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Lever class of retractable landing gear

Aviation Mechanic General (AMG) practice question 4 of 20 on Physics for Aviation. ACS element AM.I.J.K2 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic General (AMG) practice mode.

Question bank updated 2026-09-22

QUESTIONThe retractable main landing gear on an airplane pivots where it attaches to the airframe, has the wheel and brake assembly at the bottom, and is retracted by a hydraulic actuator attached between those points. This is an example of which class of lever?

  1. AThird class
  2. BFirst class
  3. CSecond class
Show the answer and explanation

Correct answer: A. Third class

  • A — correct In a third class lever the effort is applied between the fulcrum and the resistance. The gear attach point is the fulcrum, the wheel and brake assembly is the resistance, and the actuator in the middle is the effort.
  • B — incorrect A first class lever has the fulcrum between the effort and the resistance, as on a seesaw. On the landing gear the fulcrum is at one end.
  • C — incorrect A second class lever places the resistance between the fulcrum and the effort, as on a wheelbarrow. On the landing gear the effort, not the resistance, is in the middle.

BACKGROUND

Levers are grouped into three classes by the position of the fulcrum, effort, and resistance. First class levers have the fulcrum between effort and resistance (seesaw, crowbar). Second class levers have the fulcrum at one end, the effort at the other, and the resistance between them (wheelbarrow); they can only gain force. Third class levers have the fulcrum at one end, the resistance at the other, and the effort applied between them; they are used to speed up the movement of the resistance at the cost of greater effort. The retractable main landing gear is the handbook's example of a third class lever.

STUDY TIP

Identify the item in the middle: fulcrum in the middle means first class, resistance in the middle means second class, effort in the middle means third class.

KEY POINTS

  • Third class lever: effort is applied between fulcrum and resistance
  • Retractable landing gear with the actuator in the middle is third class
  • Third class levers gain speed of movement, not force

SOURCES

  • FAA-H-8083-30B ch05 "Third Class Lever"
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SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-30B Aviation Maintenance Technician Handbook – General, 14 CFR part 43 and part 65. Regulations and handbooks are revised; confirm details against the current edition.