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Helicopter force trim system control held

Aviation Mechanic Airframe (AMA) practice question 4 of 26 on Communications, Light Signals, and Runway Lighting Systems. ACS element AM.II.I.K18 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONThe simplest helicopter stability augmentation system (SAS) is a force trim system that uses a magnetic clutch and springs. Which control does it hold in the position at which it was released?

  1. AThe cyclic control
  2. BThe collective control
  3. CThe tail rotor pedals
Show the answer and explanation

Correct answer: A. The cyclic control

  • A — correct A force trim system uses a magnetic clutch and springs to hold the cyclic control in the position at which it was released.
  • B — incorrect The force trim system described for SAS acts on the cyclic, not on the collective.
  • C — incorrect The simplest SAS holds the cyclic; more advanced systems use electric actuators that make inputs to the hydraulic servos.

BACKGROUND

Some helicopters incorporate stability augmentation systems to help stabilize the helicopter in flight and in a hover. The simplest of these is a force trim system, which uses a magnetic clutch and springs to hold the cyclic control in the position at which it was released. More advanced systems use electric actuators that make inputs to the hydraulic servos, and those servos receive control commands from a computer that senses helicopter attitude. When other inputs such as heading, speed, altitude and navigation information are supplied to that computer, the result is a complete autopilot system. The SAS may be overridden or disconnected by the pilot at any time, and it reduces pilot workload by improving control harmony and decreasing disturbances.

STUDY TIP

Tie the three clues together: magnetic clutch, springs, and cyclic. Also remember the pilot can override or disconnect SAS at any time.

KEY POINTS

  • The simplest SAS is a force trim system using a magnetic clutch and springs.
  • It holds the cyclic control where the pilot released it.
  • More advanced systems drive hydraulic servos from an attitude-sensing computer and can be overridden at any time.

SOURCES

  • ama-airframe/ch02.txt "Stability Augmentation Systems (SAS)"
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SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-31B Aviation Maintenance Technician Handbook – Airframe, and 14 CFR part 43. Regulations and handbooks are revised; confirm details against the current edition.