NCAA PPL (Helicopter) Theory Exam flashcards

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

Special VFR clearance

An ATC authorisation allowing flight in controlled airspace below VFR minima, subject to the State's published conditions and pilot request.

Final reserve fuel helicopter

Fuel required to fly for 30 minutes at cruise speed after the last planned landing; reduced to 20 minutes for approved helicopter emergency medical service flights.

Lead-lag hinge

A hinge allowing the blade to move in the plane of rotation, relieving Coriolis forces; its damper prevents ground resonance and blade oscillation.

Freewheeling unit

A sprag clutch that disconnects the engine from the rotor when engine power falls below rotor speed, allowing autorotation.

Ground resonance

A destructive vibration occurring on the ground when blade lead-lag frequency matches airframe natural frequency; correct action is immediate liftoff or shutdown.

Mast bumping

Contact between a blade grip and the mast on a semi-rigid rotor during low-G flapping; prevented by limiting cyclic input and avoiding pushovers.

Density altitude formula

Pressure altitude plus 120 times the difference between outside air temperature and ISA temperature at that level; higher values reduce performance.

IGE versus OGE hover

In-ground-effect hover requires less power because the rotor downwash is restricted; out-of-ground-effect hover requires more power and has a lower ceiling.

Centre of gravity limits

The forward and aft range within which the loaded helicopter's CG must lie; exceeding either limit reduces control authority and may be unsafe.

Time of useful consciousness

The period after loss of pressurisation during which a pilot can still act effectively; about 3-5 minutes at 25 000 ft.

Somatogravic illusion

A false sensation of climbing during acceleration, caused by the vestibular system sensing linear acceleration as pitch change.

Carbon monoxide poisoning

Exhaust gas leakage causing headache, confusion and cherry-red skin; treated with 100% oxygen and immediate landing.

Yerkes-Dodson law

Performance peaks at moderate arousal; too little arousal causes complacency, too much narrows attention and increases error rates.

QNH versus QFE

QNH is pressure reduced to sea level, giving altitude on the altimeter; QFE is pressure at the aerodrome, giving height above the aerodrome.

Carburettor icing range

Icing can occur at ambient temperatures between about -7 °C and +21 °C with high humidity; use carburettor heat as required.

Microburst

A concentrated downdraft causing sudden headwind then tailwind shear near the ground; avoid thunderstorms by at least 20 nautical miles.

1 in 60 rule

A one-degree tracking error produces one nautical mile off track after 60 nautical miles; used for mental drift and closing-angle calculations.

Track error formula

Track error in degrees equals distance off track divided by distance flown, multiplied by 60; closing angle uses distance to go.

Transition altitude

The altitude below which QNH is set and altitude is flown; above it, 1013.25 hPa is set and flight levels are used.

Autorotation entry

Lower collective immediately to maintain rotor RPM, select a landing area, flare at about 50 ft, and cushion the landing with collective.

Tail rotor failure at speed

Maintain forward speed to keep the tail steady, reduce power gently, and fly to a suitable landing area; at low speed, close throttle and land.

MAYDAY versus PAN-PAN

MAYDAY, spoken three times, signals distress and immediate danger; PAN-PAN, spoken three times, signals urgency without immediate danger.

Translational lift

Improved rotor efficiency at about 15-20 knots effective airspeed, when the rotor leaves its own downwash and requires less power.

Dissymmetry of lift

The advancing blade sees higher airspeed than the retreating blade; flapping and cyclic feathering equalise lift across the disc.

Retreating blade stall

Stall on the retreating blade at high speed, high mass, low RPM or high density altitude; symptoms include pitch-up and vibration.

Vortex ring state

Settling with power during descent of 300-800 ft/min at low airspeed with high power; recover with forward cyclic and collective reduction.

Effective translational lift

The airspeed at which the rotor fully escapes its downwash, improving hover performance and reducing power required, typically 15-20 knots.

Readback requirement

Clearances, runway assignments, altimeter settings and hold-short instructions must be read back to the controller.

Emergency frequency

121.5 MHz is the international aeronautical emergency frequency, used for distress calls and homing by rescue services.

Wilco and roger

Wilco means will comply with the instruction; roger means the transmission was received, without implying compliance.

Lost communication squawk

Set transponder code 7600, continue under VFR, land at the nearest suitable aerodrome, and report to ATC after landing.

Position report contents

Aircraft identification, position, time, altitude or flight level, next position and estimated time over it.