CAA NZ CPL Aircraft Technical Knowledge cheat sheet

In steady level flight lift equals weight and thrust equals drag; lift L = ½ρV²SCL, so for a given weight CL must increase as speed falls.

Stall occurs at the critical angle of attack, not at a fixed speed; Vs = √(2W/(ρSCLmax)) and increases with weight and load factor.

Induced drag is proportional to CL²/(ρV²S) and dominates at low speed; parasite drag is proportional to ρV² and dominates at high speed.

In a level coordinated turn load factor n = 1/cos φ; stall speed increases by √n (at 60° bank n = 2, so Vs increases about 41%).

Ailerons produce roll and adverse yaw because the wing with the up-deflected aileron has higher induced drag; rudder coordinates the turn.

Dihedral provides lateral static stability: a sideslip gives the lower wing a higher effective angle of attack and rolls the aircraft away from the slip.

Flaps increase CLmax and drag; select within VFE, expect a pitch change, and observe any go-around retraction limit.

Elevator controls pitch; a trim tab generates a small hinge moment that holds the control surface without continuous pilot force.

Positive static stability tends to return an aircraft to its original attitude; positive dynamic stability means oscillations damp out over time.

Semi-monocoque construction uses stressed skin to carry tension and shear, with frames, formers and stringers stiffening the skin and preventing buckling.

Spars carry the main wing bending loads; ribs hold the airfoil shape and transfer loads between skin and spars.

Safe-life components are retired at a calculated life; fail-safe design provides alternate load paths so a crack or failure is tolerable until inspection.

Damage tolerance requires inspection intervals that ensure a crack cannot grow to critical size between checks.

Honeycomb sandwich panels use face sheets for tension/compression and a core for shear; debonding or core damage can sharply reduce strength.

Common aluminium corrosion forms are pitting, galvanic, intergranular and exfoliation; exfoliation appears as lifted layers at rivet rows and edges.

Stop-drill the ends of a crack only as a temporary measure and have the structure assessed; do not stop-drill primary structure without approval.

Control surfaces are mass-balanced to prevent flutter; a free or under-balanced surface can flutter and fail rapidly.

Pressurized fuselage hoop stress is σ = pr/t and longitudinal stress is approximately pr/(2t); fatigue cracks often start at cutouts and fastener holes.

A four-stroke piston engine completes intake, compression, power and exhaust in two crankshaft revolutions; one power stroke per cylinder per two revolutions.

Brake power is the useful shaft power; friction and pumping losses make indicated power higher than brake power.

Engine power depends on air mass flow, fuel flow and combustion efficiency; leaning to peak EGT gives approximately stoichiometric mixture.

Detonation is uncontrolled rapid combustion after normal ignition; pre-ignition is ignition before the spark. Both raise CHT and can damage pistons.

High manifold pressure, low RPM, high inlet temperature and lean mixture increase detonation risk; obey POH power and mixture limits.

A constant-speed propeller governor uses flyweights and oil pressure to change blade angle; loss of oil pressure usually drives the propeller to fine pitch (high RPM).

Propeller efficiency = thrust power / shaft power; geometric pitch minus effective pitch equals slip.

Magneto check: with the engine at run-up RPM, select each magneto in turn; typical maximum drop is 150 RPM and maximum difference 50 RPM, but use the aircraft POH.

Carburettor ice can form at outside air temperatures from about -10°C to +25°C with high humidity; apply carb heat and expect rough running as ice melts.

Fuel system: tank selector, sump drains and boost pumps; unusable fuel cannot be safely used in flight and is included in empty weight.

Fuel drains are checked before flight for water and sediment; water in avgas is detected by colour and cloudiness and must be drained.

Wet-sump engines store oil in the crankcase; dry-sump engines use a separate oil tank and return oil through a cooler.

Electrical: the battery supplies power for starting and emergency; the alternator/generator charges the battery and carries the bus load after start.

Ammeter shows charge/discharge current; a loadmeter shows alternator output as a percentage or current; circuit breakers protect wiring.

Hydraulic pressure = force / area (Pascal's law); a relief valve protects the system and an accumulator damps pressure pulses and supplies reserve.

Vacuum gyros are driven by engine-driven vacuum/pressure pumps; typical suction gauge range is 4.5-5.5 inHg; loss of suction makes attitude and heading indicators unreliable.

Ice protection: pitot heat, static heat, carburettor heat, prop anti-ice and pneumatic de-ice boots; boots break ice by inflation, not by heating.

Fire needs fuel, oxygen and heat; fire extinguishers remove heat or oxygen; fuel and electrical shutoffs isolate the source.

The ASI measures dynamic pressure from the pitot and static sources; it indicates indicated airspeed and is subject to position, instrument, compressibility and density errors.

The altimeter is a barometer set to the local pressure datum; 1 inHg change is about 1000 ft near sea level, and turning the subscale affects the indication directly.

The VSI is a rate-of-change instrument with a calibrated leak; it lags in climbs and descents and should be read after the indication stabilizes.

Vacuum-driven attitude and heading indicators rely on gyroscopic rigidity; the heading indicator drifts and must be realigned with the magnetic compass.

The turn coordinator shows rate of turn and roll; a standard-rate turn is 3° per second, 180° in one minute, 360° in two minutes.

The magnetic compass has variation (true vs magnetic), deviation (compass error) and dip; acceleration and turning errors are largest near the poles.

VOR, ILS and NDB provide navigation guidance; the CDI shows course deviation and a TO/FROM flag; an HSI combines heading and course.

GPS accuracy depends on satellite geometry and RAIM; WAAS improves integrity and accuracy; ADS-B transmits position and altitude.

Glass cockpit PFD/MFD systems use AHRS and air data computers; standby instruments are provided for loss of electrical or pitot-static power.

Moment = weight × arm; CG = total moment / total weight; a forward CG is ahead of the datum and an aft CG is behind it.

Empty weight includes unusable fuel and full oil; useful load = maximum takeoff weight - empty weight; payload is useful load minus fuel.

CG must remain within limits for all loading and fuel states; forward CG raises stall speed and landing distance, aft CG reduces static stability.

Density altitude = pressure altitude + 120 × (OAT - ISA temperature at that altitude) approximately; ISA sea level is 15°C and 1013.25 hPa.

Takeoff and landing distances increase with density altitude, weight, tailwind, uphill slope, wet or contaminated runway, and reduced flap setting.

Best angle of climb Vx gives maximum height gain per horizontal distance; best rate of climb Vy gives maximum height gain per time.

Va (manoeuvring speed) decreases with weight; it is the speed above which full control deflection can overstress the structure.

Fuel planning includes taxi, trip, contingency, alternate and final reserve; fuel weight reduces payload or increases takeoff weight.

Load sheets check max zero-fuel weight, max landing/takeoff weight, floor loading and seat limits.