chain (N·m → lbf·ft) and check the magnitude is sensible.
Treats angle of attack and pitch attitude as the same quantity, and assumes lift continues to rise as angle of attack is increased beyond the stall.
In level flight the two angles look similar on a sketch, so the distinction is not reinforced, and the lift curve is remembered as a straight line without the break at CLmax.
What to do instead
Define angle of attack as the angle between the chord line and the relative airflow, and pitch attitude as the angle between the longitudinal axis and the horizon, and state that lift peaks at the critical angle and then falls.
Classes an error wrongly - calling a skill-based slip a 'mistake', or a rule-based mistake a 'lapse' - and answers human-performance items from general experience instead of the model named in the syllabus.
Everyday English uses 'mistake' for any error, and the three categories are learned as vocabulary rather than as diagnostic definitions.
What to do instead
Apply the definitions in order before choosing: slip = right intention, wrong execution (attention); lapse = intended action omitted (memory); mistake = wrong intention or plan, rule-based or knowledge-based.
Answers a regulation item using familiar FAA or EASA rules rather than the CAAB Civil Aviation Regulations and associated orders, e.g. quoting the wrong recency/currency interval or naming the wrong person or organisation who may certify or approve a task.
Study material and online question sources are dominated by FAA/EASA content, so the non-CAAB figure feels correct and is chosen without checking the source document.
What to do instead
For every legislation item, first identify which document and which authority the stem is anchored to, then answer from that document; keep a one-page index of the CAR/ANO references in the syllabus and their subject matter.
Confuses blade angle, angle of attack and pitch on the propeller, and reverses the constant-speed governor's response - saying blade angle is reduced when rpm tends to rise above the selected value.
The three angles are described with similar words and the governor is learned as a block diagram, so the cause-and-effect direction is never traced.
What to do instead
Define blade angle (chord to rotation plane), angle of attack (chord to relative airflow) and pitch (forward distance per revolution) before reasoning, then trace the governor chain: rpm too high means more power absorbed, which means a larger blade angle.