CAAB AME B1.1 Exam flashcards

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

Centre of gravity

The point at which the total mass of the aircraft may be considered concentrated. Its position, expressed as a distance from the datum, must remain within the certified forward and aft limits in all loading conditions.

Moment arm definition

The perpendicular distance from the datum or reference axis to the line of action of a force or to a mass item. Moment equals force or weight multiplied by this distance, giving units such as newton-metres or kg-inches.

Datum in mass and balance

A fixed reference plane, defined by the manufacturer, from which all arms are measured. It may lie ahead of the nose, inside the aircraft, or at the firewall, and it never moves with loading.

Basic empty mass

The mass of the aircraft with structure, powerplant, systems, unusable fuel, and optional equipment included, plus full operating fluids. It excludes crew, passengers, usable fuel, and payload, and forms the starting point of the load sheet.

Maximum take-off mass

The highest mass at which the aircraft is certified to begin the take-off run. It is a structural and performance limit and must not be exceeded even if the runway is long and the weather is favourable.

Continuity equation

For steady flow of an incompressible fluid, the product of cross-sectional area and velocity is constant along a streamtube. A narrowing duct therefore increases flow velocity and reduces static pressure.

Bernoulli's principle

In steady, frictionless, incompressible flow, the sum of static pressure, dynamic pressure, and potential energy per unit volume is constant along a streamline. Faster-moving fluid therefore has lower static pressure.

Dynamic pressure

The pressure arising from fluid motion, equal to one half the density multiplied by the square of velocity. It represents the kinetic energy per unit volume and is used in airspeed measurement.

Pitot-static principle

Total pressure from the forward-facing pitot tube is compared with static pressure from a flush port. The difference is dynamic pressure, which is converted to indicated airspeed by the air data instruments.

Boyle's law

At constant temperature, the pressure of a fixed mass of gas is inversely proportional to its volume. Compressing a gas in a closed container raises its pressure proportionally.

Charles's law

At constant pressure, the volume of a fixed mass of gas is directly proportional to its absolute temperature. Heating a trapped gas expands it, which is relevant to sealed cabin and accumulator servicing.

Pascal's law

Pressure applied to a confined fluid is transmitted undiminished in all directions and acts at right angles to the containing surfaces. This underlies hydraulic braking and actuation systems.

Hydraulic force multiplication

Force equals pressure multiplied by piston area. A small input piston driving a large output piston produces a larger output force, though the output piston moves a proportionally shorter distance.

Ohm's law

Current through a conductor is directly proportional to the potential difference across it and inversely proportional to resistance. Expressed as voltage equals current multiplied by resistance.

Electrical power formula

Power dissipated in a direct-current circuit equals voltage multiplied by current, and also equals current squared multiplied by resistance, or voltage squared divided by resistance.

Parallel resistance rule

The reciprocal of total resistance equals the sum of the reciprocals of the individual resistances. Total resistance is always less than the smallest individual resistance in the network.

Series circuit behaviour

In a series circuit the same current flows through every component, the supply voltage divides across the components, and total resistance is the arithmetic sum of the individual resistances.

Shear stress

Stress produced by forces acting parallel to a cross-section, tending to slide one layer of material over another. It is calculated as shear load divided by the resisting area.

Young's modulus

The ratio of tensile stress to tensile strain within the elastic limit of a material. A higher value indicates a stiffer material that deflects less under the same applied load.

Fatigue failure

Failure caused by repeated or fluctuating stress below the ultimate strength, often starting at a stress raiser such as a hole or scratch. Cracks propagate progressively until the remaining section fractures.

Stress raiser

A local feature such as a sharp corner, hole, scratch, or corrosion pit that concentrates stress above the nominal level. Smooth radii and careful surface protection reduce its severity.

Galvanic corrosion

Corrosion occurring when two dissimilar metals are in electrical contact in the presence of an electrolyte. The more anodic metal corrodes, so protective barriers and compatible fasteners are essential.

Aluminium 2024 alloy

A copper-bearing aluminium alloy with high strength and good fatigue resistance, widely used for aircraft skins. Its corrosion resistance is poor, so it is normally supplied clad with pure aluminium.

Aluminium 7075 alloy

A zinc-bearing aluminium alloy with very high strength used for highly loaded structure such as wing spars and fittings. It has low corrosion resistance and is sensitive to stress-corrosion cracking.

Aluminium 6061 alloy

A magnesium-silicon aluminium alloy that is readily weldable, corrosion resistant, and reasonably strong. It is used for structures and fittings where welding or corrosion resistance matters more than peak strength.

Anodising process

An electrolytic treatment that thickens the natural oxide layer on aluminium, improving corrosion resistance and providing a key for paint. The coating is brittle and reduces fatigue performance of thin sections.

Sacrificial anode

A more anodic metal deliberately coupled to a structure so that it corrodes preferentially, protecting the structure. Zinc or magnesium anodes are common on immersed or buried steel components.

Lockwire purpose

A safety device that prevents fasteners from rotating under vibration. The wire is installed so that any tendency to loosen pulls the wire in the tightening direction of the adjacent fastener.

Torque wrench calibration

Torque tools must be verified against a traceable standard at defined intervals and after repair or overload. An out-of-calibration wrench invalidates the recorded torque values of any joint it tightened.

A-check inspection

A relatively light and frequent maintenance check, typically performed at a line station overnight. It covers visual inspections, fluid levels, and selected operational checks defined by the maintenance programme.

C-check inspection

A heavier, less frequent maintenance check usually carried out in a hangar with access panels opened. It includes detailed inspections, functional tests, and replacement of components at defined intervals.

D-check inspection

The heaviest structural maintenance check, performed at long intervals and requiring extensive disassembly. It involves detailed inspection of the airframe structure and major refurbishment before return to service.