CAA NZ AME Aeroplanes 1 (Subject 4) cheat sheet

Limit load is the maximum load expected in service; ultimate load is limit load multiplied by the factor of safety (typically 1.5 for aircraft structures).

Fail-safe design ensures that failure of a single structural element will not cause catastrophic failure; damage-tolerant design uses inspectability and crack-growth analysis.

Shear panels carry load through diagonal tension; riveted joints transfer load via shear and bearing, with edge distance at least 2D for aluminium alloys.

Stress = Load / Area (σ = P/A); strain = Change in length / Original length (ε = ΔL/L); Young's modulus E = σ/ε in the elastic region.

Bending stress in a beam: σ = M·y / I, where M is bending moment, y is distance from neutral axis, I is second moment of area.

Fatigue life is reduced by stress concentrations; holes, sharp corners, and corrosion pits act as stress raisers and require inspection per structural repair manual.

Composite structures: carbon-fibre reinforced polymer is anisotropic; impact damage may cause internal delamination not visible externally, requiring tap testing or NDT.

Airframe zoning (ATA 100) divides the aircraft into zones for maintenance and inspection; typical zones include fuselage, wings, empennage, landing gear, and powerplant.

Hydraulic system pressure is typically 3000 psi (20684 kPa) in modern transport aircraft; pressure is regulated by a system relief valve and engine-driven pump case drain.

Hydraulic fluid types: MIL-H-5606 (red, mineral-based) and Skydrol (phosphate ester, purple, fire-resistant); they must not be mixed; seals differ (natural rubber vs butyl).

Pascal's law: pressure applied to a confined fluid is transmitted equally in all directions; Force = Pressure × Area (F = P × A).

Pneumatic system: engine bleed air is used for air-conditioning, pressurisation, and anti-icing; typical bleed pressure is 30–50 psi with temperature up to 250°C after precooler.

Fuel system: fuel is stored in wing and centre tanks; vent system prevents over/under pressure; fuel quantity indicating uses capacitance probes or float switches.

Ice protection: thermal anti-ice uses hot bleed air on wing leading edges and engine inlets; de-ice boots use pneumatic inflation for propeller and airframe de-icing.

Rain protection: windshield wipers, chemical rain repellent, and heated windshields; windshield heating prevents ice and mist and is controlled by a windshield heat controller.

Hydraulic reservoir pressurisation prevents pump cavitation at altitude; pressurisation is typically from engine bleed air or a dedicated nitrogen bottle.

AC electrical power: 115 V AC, 400 Hz, three-phase star or delta; generated by integrated drive generators (IDG) or variable frequency generators (VFG).

DC power: 28 V DC from transformer-rectifier units (TRU) or batteries; battery capacity is rated in ampere-hours (Ah) and cold cranking amps.

Generator control unit (GCU) regulates voltage, protects against over/under voltage, overfrequency, and disconnects generator from bus.

Pitot-static instruments: altimeter, airspeed indicator, and vertical speed indicator; static port blockage causes altimeter to freeze and airspeed to behave as altimeter.

Gyroscopic instruments: attitude indicator (vertical gyro), heading indicator (directional gyro), and turn coordinator; powered by vacuum or electrically.

Avionics buses: ARINC 429 is a point-to-point digital bus; ARINC 629 and Ethernet are used on modern aircraft; CAN bus is used for some systems.

Electrical bonding and shielding: bonding minimizes static discharge and provides return path; shielding protects against electromagnetic interference (EMI).

Primary flight controls: ailerons (roll), elevators (pitch), rudder (yaw); secondary controls: flaps, slats, spoilers, trim tabs.

Fly-by-wire (FBW) replaces mechanical linkages with electrical signals and hydraulic actuators; redundancy is provided by multiple computers and power sources.

Landing gear: oleo-pneumatic shock strut absorbs landing loads; servicing requires correct nitrogen pressure and oil level; torque links maintain wheel alignment.

Landing gear retraction: hydraulic or electric actuation; uplocks and downlocks secure gear; squat switches prevent retraction on ground.

Cabin pressurisation: outflow valve controls cabin altitude; typical maximum cabin altitude 8000 ft; differential pressure limit (e.g., 8.6 psi) must not be exceeded.

Cabin systems: emergency oxygen from chemical generators or bottles; passenger service units (PSU) include reading lights, air vents, and oxygen masks.

Flight control surface balancing: mass balance prevents flutter; leading edge balance weights or horn balances are used; any repair affecting balance requires rebalancing.

Engine mount: attaches engine to airframe; must absorb thrust, torque, and gyroscopic loads; inspection for cracks and loose bolts is critical.

Firewall and fire detection: engine fire zones are separated by firewalls; fire detection uses thermocouples or continuous loop sensors; fire extinguishing uses Halon or inert gas.

Propeller: converts engine power to thrust; blade angle measured from plane of rotation; feathering sets blade angle to zero thrust; reverse pitch produces reverse thrust.

Propeller balance: static and dynamic balance reduce vibration; track and balance using vibration sensors and blade tracking.

Constant-speed propeller: governor controls blade angle to maintain selected RPM; oil pressure or centrifugal force changes blade angle.

Engine exhaust: exhaust systems must be free of leaks; cracks can cause carbon monoxide ingress into cabin; inspection for soot stains indicates leaks.

Powerplant controls: throttle, mixture, propeller pitch; rigging ensures full travel and correct stops; cable tension and rod-end adjustment per maintenance manual.

Maintenance documentation: logbooks, work orders, and release to service; all maintenance must be recorded and signed by authorised personnel.

Inspection types: pre-flight, daily, weekly, and periodic (A, B, C, D checks); A check every 500–800 flight hours, C check every 12–18 months, D check every 5–6 years.

NDT methods: visual, dye penetrant, magnetic particle, eddy current, ultrasonic, and radiography; each has specific applications and limitations.

Corrosion control: remove corrosion by blending within limits; apply protective coatings; regular washing and inspection for corrosion-prone areas.

Torque procedures: use calibrated torque wrench; torque values from maintenance manual; apply torque in sequence for multi-bolt joints.

Airworthiness directives (ADs) are mandatory; service bulletins are recommended unless incorporated by AD; compliance records must be kept.

Weight and balance: empty weight and CG must be within limits; calculations use moments (weight × arm); exceeding limits affects performance and stability.