CAAB AME B1.2 flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Quadratic formula

For ax^2 + bx + c = 0, the roots are x = [-b +/- sqrt(b^2 - 4ac)] / 2a; the value b^2 - 4ac, the discriminant, shows whether real roots exist.

Sine rule

In any triangle, a / sin A = b / sin B = c / sin C, where each side is opposite the angle of the same letter. It is used when a side and its opposite angle are known.

Radians to degrees

Multiply radians by 180/pi to obtain degrees; one radian equals approximately 57.3 degrees, and a complete circle is 2 pi radians.

Kinetic energy

The energy a body possesses due to its motion, calculated as KE = 1/2 m v^2 where m is mass in kilograms and v is velocity in metres per second; the unit is the joule.

Pressure formula

Pressure equals force divided by area, p = F/A, measured in pascals. In a liquid at rest, pressure also equals density x gravity x depth, rho g h.

Speed of sound in air

Sound travels in air at about 340 metres per second at 15 degrees Celsius. The speed depends only on temperature and decreases as the air becomes colder.

Ohm's law

V = I R: the voltage across a resistance equals the current through it multiplied by the resistance in ohms. Rearranged, I = V/R and R = V/I.

Parallel resistance

For resistors in parallel, the reciprocal of the total equals the sum of the reciprocals: 1/RT = 1/R1 + 1/R2 + ... The total is always lower than the smallest resistor.

RMS value of sine wave

The root-mean-square value of a sine wave equals the peak value divided by 1.414, about 0.707 of peak. It is the effective value that produces equivalent heating.

Zener diode

A diode designed to operate in controlled reverse breakdown, holding an almost constant voltage across its terminals, so it is used as a voltage reference or simple regulator.

NPN transistor current gain

In an NPN transistor operating in the active region, collector current equals beta multiplied by base current, and the base-emitter junction requires about 0.7 volts forward bias for silicon.

Non-inverting amplifier gain

For an ideal operational amplifier circuit with feedback resistors Rf and Rin, the voltage gain equals 1 + Rf/Rin, and the output signal is in phase with the input.

De Morgan's theorem

NOT(A AND B) equals (NOT A) OR (NOT B), and NOT(A OR B) equals (NOT A) AND (NOT B). These identities allow logic circuits to be converted between gate types.

ARINC 429 bus

A unidirectional digital data bus using 32-bit words at 12.5 or 100 kilobits per second over a screened twisted pair, commonly linking avionic line-replaceable units that need parameter transfer.

ADC resolution

The smallest voltage step an analogue-to-digital converter can resolve equals the full-scale range divided by 2 raised to the power n, where n is the number of bits.

2024 aluminium alloy

An aluminium-copper alloy with high strength and good fatigue resistance but poor corrosion resistance. It is often clad with pure aluminium, known as Alclad, for aircraft skins.

Galvanic corrosion

Corrosion that occurs when two dissimilar metals are joined in the presence of an electrolyte; the more anodic metal corrodes, so carbon fibre and aluminium joints must be isolated.

Annealing

A heat treatment that softens a metal by heating it to a suitable temperature, soaking, then cooling slowly. It relieves internal stresses and restores ductility after cold working.

Lockwire

Safety wire, commonly 0.032 inch diameter for bolts, installed so that any tendency for the fastener to loosen pulls the wire tighter. About six to eight twists per inch.

Eddy current inspection

A non-destructive method using alternating magnetic fields to detect surface and near-surface cracks and changes in conductivity in conductive materials, without requiring direct contact with the part.

Certificate of Release to Service

A certification issued by authorised certifying staff after maintenance, confirming that the work has been completed satisfactorily and the aircraft or component is fit for release to service.

Induced drag

Drag created as a by-product of lift, caused by rearward-tilted lift and wingtip vortices. It is greatest at low speed and high angle of attack, and reduces as speed increases.

Critical angle of attack

The angle of attack at which airflow separates from the wing and lift decreases sharply. A stall occurs at this angle regardless of airspeed, weight or aircraft attitude.

Dihedral effect

The upward angle of wings from root to tip produces a rolling moment away from a sideslip. This gives positive lateral stability and a tendency to level the wings.

Dirty Dozen

Twelve human-factor precursors to maintenance error: fatigue, complacency, distraction, communication, resources, pressure, assertiveness, stress, awareness, teamwork, norms and knowledge.

SHELL model

A human factors model placing liveware, the person, at the centre interacting with software, hardware, environment and other liveware. Mismatches at these interfaces cause error.

Hypoxia

Insufficient oxygen reaching the body tissues. Symptoms include euphoria, impaired judgement and breathlessness, and at high altitude the time of useful consciousness may be only seconds.

ICAO Annex 1

The international standard covering personnel licensing, including requirements for flight crew, air traffic controllers and maintenance personnel, together with licensing and medical fitness provisions.

Airworthiness Directive

A mandatory requirement issued by the state of design or registry to correct an unsafe condition. It must be complied with within the stated time and the action recorded.

Minimum Equipment List

A document approved for a specific aircraft permitting flight with named equipment inoperative, subject to stated conditions, limitations and rectification intervals; it is derived from the master MEL.

Propeller slip

The difference between geometric pitch, the theoretical forward distance per revolution, and effective pitch, the distance actually advanced. Slip is normally expressed as a percentage of geometric pitch.

Feathering

Rotating the propeller blades to a high angle so they produce negligible thrust and minimum drag, used after an engine failure to reduce drag and vibration.