FAA commercial helicopter pilot theory foundations key terms

Unequal aerodynamic loading associated with different relative airflow on advancing and retreating rotor sides in the stated condition, if uncompensated.

Blade motion above and below the defined rotor reference, accommodated by the actual hub design and distinguished from pitch change and lead-lag.

Blade movement in the rotor plane relative to its reference position, distinguished from vertical flapping or rotation about the feathering axis.

The upward rotor-blade geometry resulting from the balance of aerodynamic and centrifugal effects in the actual condition, not an arbitrary rigging angle.

Rotor operation driven by the relevant airflow rather than engine torque, requiring the actual aircraft procedure for any real maneuver.

The control function changing main-rotor blade pitch together in the defined system, distinguished from azimuth-dependent cyclic variation.

Variation of blade pitch with rotor azimuth to control rotor behavior, interpreted through the actual phase and control architecture.

An overrun mechanism permitting the rotor and relevant engine input to rotate at different speeds as designed rather than rigidly locking them together.

The rotating/nonrotating interface transmitting the defined collective and cyclic control inputs through the actual links to rotor blade pitch mechanisms.

A mechanism combining defined control commands to manage their interactions, not an independent guarantee of correct trim or control margin.

A linkage relating power-control movement to collective movement in the defined installation, distinguished from closed-loop speed feedback that corrects actual RPM error.

A control function using the relevant feedback to regulate the selected speed or parameter within its actual authority and limits.

A performance boundary for the specified hover condition, weight and atmosphere, not a universal permission to depart any confined or elevated site.

The location found from total moment divided by total weight in a consistent datum system, requiring comparison with all relevant approved boundaries.

An aircraft-specific representation of relevant height and airspeed conditions affecting power-loss landing capability under its actual assumptions and limitations.

The temperature to which air must be cooled under the specified conditions to reach saturation, distinguished from a direct prediction of existing fog.

The observed or supplied temperature change with height in the atmosphere, compared with a lifted parcel's cooling rate when assessing stability.

A stability condition where an unsaturated lifted parcel and a saturated lifted parcel have different buoyancy responses under the given lapse rates.

Fog associated with moist air moving over a colder surface, distinguished from a requirement for exclusively night-time surface cooling.

Aircraft speed relative to the ground along the stated motion, distinguished from speed through the air or an uncorrected indicated airspeed.

Navigation using visible features and charted references to establish position, requiring reliable identification and continued awareness of terrain and obstacles.

Fuel available for the specified use under the aircraft definition, distinguished from total tank contents or a quantity that includes unusable fuel.

Favoring evidence that supports an existing belief while discounting conflicting evidence, rather than neutrally testing the belief against available observations.

A tendency to persist with an original plan despite cues that reconsideration or a change is needed, especially under commitment or completion pressure.

Concentrating on one indication or problem while neglecting other essential information, reducing awareness despite apparently intense attention to a task.

The person with the defined responsibility and final operational authority, whose duties remain distinct from equipment capability and air traffic clearance.

The applicable minimum condition under a specific rule, not an assurance that no additional margin is needed for actual circumstances.