Brunei DCA CPL AGK - Airframe, Systems & Power Plant cheat sheet

Semi-monocoque construction: skin carries most shear and tension loads, longitudinal stringers and frames stabilise the skin against buckling and carry concentrated loads.

Wing spar caps take bending loads (tension upper surface, compression lower surface); spar webs carry shear; ribs maintain aerofoil shape and transfer load to spars.

Empennage: horizontal stabiliser provides longitudinal static stability (negative gradient of pitching moment with angle of attack); vertical fin provides directional stability.

Primary controls are ailerons, elevator and rudder; secondary controls are flaps, slats, spoilers, trim tabs and leading-edge devices.

Differential aileron travel (up aileron deflects more than down) reduces adverse yaw by equalising induced drag between the down-going and up-going wing.

Mass balance weights ahead of the hinge line prevent control-surface flutter by keeping the surface centre of gravity at or forward of the hinge.

A fixed tab moves with the surface and alters trim; a servo tab moves opposite and aerodynamically drives the surface, reducing pilot effort.

Fail-safe design uses redundant load paths and crack-stopper straps so a single failure does not cause structural collapse.

Pascal's law: pressure applied to a confined fluid is transmitted undiminished; force = pressure × piston area, so a larger actuator area gives greater force at lower travel.

Reservoirs are pressurised (engine bleed or hydraulic pressure) to prevent pump cavitation at altitude and to supply positive head to the pump inlet.

Engine-driven pumps are constant-delivery; system pressure is regulated by an unloading valve (pressure regulator) that returns excess flow to the reservoir.

Accumulators (nitrogen pre-charged) store energy for emergency operation, damp pressure surges and maintain pressure during pump transients; precharge is checked with the system unpressurised.

Relief valve protects against overpressure; check valve enforces one-way flow; selector valve directs flow to the chosen actuator; restrictor/flow-control valve limits actuator speed.

Seals: O-rings and dynamic seals at actuator rods; internal leakage causes slow actuator drift, external leakage causes quantity loss and pressure drop.

Indications: system pressure gauge (low pressure warning switch), reservoir quantity, pump low-pressure caution; a rising temperature may indicate excessive internal leakage.

Hydraulic fluid is incompressible; air in the system causes spongy response, so systems are bled after maintenance.

Bleed air sources: engine compressor stage bleed (HP/LP), APU load compressor, or ground cart; bleed air is used for air-conditioning, pressurisation and anti-ice.

Air-cycle machine: bleed air passes through a primary heat exchanger, compressor, secondary heat exchanger, then expansion through a turbine that cools the air and drives the compressor.

Pressurisation is controlled by outflow valves; cabin altitude is a function of the selected schedule and the valve opening, not of inflow alone.

Cabin differential pressure = cabin pressure − ambient pressure; it is limited by a relief valve (typically around 8–9 psi in transport aircraft) and structural design.

Rate of change of cabin altitude is limited by the controller (climb and descent rates); a rapid decompression is indicated by cabin altitude warning and pressure differential loss.

Pneumatic system indications: bleed pressure, duct temperature, valve position; over-temperature and over-pressure sensors close the bleed valve automatically.

Water separator removes moisture downstream of the turbine to prevent fog and ice in the cabin distribution ducts.

Pneumatic system leaks are detected by duct pressure loss, overheat loops and visible tell-tale; isolation valves allow a failed branch to be shut off.

DC generation: engine-driven DC generator or alternator with rectifier; voltage regulator holds output constant; reverse-current relay prevents battery discharge through the generator.

AC generation: alternator with rotating field; constant frequency is maintained by a CSD (constant-speed drive) or by variable-frequency (VF) generation with fixed-electronic conversion.

AC power is distributed at 115 V 400 Hz (or 115 V variable frequency); transformer-rectifier units (TRUs) supply 28 V DC from AC buses.

Bus tie and contactor logic determine which source feeds which bus; a generator trip removes the source and the bus transfers to another source automatically.

Batteries: lead-acid (vented, electrolyte level check) and NiCd (higher current, memory/thermal runaway risk); battery supplies essential DC during generator failure and for APU/engine start.

Circuit protection: fuses (one-shot, thermal) and circuit breakers (resettable, thermal or magnetic); a popped breaker must not be reset unless the fault is cleared.

Bonding and shielding: aircraft structure forms the earth return; bonding straps maintain low resistance and RF shielding protects against lightning and interference.

Indications: generator voltage/current, bus voltage, frequency, loadmeter; a low-voltage or over-voltage condition trips the generator offline.

Shock strut: oleo (air/oil) type; nitrogen precharge supports the static load and oil metering through an orifice absorbs landing energy.

Main gear supports the aircraft weight; nose gear carries a small fraction (typically 8–15%) and provides steering; torque links maintain wheel alignment and transmit braking torque.

Brake systems: independent (each pedal its own brake) or power brake with a metering valve; hydraulic pressure applied to brake pistons clamps the discs.

Anti-skid: wheel speed transducers detect a locked wheel and modulate brake pressure through a control valve to maintain optimum slip (maximum friction near 10–20% slip).

Wheel construction: tubeless tyre on a split-hub wheel; tyre markings give ply rating, load rating and speed rating; under-inflation causes sidewall flexing and heat.

Parking brake is a mechanical or accumulator-held brake; it must not be set with hot brakes because differential cooling can warp discs.

Brake temperature indication warns of overheating; a fuse plug in the wheel melts at high temperature to release tyre pressure before a blow-out.

Retraction: gear up-locks, down-locks and squat switches prevent retraction on the ground; a warning horn sounds if gear is not down with power reduced.

Fuel tanks: integral (wet wing) tanks use the wing structure as the tank; bladder and rigid tanks are alternatives; venting prevents tank collapse and allows fuel transfer.

Fuel pumps: engine-driven low-pressure pump plus electric boost pumps in the tanks; boost pumps supply positive pressure to prevent vapour lock at altitude.

Fuel quantity is measured by capacitance probes (dielectric change with fuel level) or float sensors; fuel flow is measured by a flowmeter in the line to the engine.

Fuel management: crossfeed valves allow either engine to be fed from either tank; balancing is achieved by selective tank-to-engine routing, not by gravity alone.

Fuel jettison (if fitted) uses dump valves and must be terminated at a safe altitude and with a minimum landing fuel.

Contamination: water settles at the lowest point and is drained at sump drains; microbial growth appears as a dark sludge; fuel samples are taken before flight.

Fuel grade and additives: AVGAS 100LL for piston engines, Jet A-1 for turbines; never mix; FSII (icing inhibitor) and anti-static additives are specified in the fuel specification.

Unusable fuel is the quantity that cannot be safely supplied in all attitudes; fuel quantity indications must be verified against dipsticks or totaliser before flight.

Pneumatic de-ice boots inflate cyclically on the leading edge and shed ice by cracking it; thermal anti-ice uses engine bleed air through piccolo tubes.

Electro-thermal anti-ice is used for propellers, pitot heads, static ports and windshield; pitot heat must be on in visible moisture or icing conditions.

Windshield rain protection: wipers, rain repellent, or heated windshield; windshield heat also prevents ice and maintains impact strength.

Fire detection: engine fire loops (continuous resistance or spot detectors) respond to overheat; a fire warning requires the correct drill: close fuel, bleed, and electrical supply, then discharge the extinguisher.

Fire extinguishing agents: Halon (or replacement agents) for engines and cabins; two-shot bottles give a second discharge after the first is exhausted.

Cargo and cabin smoke detectors are photoelectric or ionisation types; a smoke warning requires isolation of electrical power to the affected area.

Oxygen systems: gaseous (cylinders) or chemical (sodium chlorate candles); crew masks are demand type, passenger masks drop automatically from the mask container.

Oxygen system checks: pressure/quantity, regulator operation, mask seal; oxygen must not be used near grease or oil because of combustion risk.

Four-stroke cycle: induction, compression, power, exhaust; in a horizontally opposed engine the crankshaft makes two revolutions per complete cycle.

Firing order and crankshaft layout determine smoothness; the camshaft runs at half crankshaft speed, and valve clearance is set with the engine cold.

Induction: normally aspirated or turbocharged; a turbocharger uses exhaust gas energy to drive a compressor, with a wastegate controlling boost.

Ignition: two magnetos, each firing one plug per cylinder; magneto timing is set before top dead centre (typically 20–25° BTDC) and the engine will run on one magneto.

Carburettor: float chamber, venturi and throttle; mixture is leaned with altitude; carburettor icing occurs at 0–20 °C with high humidity and is prevented by carb heat.

Fuel injection: metered fuel delivered to each cylinder; advantages are better distribution and immunity to carburettor icing (but throttle icing can still occur).

Lubrication: dry-sump system with pressure pump, scavenge pump, oil cooler and filter; oil pressure indicates pump and bearing condition, oil temperature indicates cooling.

Cooling: air-cooled cylinders with cooling fins and baffles; cylinder head temperature (CHT) and oil temperature are the primary limits.

Aerofoil sections produce thrust; blade angle is the angle between the chord and the plane of rotation; angle of attack is the angle between the chord and the relative airflow.

Geometric pitch is the theoretical forward distance per revolution; effective pitch is less because of slip; slip is the difference between geometric and effective pitch.

Constant-speed unit: a governor with flyweights senses RPM and ports oil to or from the propeller hub to change blade angle and hold selected RPM.

Feathering: blades rotated to approximately 90° (edge-on to the airflow) to minimise drag after engine failure; feathering is prevented below a low-RPM lock.

Reverse thrust (turboprop) rotates blades past the fine pitch stop to a negative angle; it is used for ground deceleration only.

Synchronising matches engine/propeller RPM to reduce beat noise; synchrophasing sets a fixed blade phase relationship between propellers.

Propeller icing: ice on the blade destroys aerofoil efficiency and causes vibration; protection is by electro-thermal boots or fluid anti-ice.

Propeller balance and track: blade tracking checks tip path; dynamic balancing reduces vibration; a nick or bend beyond limits requires blade replacement.

Airflow path: intake, compressor (axial or centrifugal), diffuser, combustion chamber, turbine, exhaust; the turbine drives the compressor, and the remaining energy produces thrust.

Compressor surge is a reversal of flow caused by excessive angle of attack on the blades; it is prevented by bleed valves, variable inlet guide vanes and careful throttle handling.

Combustion: fuel is atomised by nozzles, mixed with air and burned continuously; only about 25% of the air takes part in combustion, the rest cools the flame tube.

Turbine blades are cooled by compressor bleed air and use nickel-based alloys; turbine gas temperature (TGT/EGT) is the limiting parameter.

Lubrication: dry-sump system with pressure and scavenge pumps; oil cools and lubricates bearings; oil pressure loss requires immediate engine shutdown.

Starting: starter motor (air or electric) rotates the compressor, ignition is switched on, fuel is introduced, and the engine accelerates to idle; a hot or hung start must be aborted.

Thrust augmentation: afterburner (reheat) adds fuel downstream of the turbine; water/methanol injection increases mass flow for short periods.

Engine indications: N1 (fan/LP compressor), N2 (HP compressor), EGT/TGT, fuel flow, oil pressure and temperature; exceedances are recorded and require inspection.

Semi-monocoque construction: skin carries most shear and tension loads, longitudinal stringers and frames stabilise the skin against buckling and carry concentrated loads.

Wing spar caps take bending loads (tension upper surface, compression lower surface); spar webs carry shear; ribs maintain aerofoil shape and transfer load to spars.

Empennage: horizontal stabiliser provides longitudinal static stability (negative gradient of pitching moment with angle of attack); vertical fin provides directional stability.

Primary controls are ailerons, elevator and rudder; secondary controls are flaps, slats, spoilers, trim tabs and leading-edge devices.

Differential aileron travel (up aileron deflects more than down) reduces adverse yaw by equalising induced drag between the down-going and up-going wing.

Mass balance weights ahead of the hinge line prevent control-surface flutter by keeping the surface centre of gravity at or forward of the hinge.

A fixed tab moves with the surface and alters trim; a servo tab moves opposite and aerodynamically drives the surface, reducing pilot effort.

Fail-safe design uses redundant load paths and crack-stopper straps so a single failure does not cause structural collapse.

Pascal's law: pressure applied to a confined fluid is transmitted undiminished; force = pressure × piston area, so a larger actuator area gives greater force at lower travel.

Reservoirs are pressurised (engine bleed or hydraulic pressure) to prevent pump cavitation at altitude and to supply positive head to the pump inlet.

Engine-driven pumps are constant-delivery; system pressure is regulated by an unloading valve (pressure regulator) that returns excess flow to the reservoir.

Accumulators (nitrogen pre-charged) store energy for emergency operation, damp pressure surges and maintain pressure during pump transients; precharge is checked with the system unpressurised.

Relief valve protects against overpressure; check valve enforces one-way flow; selector valve directs flow to the chosen actuator; restrictor/flow-control valve limits actuator speed.

Seals: O-rings and dynamic seals at actuator rods; internal leakage causes slow actuator drift, external leakage causes quantity loss and pressure drop.

Indications: system pressure gauge (low pressure warning switch), reservoir quantity, pump low-pressure caution; a rising temperature may indicate excessive internal leakage.

Hydraulic fluid is incompressible; air in the system causes spongy response, so systems are bled after maintenance.

Bleed air sources: engine compressor stage bleed (HP/LP), APU load compressor, or ground cart; bleed air is used for air-conditioning, pressurisation and anti-ice.

Air-cycle machine: bleed air passes through a primary heat exchanger, compressor, secondary heat exchanger, then expansion through a turbine that cools the air and drives the compressor.

Pressurisation is controlled by outflow valves; cabin altitude is a function of the selected schedule and the valve opening, not of inflow alone.

Cabin differential pressure = cabin pressure − ambient pressure; it is limited by a relief valve (typically around 8–9 psi in transport aircraft) and structural design.

Rate of change of cabin altitude is limited by the controller (climb and descent rates); a rapid decompression is indicated by cabin altitude warning and pressure differential loss.

Pneumatic system indications: bleed pressure, duct temperature, valve position; over-temperature and over-pressure sensors close the bleed valve automatically.

Water separator removes moisture downstream of the turbine to prevent fog and ice in the cabin distribution ducts.

Pneumatic system leaks are detected by duct pressure loss, overheat loops and visible tell-tale; isolation valves allow a failed branch to be shut off.

DC generation: engine-driven DC generator or alternator with rectifier; voltage regulator holds output constant; reverse-current relay prevents battery discharge through the generator.

AC generation: alternator with rotating field; constant frequency is maintained by a CSD (constant-speed drive) or by variable-frequency (VF) generation with fixed-electronic conversion.

AC power is distributed at 115 V 400 Hz (or 115 V variable frequency); transformer-rectifier units (TRUs) supply 28 V DC from AC buses.

Bus tie and contactor logic determine which source feeds which bus; a generator trip removes the source and the bus transfers to another source automatically.

Batteries: lead-acid (vented, electrolyte level check) and NiCd (higher current, memory/thermal runaway risk); battery supplies essential DC during generator failure and for APU/engine start.

Circuit protection: fuses (one-shot, thermal) and circuit breakers (resettable, thermal or magnetic); a popped breaker must not be reset unless the fault is cleared.

Bonding and shielding: aircraft structure forms the earth return; bonding straps maintain low resistance and RF shielding protects against lightning and interference.

Indications: generator voltage/current, bus voltage, frequency, loadmeter; a low-voltage or over-voltage condition trips the generator offline.

Shock strut: oleo (air/oil) type; nitrogen precharge supports the static load and oil metering through an orifice absorbs landing energy.

Main gear supports the aircraft weight; nose gear carries a small fraction (typically 8–15%) and provides steering; torque links maintain wheel alignment and transmit braking torque.

Brake systems: independent (each pedal its own brake) or power brake with a metering valve; hydraulic pressure applied to brake pistons clamps the discs.

Anti-skid: wheel speed transducers detect a locked wheel and modulate brake pressure through a control valve to maintain optimum slip (maximum friction near 10–20% slip).

Wheel construction: tubeless tyre on a split-hub wheel; tyre markings give ply rating, load rating and speed rating; under-inflation causes sidewall flexing and heat.

Parking brake is a mechanical or accumulator-held brake; it must not be set with hot brakes because differential cooling can warp discs.

Brake temperature indication warns of overheating; a fuse plug in the wheel melts at high temperature to release tyre pressure before a blow-out.

Retraction: gear up-locks, down-locks and squat switches prevent retraction on the ground; a warning horn sounds if gear is not down with power reduced.

Fuel tanks: integral (wet wing) tanks use the wing structure as the tank; bladder and rigid tanks are alternatives; venting prevents tank collapse and allows fuel transfer.

Fuel pumps: engine-driven low-pressure pump plus electric boost pumps in the tanks; boost pumps supply positive pressure to prevent vapour lock at altitude.

Fuel quantity is measured by capacitance probes (dielectric change with fuel level) or float sensors; fuel flow is measured by a flowmeter in the line to the engine.

Fuel management: crossfeed valves allow either engine to be fed from either tank; balancing is achieved by selective tank-to-engine routing, not by gravity alone.

Fuel jettison (if fitted) uses dump valves and must be terminated at a safe altitude and with a minimum landing fuel.

Contamination: water settles at the lowest point and is drained at sump drains; microbial growth appears as a dark sludge; fuel samples are taken before flight.

Fuel grade and additives: AVGAS 100LL for piston engines, Jet A-1 for turbines; never mix; FSII (icing inhibitor) and anti-static additives are specified in the fuel specification.

Unusable fuel is the quantity that cannot be safely supplied in all attitudes; fuel quantity indications must be verified against dipsticks or totaliser before flight.

Pneumatic de-ice boots inflate cyclically on the leading edge and shed ice by cracking it; thermal anti-ice uses engine bleed air through piccolo tubes.

Electro-thermal anti-ice is used for propellers, pitot heads, static ports and windshield; pitot heat must be on in visible moisture or icing conditions.

Windshield rain protection: wipers, rain repellent, or heated windshield; windshield heat also prevents ice and maintains impact strength.

Fire detection: engine fire loops (continuous resistance or spot detectors) respond to overheat; a fire warning requires the correct drill: close fuel, bleed, and electrical supply, then discharge the extinguisher.

Fire extinguishing agents: Halon (or replacement agents) for engines and cabins; two-shot bottles give a second discharge after the first is exhausted.

Cargo and cabin smoke detectors are photoelectric or ionisation types; a smoke warning requires isolation of electrical power to the affected area.

Oxygen systems: gaseous (cylinders) or chemical (sodium chlorate candles); crew masks are demand type, passenger masks drop automatically from the mask container.

Oxygen system checks: pressure/quantity, regulator operation, mask seal; oxygen must not be used near grease or oil because of combustion risk.

Four-stroke cycle: induction, compression, power, exhaust; in a horizontally opposed engine the crankshaft makes two revolutions per complete cycle.

Firing order and crankshaft layout determine smoothness; the camshaft runs at half crankshaft speed, and valve clearance is set with the engine cold.

Induction: normally aspirated or turbocharged; a turbocharger uses exhaust gas energy to drive a compressor, with a wastegate controlling boost.

Ignition: two magnetos, each firing one plug per cylinder; magneto timing is set before top dead centre (typically 20–25° BTDC) and the engine will run on one magneto.

Carburettor: float chamber, venturi and throttle; mixture is leaned with altitude; carburettor icing occurs at 0–20 °C with high humidity and is prevented by carb heat.

Fuel injection: metered fuel delivered to each cylinder; advantages are better distribution and immunity to carburettor icing (but throttle icing can still occur).

Lubrication: dry-sump system with pressure pump, scavenge pump, oil cooler and filter; oil pressure indicates pump and bearing condition, oil temperature indicates cooling.

Cooling: air-cooled cylinders with cooling fins and baffles; cylinder head temperature (CHT) and oil temperature are the primary limits.

Aerofoil sections produce thrust; blade angle is the angle between the chord and the plane of rotation; angle of attack is the angle between the chord and the relative airflow.

Geometric pitch is the theoretical forward distance per revolution; effective pitch is less because of slip; slip is the difference between geometric and effective pitch.

Constant-speed unit: a governor with flyweights senses RPM and ports oil to or from the propeller hub to change blade angle and hold selected RPM.

Feathering: blades rotated to approximately 90° (edge-on to the airflow) to minimise drag after engine failure; feathering is prevented below a low-RPM lock.

Reverse thrust (turboprop) rotates blades past the fine pitch stop to a negative angle; it is used for ground deceleration only.

Synchronising matches engine/propeller RPM to reduce beat noise; synchrophasing sets a fixed blade phase relationship between propellers.

Propeller icing: ice on the blade destroys aerofoil efficiency and causes vibration; protection is by electro-thermal boots or fluid anti-ice.

Propeller balance and track: blade tracking checks tip path; dynamic balancing reduces vibration; a nick or bend beyond limits requires blade replacement.

Airflow path: intake, compressor (axial or centrifugal), diffuser, combustion chamber, turbine, exhaust; the turbine drives the compressor, and the remaining energy produces thrust.

Compressor surge is a reversal of flow caused by excessive angle of attack on the blades; it is prevented by bleed valves, variable inlet guide vanes and careful throttle handling.

Combustion: fuel is atomised by nozzles, mixed with air and burned continuously; only about 25% of the air takes part in combustion, the rest cools the flame tube.

Turbine blades are cooled by compressor bleed air and use nickel-based alloys; turbine gas temperature (TGT/EGT) is the limiting parameter.

Lubrication: dry-sump system with pressure and scavenge pumps; oil cools and lubricates bearings; oil pressure loss requires immediate engine shutdown.

Starting: starter motor (air or electric) rotates the compressor, ignition is switched on, fuel is introduced, and the engine accelerates to idle; a hot or hung start must be aborted.

Thrust augmentation: afterburner (reheat) adds fuel downstream of the turbine; water/methanol injection increases mass flow for short periods.

Engine indications: N1 (fan/LP compressor), N2 (HP compressor), EGT/TGT, fuel flow, oil pressure and temperature; exceedances are recorded and require inspection.