CAAB AME B1.2 cheat sheet

Index laws: a^m x a^n = a^(m+n); a^m / a^n = a^(m-n); (a^m)^n = a^(mn); a^0 = 1; a^(-n) = 1/a^n.

Logarithms: log(ab) = log a + log b; log(a/b) = log a - log b; log(a^n) = n log a; ln is to base e, log to base 10 unless stated.

Quadratic formula: for ax^2 + bx + c = 0, x = [-b +/- sqrt(b^2 - 4ac)] / 2a; real roots exist only when b^2 - 4ac is zero or positive.

Trigonometry: sin = opposite/hypotenuse, cos = adjacent/hypotenuse, tan = opposite/adjacent = sin/cos; Pythagoras gives hypotenuse^2 = sum of the squares of the other two sides.

Sine rule a/sin A = b/sin B = c/sin C; cosine rule a^2 = b^2 + c^2 - 2bc cos A.

Areas and volumes: circle area = pi r^2, circumference = 2 pi r; cylinder volume = pi r^2 h; sphere volume = (4/3) pi r^3, surface = 4 pi r^2.

Angle conversion: radians = degrees x pi/180; degrees = radians x 180/pi; one radian is approximately 57.3 degrees.

Percentage change = (new value - old value) / old value x 100; a value increased by p percent is multiplied by (1 + p/100).

Newton's second law: F = ma; weight is a force, W = mg, with g approximately 9.81 m/s^2.

Work = force x distance moved in the direction of the force (joule); power = work done per unit time (watt); efficiency = useful output / input x 100 percent.

Kinetic energy = 1/2 m v^2; change in potential energy = m g h.

Pressure p = F/A in pascals; in a liquid at rest p = rho g h; 1 bar = 100 kPa; gauge pressure = absolute pressure - atmospheric pressure.

Density rho = mass / volume; relative density = density of the substance / density of pure water.

Temperature: K = degrees C + 273.15; degrees F = (degrees C x 9/5) + 32.

Heat energy Q = m c dT for a temperature change and Q = m L for a change of state; c is specific heat capacity, L is specific latent heat.

Wave relation v = f x lambda; sound in air travels at about 340 m/s at 15 degrees C, and the speed falls as temperature falls.

General gas equation pV = nRT; for a fixed mass of gas, p1 V1 / T1 = p2 V2 / T2 with temperatures in kelvin.

Ohm's law V = I R; power P = V I = I^2 R = V^2 / R.

Resistors in series add directly; for parallel resistors 1/RT = 1/R1 + 1/R2 + ... and RT is always less than the smallest resistor.

Kirchhoff's current law: the algebraic sum of currents at a junction is zero; voltage law: the sum of e.m.f.s around a loop equals the sum of potential differences.

Capacitance C = Q/V; capacitors in parallel add, in series 1/CT = 1/C1 + 1/C2; energy stored = 1/2 C V^2.

Inductors in series add, in parallel 1/LT = 1/L1 + 1/L2; energy stored = 1/2 L I^2.

For a sine wave, rms value = peak value / sqrt(2) (about 0.707 of peak); frequency f = 1/T.

Reactance X_L = 2 pi f L and X_C = 1 / (2 pi f C); impedance Z = sqrt(R^2 + (X_L - X_C)^2).

Ideal transformer: V1/V2 = N1/N2 and V1 I1 = V2 I2, so stepping voltage up steps current down.

In a balanced star system, line voltage = sqrt(3) x phase voltage and line current equals phase current.

Silicon diodes drop about 0.7 V when forward biased and germanium about 0.3 V; reverse biased they conduct only a small leakage current.

Half-wave rectification uses one diode; full-wave bridge rectification uses four diodes and gives twice the ripple frequency.

A zener diode is used reverse biased in its breakdown region to hold a nearly constant voltage for regulation or reference.

NPN transistor in the active region: collector current = beta x base current; base-emitter forward bias is about 0.7 V for silicon.

Ideal op-amp: infinite open-loop gain and input impedance, zero output impedance; inverting gain = -Rf/Rin, non-inverting gain = 1 + Rf/Rin.

An LED needs a series resistor to limit current; forward drop is typically 1.8 to 3.3 V depending on colour.

A photodiode is operated reverse biased and its leakage current increases with light; a phototransistor gives current gain but slower response.

A capacitor in parallel with a load smooths a rectified supply (low-pass); a series inductor opposes changes in current.

Binary place values are 1, 2, 4, 8, 16, 32...; hexadecimal uses digits 0-9 and A-F, each hex digit representing four binary bits.

AND gives 1 only when all inputs are 1; OR gives 1 when any input is 1; XOR gives 1 for an odd number of 1s; NAND and NOR are the inverted forms.

De Morgan: NOT(A AND B) = (NOT A) OR (NOT B); NOT(A OR B) = (NOT A) AND (NOT B).

ARINC 429 is a unidirectional bus carrying 32-bit words at 12.5 or 100 kbit/s over a screened twisted pair, typically one transmitter to several receivers.

ARINC 664 (AFDX) is a switched full-duplex Ethernet-based network at 100 Mbit/s using virtual links and dual redundant networks.

MIL-STD-1553B is a 1 Mbit/s command/response bus with a bus controller, remote terminals and dual redundant channels.

ADC resolution = full-scale range / 2^n for an n-bit converter; quantisation error is at most half a least significant bit.

EFIS displays present primary flight data, navigation data and engine/system parameters; CRT, LCD and LED are the common display technologies.

2024 (aluminium-copper) has high strength and good fatigue resistance but poor corrosion resistance, so it is often clad as Alclad; 7075 (aluminium-zinc) is stronger but less corrosion resistant.

6061 (aluminium-magnesium-silicon) is weldable and corrosion resistant but lower in strength than 2024 or 7075.

Titanium alloys give a high strength-to-weight ratio and retain strength at high temperature; titanium machining carries a fire risk and needs special precautions.

Austenitic 300-series stainless steels are corrosion resistant and non-magnetic; 400-series martensitic steels are magnetic and hardenable by heat treatment.

AN bolts are identified by diameter in sixteenths of an inch (AN3 = 3/16 in); NAS bolts are close-tolerance, and grip length must match the joint thickness.

2117-T3 (AD) rivets are driven as received; 2024-T4 (D) rivets must be refrigerated and used within their out-of-refrigerator life.

Carbon fibre composites give high stiffness and strength but cause galvanic corrosion of aluminium; aramid (Kevlar) offers good impact and abrasion resistance.

Precipitation hardening: solution treatment, quench, then natural or artificial ageing; annealing softens and relieves internal stress.

Corrosion forms include galvanic, pitting, intergranular, stress corrosion and fretting; aluminium corrosion shows white powder, steel shows red rust.

Torque values from the manual are applied with a calibrated wrench set to the stated units; a torque wrench is never used to loosen or as a breaker bar.

Lockwire is normally 0.032 in for bolts; it is installed so that any loosening tendency pulls the wire tighter, with about 6 to 8 twists per inch.

NDT methods: dye penetrant for surface-breaking defects, magnetic particle for ferrous surface and near-surface defects, eddy current for surface defects and conductivity, ultrasonic and radiographic for internal defects.

Before refuelling, the aircraft and fuel source are bonded and earthed to prevent static discharge; no ignition sources within the marked zone.

Scheduled checks are typically A-check (light, frequent), C-check (intermediate) and D-check (heavy structural); MSG-3 tasks are task-oriented and derived from system and structural analysis.

Correct data must be used: AMM for maintenance, IPC for parts, SRM for structural repair; approved data is required for repairs and alterations.

Flight control rigging checks cable tension, control surface travel and neutral positions against the maintenance manual limits.

Weighing and balancing determines empty weight and centre of gravity; ballast or equipment changes require re-weighing or calculation per the manual.

Bernoulli's theorem: in a streamline, an increase in velocity is accompanied by a decrease in static pressure and total pressure stays constant.

Lift L = 1/2 rho V^2 S C_L and drag D = 1/2 rho V^2 S C_D; both vary with the square of airspeed at constant angle of attack.

Parasite drag increases with V^2; induced drag falls as speed increases, so total drag is minimum at the speed for best lift/drag ratio (best glide).

A wing stalls at the critical angle of attack (about 15 to 18 degrees for most aerofoils), independent of airspeed, weight and attitude.

The speed of sound depends only on temperature: about 1225 km/h (661 kt) at sea level ISA and lower in cold air; Mach number = TAS / local speed of sound.

Wing sweepback delays the onset of shock-induced separation at high Mach number and adds lateral stability, but tends to produce Dutch roll.

Dihedral gives positive lateral (roll) stability by creating a rolling moment away from a sideslip; anhedral is used where too much dihedral would cause spiral instability.

Aspect ratio = span^2 / area; a high aspect ratio reduces induced drag but increases structural bending loads.

The boundary layer starts laminar and becomes turbulent; a turbulent boundary layer has more energy and resists separation better than a laminar one.

SHELL model: Liveware (the person) at the centre interacting with Software, Hardware, Environment and other Liveware; error arises where these interfaces mismatch.

The Dirty Dozen: fatigue, complacency, distraction, lack of communication, lack of resources, pressure, lack of assertiveness, stress, lack of awareness, lack of teamwork, norms and lack of knowledge.

Vision: cones in the fovea give colour and detail in daylight; rods in the periphery give poor-resolution night vision, and full dark adaptation takes about 30 minutes.

Hypoxia symptoms include euphoria, impaired judgement, tingling and breathlessness; time of useful consciousness falls rapidly with altitude.

Noise above about 85 dB can cause hearing damage; hearing loss from noise is cumulative and irreversible, so hearing protection is required on the ramp.

Reason's model: unsafe acts (slips, lapses, mistakes, violations) combine with latent organisational conditions, like holes in slices of Swiss cheese.

Effective communication uses standard phraseology, readback of clearances and assertiveness when a task or instruction appears unsafe.

ICAO Annex 1 covers personnel licensing, Annex 6 operation of aircraft and Annex 8 airworthiness of aircraft; national regulations implement these standards.

EASA Part-66 defines maintenance licence categories: A (limited line certification), B1 (mechanical), B2 (avionics) and C (base maintenance certifying staff).

Part-145 covers approved maintenance organisations; Part-M / Part-CAMO covers continuing airworthiness management; Part-21 covers design and production.

A Certificate of Release to Service must be issued by authorised certifying staff after maintenance and before flight, and certification responsibility cannot be delegated.

Airworthiness Directives are mandatory and must be complied with in the stated time; Service Bulletins are advisory unless an AD makes them mandatory.

The Minimum Equipment List, derived from the Master MEL, permits flight with specified items inoperative within stated conditions, limitations and rectification intervals.

Maintenance records must be retained for the periods set by the authority and kept legible and traceable to the aircraft, component and task.

Configuration control uses the revision status of manuals; work must only be carried out to the current approved data applicable to the aircraft type.

Blade angle of attack = blade angle (pitch angle) minus helix angle; the helix angle depends on rotational speed and forward speed.

Geometric pitch is the theoretical forward distance per revolution; effective pitch is the actual distance advanced; slip is the difference, usually quoted as a percentage of geometric pitch.

Fixed-pitch propellers are pitched coarse for cruise speed or fine for climb and acceleration; a constant-speed propeller varies blade angle to hold a selected rpm.

A propeller governor controls blade angle with engine oil pressure to keep rpm constant as load or airspeed changes.

Feathering turns the blades to a high angle producing negligible thrust and minimum drag; it needs stored oil pressure or an accumulator to feather after engine stoppage.

Forces on a propeller include centrifugal, thrust, torque reaction, gyroscopic precession and asymmetric blade effect (P-factor), the last being greatest at high angle of attack.

Propeller tip speed must stay below the speed of sound; reduction gearing lowers propeller rpm relative to engine rpm.

Propeller vibration is controlled by static and dynamic balancing and by tracking; blade damage limits, track limits and tip clearance are given in the maintenance manual.