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Helicopter Systems

Understanding what makes up the helicopter you fly is the first step in becoming a safe, knowledgeable pilot. The FAA oral exam will test you on all of these systems. Each sub-page below is a focused reference covering one major aircraft system, with cross-links to related aerodynamics and emergency-procedure topics.

Study tools for this topic:

Mechanical systems

Rotor System

Fully articulated, semi-rigid (teetering), and rigid systems. The mechanical and operational differences.

Powerplant

Piston (Lycoming) vs turbine (Rolls 250, Arriel). Carb ice, mixture, hot starts, TGT limits.

Transmission & Drive

Main gearbox, freewheeling unit (sprag clutch), tail rotor drive shaft. The clutch that makes autorotation possible.

Tail Rotor

Anti-torque + yaw control. NOTAR, fenestron, tandem-rotor alternatives. 5-15% of engine power.

Aircraft systems

Fuel System

Avgas vs Jet-A, sumping for water, gauge accuracy, FAR fuel reserves (20 min day, 30 min night).

Electrical System

Alternator, battery, what's on the bus and what isn't. The engine keeps running with a complete electrical failure.

Flight Instruments

ASI, altimeter, VSI, tachometer, manifold pressure / torque, engine temperatures and oil pressure.

Pilot knowledge

Weight & Balance

Datum, arm, moment, CG envelope. Forward CG vs aft CG implications. Underloading and ballast.

Vibration Diagnostics

Frequency tells you the source — low (rotor), medium (tail rotor), high (engine/drive). Where you feel it matters too.

Cabri G2 Reference

Quick-reference performance numbers for the Guimbal Cabri G2. V-speeds, rotor RPM, fuel/oil specs.

Quick check on what you just learned: