Iran CAO Part-66 AMT Theory flashcards

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

Sine rule

In any triangle, each side divided by the sine of its opposite angle is constant: a/sin A = b/sin B = c/sin C. Used to solve non-right triangles when one side and two angles are known.

Cylinder volume formula

Volume equals π times the square of the radius times the height, V = πr²h. Useful for calculating fluid capacity of tanks, struts and pipe sections in maintenance work.

Newton's second law

Force equals mass times acceleration, F = ma. One newton accelerates one kilogram at one metre per second squared; weight is mass times gravitational acceleration, W = mg.

Hydrostatic pressure

Pressure at depth in a fluid equals density times gravitational acceleration times depth, p = ρgh. It depends only on depth and fluid density, not on container shape.

Latent heat

Heat absorbed or released during a phase change with no temperature change, Q = mL. Latent heat of vaporisation converts liquid to vapour; fusion converts solid to liquid.

Parallel resistance

The reciprocal of total resistance equals the sum of reciprocals of individual resistances. Total resistance is always less than the smallest branch, and voltage is common across branches.

Resonance in AC circuits

At the frequency where inductive and capacitive reactance are equal, they cancel and impedance equals resistance alone. Current is maximum and power factor is unity at that point.

RMS versus peak voltage

For a sine wave, the root-mean-square value equals the peak value divided by the square root of two, about 0.707 times peak. RMS gives the equivalent heating effect.

Zener diode function

A diode operated in reverse breakdown holds a nearly constant voltage across it. Used with a series resistor to regulate supply voltage and protect sensitive circuits.

Transistor current gain beta

In the active region, collector current equals beta times base current, I_C = βI_B. Beta typically ranges from tens to hundreds and varies with temperature and collector current.

Operational amplifier inverting gain

With negative feedback through R_f from output to inverting input and R_in to that input, voltage gain equals minus R_f divided by R_in. The input is a virtual earth.

ARINC 429 word format

A 32-bit word with label, source/destination identifier, data field, sign/status bits and odd parity. Transmission is one-way on a twisted pair at 12.5 or 100 kbit/s.

ADC resolution

Resolution equals full-scale voltage divided by two raised to the number of bits. A 12-bit converter over 10 volts resolves about 2.44 millivolts per step.

Two's complement negation

To negate a binary number, invert all bits and add one. An n-bit signed value ranges from minus two to the power n minus one up to that power minus one.

Alclad aluminium sheet

Aluminium alloy sheet clad on both faces with a thin layer of commercially pure aluminium. The cladding gives sacrificial corrosion protection to the stronger core alloy.

Fastener grip length

The unthreaded portion of a bolt shank measured from the underside of the head. Grip must match material thickness so threads do not bear in the shear plane.

Lockwire installation standard

Safety wire is installed so tension pulls the fastener clockwise, with six to eight twists per inch and a pigtail of about three to six millimetres turned under.

Magnetic particle inspection

Detects surface and near-surface defects in ferromagnetic parts by magnetising the part and applying iron particles that gather at flux leakage around discontinuities.

Certificate of release to service

A certification that maintenance has been completed and the aircraft is fit for return to service. It is issued by authorised certifying staff within their licence scope.

Dye penetrant inspection

A surface inspection method where penetrant enters surface-breaking defects, is drawn out by developer, and shows as an indication under ultraviolet or white light.

Continuity equation

For steady flow in a streamtube, density times area times velocity is constant. Where the cross-section narrows, velocity increases and static pressure falls.

Critical Mach number

The free-stream Mach number at which airflow somewhere on the airframe first reaches Mach one. Beyond it, shock waves and drag rise appear.

Induced drag behaviour

Drag caused by lift generation, strongest at low speed and high angle of attack. It decreases as speed rises and increases with the square of the lift coefficient.

Time of useful consciousness

The interval between loss of oxygen supply and inability to act effectively. At 35,000 feet it is roughly 30 to 60 seconds without supplemental oxygen.

Somatogravic illusion

A false pitch sensation caused by linear acceleration or deceleration. Acceleration is perceived as nose-up attitude, prompting a pilot to push forward incorrectly.

Category B2 licence scope

The B2 aircraft maintenance licence covers avionics and electrical systems on aircraft. Holders certify avionics maintenance and may perform defined mechanical tasks after appropriate training.

Airworthiness directive status

A mandatory requirement issued by the airworthiness authority to correct an unsafe condition. Compliance is obligatory within stated limits and must be recorded.

Minimum equipment list

An operator-approved document allowing dispatch with specific equipment inoperative, subject to stated conditions, limitations and maintenance procedures. It is not a permission to defer any defect.

Dissymmetry of lift

In forward flight the advancing blade sees higher relative airflow than the retreating blade, creating unequal lift. Flapping and cyclic feathering equalise lift across the disc.

Translational lift

Improved rotor efficiency as forward speed carries the rotor out of its own downwash. Power required falls, typically becoming significant above about 15 to 20 knots.

Vortex ring state

A condition with low airspeed, high descent rate and power applied, where recirculating air destroys rotor lift. Recovery uses forward cyclic and reduced collective.

Swashplate function

A rotating and non-rotating assembly that transfers pilot cyclic and collective inputs to the blade pitch links, changing blade pitch cyclically and collectively.