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Blade movement in a fully articulated rotor

Aviation Mechanic Airframe (AMA) practice question 10 of 11 on Rotorcraft Fundamentals. ACS element AM.II.N.K4 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONIn a fully articulated rotor system, how is each individual blade able to move?

  1. AOnly in pitch, since no hinges permit flapping
  2. BAs a unit with the opposite blade in flap
  3. CIndependently in pitch, lead-lag, and flap
Show the answer and explanation

Correct answer: C. Independently in pitch, lead-lag, and flap

  • A — incorrect That describes the rigid rotor, in which the blade roots are rigidly attached to the hub and elastomeric bearings absorb the motions instead of hinges.
  • B — incorrect Blades connected so that one flaps up as the other flaps down is the semirigid design used on two-bladed rotors, not a fully articulated system.
  • C — correct A fully articulated rotor allows movement of each individual blade in three directions: rotation about the pitch axis, lead and lag in plane, and flapping up and down through a hinge independent of the other blades.

BACKGROUND

Main rotor systems are classified by how the blades attach and move relative to the hub, and there are three basic designs. A fully articulated rotor is found on aircraft with more than two blades and allows each blade to rotate about the pitch axis to change lift, to move back and forth in plane in lead and lag, and to flap up and down through a hinge independent of the other blades. The semirigid design is found on aircraft with two rotor blades, connected so that as one blade flaps up the opposite blade flaps down. The rigid rotor is a rare design in which the blade roots are rigidly attached to the hub with no hinges for lead-lag or flapping; the blades accommodate these motions through elastomeric bearings, molded rubber-like materials bonded to the parts that twist and flex instead of rotating.

STUDY TIP

Sort the three rotor types by blade count and hinges: more than two blades with three independent motions is fully articulated, two blades flapping as a pair is semirigid, and no hinges at all is rigid.

KEY POINTS

  • A fully articulated rotor is used on rotors with more than two blades.
  • Each blade can change pitch, lead and lag in plane, and flap independently of the others.
  • Semirigid rotors have two blades that flap as a pair; rigid rotors use elastomeric bearings in place of hinges.

SOURCES

  • FAA-H-8083-31B ch02 "Types of Rotor Systems — Fully Articulated Rotor" (sources/ama-airframe/ch02.txt)
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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.