Rotorcraft Fundamentals Oral Exam Questions and Answers
These rotorcraft fundamentals oral exam questions and answers cover AM.II.N. For the O&P, explain how the rotor system produces and balances lift, responds to controls, and keeps turning during autorotation.
On this page
What should my answer explain?
Our study tip: Follow the installed rotor system’s design and manufacturer’s procedures. Use these explanations for oral practice; tracking, balancing, and ground operation require the aircraft-specific instructions.
FAA-S-ACS-1, printed 42, PDF 47 · AM.II.N: Rotorcraft Fundamentals
Which ACS elements do these questions practice?
The table maps each study prompt to its ACS element. It is not a prediction of assigned test questions.
| ACS element | Study focus |
|---|---|
| AM.II.N.K5 | Design, type, and operation of rotor systems. |
| AM.II.N.K1 | Rotorcraft aerodynamics. |
| AM.II.N.K2 | Flight controls. |
| AM.II.N.K3 | Transmissions. |
| AM.II.N.K8 | Rotor vibrations, track, and balance. |
| AM.II.N.R4 | Maintenance and inspection of rotorcraft systems and components. |
Which oral exam questions can I practice?
These practice questions are built from ACS elements; they are not actual FAA test questions.
1. What movements does a fully articulated rotor allow?
ACS: AM.II.N.K5
Each blade can change pitch, lead and lag in the rotor plane, and flap up and down independently through a hinge. This design is found on aircraft with more than two blades.
FAA-H-8083-31B, Airframe, printed 2-17, PDF 88
2. How do the blades flap in a two-blade semirigid rotor?
ACS: AM.II.N.K5
A teetering hinge lets the blades flap as a unit: when one blade flaps up, the other flaps down.
FAA-H-8083-31B, Airframe, printed 2-25, PDF 96
3. Why does forward flight create dissymmetry of lift, and how does flapping compensate?
ACS: AM.II.N.K1
Forward speed increases the relative wind on the advancing blade and reduces it on the retreating blade, so the advancing side of the disc produces more lift than the retreating side. The blades flap and feather automatically to equalize lift: upward flapping reduces the advancing blade’s angle of attack and lift, and downward flapping increases angle of attack and lift on the retreating side.
FAA-H-8083-31B, Airframe, printed 2-24, PDF 95 · FAA-H-8083-31B, Airframe, printed 2-25, PDF 96
4. What is translational lift, and why does rotor efficiency improve?
ACS: AM.II.N.K1
Improved rotor efficiency resulting from directional flight is called translational lift. As incoming wind from aircraft movement or surface wind enters the rotor system, turbulence and vortices are left behind and the airflow becomes more horizontal.
FAA-H-8083-31B, Airframe, printed 2-23, PDF 94
5. What happens to blade pitch when the collective is raised or lowered?
ACS: AM.II.N.K2
Raising the collective produces a simultaneous, equal increase in pitch angle on all main rotor blades. Lowering it produces a simultaneous, equal decrease.
FAA-H-8083-31B, Airframe, printed 2-27, PDF 98
6. What does moving the cyclic do to the rotor disc and helicopter motion?
ACS: AM.II.N.K2
The cyclic tilts the tip-path plane in the desired horizontal direction. The rotor disc tilts in the direction the cyclic moves, changing the direction of rotor force and controlling helicopter attitude and airspeed. Because the rotor disc acts like a gyro, the cyclic linkage is rigged to decrease blade pitch approximately 90° before the blade reaches the direction of cyclic displacement and increase it approximately 90° after it passes.
FAA-H-8083-31B, Airframe, printed 2-28, PDF 99
7. How does the swash plate carry collective and cyclic inputs to the blades?
ACS: AM.II.N.K2
The stationary swash plate is connected to the controls and is restrained from rotating, but can tilt and move vertically. The rotating plate turns with the mast; both plates tilt and slide together, and pitch links connect the rotating plate to the pitch horns.
FAA-H-8083-31B, Airframe, printed 2-27, PDF 98
8. Why is a freewheeling unit needed?
ACS: AM.II.N.K3
The rotor must remain free to turn if the engine fails. The unit automatically disconnects the engine when engine rpm falls below main rotor rpm, allowing the main and tail rotors to continue turning at normal in-flight speeds.
FAA-H-8083-31B, Airframe, printed 2-35, PDF 106
9. How does an electronic balancing kit such as the Vibrex help locate a rotor correction?
ACS: AM.II.N.K8
The Vibrex kit measures the vibration induced by the main and tail rotors and analyzes the vibration from out-of-track or out-of-balance rotors. Plotting vibration amplitude and clock angle on a chart then shows the amount and location of the track or weight change. The Vibrex is also used in troubleshooting, by measuring the vibration levels and frequencies or rpm of unknown disturbances.
FAA-H-8083-31B, Airframe, printed 2-32, PDF 103
10. What are the main rotor transmission’s purposes?
ACS: AM.II.N.K3
The main rotor transmission’s primary purpose is to reduce engine output rpm to optimum rotor rpm. With a horizontally mounted engine, it also changes the horizontal engine axis of rotation to the vertical rotor-shaft axis.
FAA-H-8083-31B, Airframe, printed 2-34, PDF 105
How do I rehearse the answer out loud?
Read the question, put the answer aside, and give a connected explanation. Then compare your answer with the cited FAA page and repeat the prompt. This is our study routine, not an FAA scoring rule.
For actual maintenance, use the applicable manufacturer’s instructions and aircraft-specific data. These short study answers are not complete maintenance procedures.
What else should I know?
Why does a change in engine power require attention to torque compensation?
Because fuselage torque effect changes with the engine power supplied to the main rotor. More engine power produces more torque effect.
ACS: AM.II.N.K1 · FAA-H-8083-31B, Airframe, printed 2-18, PDF 89
Does every helicopter need a separate tail rotor for antitorque?
No. Counterrotating rotors on a dual-rotor helicopter balance aerodynamic torque and eliminate the need for a separate antitorque system. NOTAR, another design, has no tail rotor and uses air directed through a series of slots in the tail boom.
ACS: AM.II.N.K5 · FAA-H-8083-31B, Airframe, printed 2-17, PDF 88 · FAA-H-8083-31B, Airframe, printed 2-18, PDF 89
What indications can accompany retreating blade stall?
A nose-up pitch, vibration, and a rolling tendency can occur. The roll is usually left for a helicopter with counterclockwise rotor rotation; the stall develops at high forward speed from high angle of attack and slow relative wind on the retreating blade.
ACS: AM.II.N.K1 · FAA-H-8083-31B, Airframe, printed 2-25, PDF 96
Why protect holes in a rotor blade during preservation and storage?
To keep moisture out of the blade interior and prevent corrosion. For preservation, tape the holes and clean the exterior with mild soap and water.
ACS: AM.II.N.R4 · FAA-H-8083-31B, Airframe, printed 2-33, PDF 104
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Start your free drillWhich guide should I read next?
- Flight Controls and Rigging Oral Exam Questions and Answers
- Airframe Inspection Oral Exam Questions and Answers
- Airframe Oral Exam Questions: What a DME Asks
Which sources support these answers?
Sources were checked on October 19, 2026. Handbook citations identify the printed and PDF pages.
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