Flight Controls

Objective

Upon completion of this lesson, the CFI candidate will demonstrate the ability to teach helicopter flight controls to include cyclic, collective, antitorque pedals, and throttle/governor systems. The candidate will explain the function, operation, and coordination of each control while demonstrating proper use and identifying associated risk factors. This lesson addresses ACS task HI.III.C and enables the CFI candidate to effectively instruct students on fundamental helicopter control systems.

Content

Introduction to Helicopter Flight Controls

Helicopter flight controls differ fundamentally from fixed-wing aircraft because helicopters must control both lift and thrust vectors continuously. Unlike an airplane where the wing provides lift and the propeller provides thrust in generally fixed directions, helicopter rotors must be adjusted constantly to control both magnitude and direction of the total rotor force.

The four primary flight controls work in coordination:

• Cyclic: Controls the tilt of the rotor disc (pitch and roll attitudes)
• Collective: Controls the pitch angle of all main rotor blades simultaneously (vertical flight)
• Antitorque pedals: Controls tail rotor thrust (yaw control and torque compensation)
• Throttle/Governor: Controls engine power and rotor RPM

Cyclic Control (HI.III.C.K1)

The cyclic control stick tilts the rotor disc by changing the pitch of individual rotor blades cyclically as they rotate around the disc. Forward cyclic input increases blade pitch on the retreating blade side (typically the back of the disc) and decreases it on the advancing blade side (typically the front), causing the rotor disc to tilt forward.

Key Teaching Points:

• Cyclic inputs are transmitted through the swash plate assembly
• Control response follows the 90-degree rule due to gyroscopic precession
• Small inputs produce significant aircraft responses
• Cyclic controls both pitch attitude and lateral movement

Common Student Errors:

• Over-controlling with large, rapid inputs
• Failing to understand the 90-degree phase lag
• Not coordinating cyclic with other controls

Collective Control (HI.III.C.K2)

The collective control raises or lowers the pitch angle of all main rotor blades simultaneously and equally. Raising the collective increases the angle of attack of all blades, increasing lift and requiring more engine power. The collective is the primary control for vertical flight.

Key Teaching Points:

• Collective changes affect both lift and power requirements
• Correlation exists between collective and throttle in non-governed helicopters
• Collective inputs affect rotor RPM if power is not adjusted accordingly
• Used primarily for altitude control in vertical flight and power management

Power-Pitch Relationship: When collective is raised without adding power, rotor RPM will decrease as the engine cannot maintain constant RPM against increased load. When collective is lowered without reducing power, rotor RPM will increase. This relationship is critical for maintaining rotor RPM within limits.

Antitorque Pedals (HI.III.C.K3)

The antitorque pedals control tail rotor blade pitch, which varies tail rotor thrust to counteract main rotor torque and provide yaw control. Left pedal input (in most helicopters) increases tail rotor pitch, pushing the tail right and yawing the nose left.

Key Teaching Points:

• Primary function is torque compensation, secondary is directional control
• Pedal inputs required change with power changes
• More left pedal needed with increased power (higher torque)
• Tail rotor effectiveness varies with forward airspeed
• Center of gravity affects pedal trim requirements

Torque-Pedal Relationship: As collective is raised and power increases, main rotor torque increases, requiring more left pedal to maintain heading. This relationship must be taught as a fundamental coordination requirement.

Throttle and Governor (HI.III.C.K4)

The throttle controls engine power output. In helicopters equipped with governors, the governor automatically adjusts throttle to maintain selected rotor RPM. In non-governed helicopters, the pilot must manually coordinate throttle with collective inputs to maintain rotor RPM.

Key Teaching Points:

• Governor-equipped helicopters: Set RPM and governor maintains it automatically
• Non-governed helicopters: Pilot must manually correlate power with collective
• Throttle response is not instantaneous - anticipation required
• Emergency procedures differ between governed and non-governed systems

Risk Management Elements

Use of Flight Controls (HI.III.C.R1)

Improper flight control use creates multiple hazards:

• Over-controlling: Leads to pilot-induced oscillations and loss of control
• Under-controlling: Results in inadequate aircraft response and potential unsafe conditions
• Abrupt inputs: Can exceed aircraft limitations or create passenger discomfort
• Lack of coordination: Creates uncoordinated flight with increased drag and reduced efficiency

Risk Mitigation:

• Emphasize smooth, deliberate control inputs
• Teach proper control pressure and displacement relationships
• Practice coordination exercises regularly
• Understand aircraft-specific control characteristics

Uncoordinated Flight (HI.III.C.R2)

Uncoordinated flight occurs when controls are not properly coordinated, typically manifested as slipping or skidding flight. In helicopters, this often results from improper pedal coordination with power changes or cyclic inputs.

Indicators of Uncoordinated Flight:

• Ball in slip/skid indicator displaced from center
• Vibrations or uncomfortable flight sensations
• Inefficient flight with increased drag
• Difficulty maintaining precise flight paths

Risk Mitigation:

• Teach the ball-centered principle
• Emphasize pedal coordination with all power changes
• Practice coordination exercises at various power settings
• Develop sensitivity to aircraft coordination cues

Flight Control Inputs Near Ground/Obstructions (HI.III.C.R3)

Flight control inputs near the ground or obstacles require special consideration due to:

• Reduced margin for error: Less time and space to recover from control errors
• Ground effect influences: Altered control effectiveness in ground effect
• Height/velocity limitations: Risk of entering unsafe height/velocity combinations
• Obstacle clearance: Risk of tail rotor or main rotor contact

Risk Mitigation:

• Plan all low-altitude maneuvers carefully
• Maintain awareness of height/velocity diagram limitations
• Consider wind effects on control requirements
• Ensure adequate clearance for all rotor systems
• Practice emergency procedures at altitude first

Control Coordination Principles

All helicopter controls must work together harmoniously:

1. Power-Attitude-Trim: Changes in one require adjustments in others
2. Anticipation: Control inputs should anticipate aircraft response lag
3. Progressive Application: Smooth, progressive inputs prevent over-controlling
4. Coordination Scanning: Continuous monitoring of all flight instruments

Schedule

Equipment

Required References

• FAA-H-8083-21A Helicopter Flying Handbook
• FAA-H-8083-4 Helicopter Instructor’s Handbook
• FAA-S-ACS-29 Helicopter CFI Airman Certification Standards
• Helicopter Flight Manual/POH for specific aircraft

Visual Aids and Materials

• Helicopter control system diagrams
• Swash plate cutaway model or diagram
• Ball slip/skid indicator demonstration model
• Height/velocity diagram chart
• Whiteboard/markers for drawing control relationships
• Video examples of coordinated vs uncoordinated flight (if available)

Aircraft/Training Device

• Representative helicopter or approved flight training device
• Functional flight controls for demonstration
• Operating flight instruments including slip/skid indicator

Instructor Actions

The CFI candidate will:

1. Demonstrate cyclic operation by showing stick movements and explaining corresponding rotor disc tilt and aircraft response, emphasizing the 90-degree rule and gyroscopic precession effects

2. Operate collective control while explaining power-pitch relationships, demonstrating how collective changes affect rotor RPM and power requirements

3. Demonstrate antitorque pedals by showing pedal inputs and explaining torque compensation requirements, relating pedal position to power settings

4. Explain throttle/governor systems by demonstrating throttle operation and governor function (if equipped), showing differences between governed and manual throttle control

5. Show control coordination by demonstrating smooth, coordinated control inputs during representative flight maneuvers, emphasizing the relationship between all controls

6. Identify risk factors by explaining scenarios involving over-controlling, uncoordinated flight, and hazardous control inputs near obstacles

7. Demonstrate teaching techniques including clear explanations, logical sequence, and appropriate use of analogy to help students understand control functions

8. Assess student understanding through questioning techniques and guided practice scenarios

Student Actions

The evaluating DPE will observe that the CFI candidate can:

1. Explain control functions clearly using appropriate terminology and logical sequence

2. Demonstrate proper control technique showing smooth, coordinated inputs

3. Identify control system components and their relationship to aircraft control

4. Recognize coordination errors and explain correction techniques

5. Apply risk management principles to control use scenarios

6. Answer questions about control systems, limitations, and emergency procedures

7. Adapt teaching methods to different learning styles and experience levels

8. Provide appropriate feedback on control technique and coordination

Completion Standards

The CFI candidate demonstrates instructional competency in helicopter flight controls when they can:

Knowledge Standards (HI.III.C):

• Accurately explain cyclic control function, swash plate operation, and gyroscopic effects (HI.III.C.K1)
• Clearly describe collective control operation and power-pitch relationships (HI.III.C.K2)
• Demonstrate understanding of antitorque pedal function and torque compensation (HI.III.C.K3)
• Explain throttle and governor operation for both equipped and non-equipped helicopters (HI.III.C.K4)

Risk Management Standards (HI.III.C):

• Identify and explain risks associated with improper control use (HI.III.C.R1)
• Recognize and demonstrate correction of uncoordinated flight (HI.III.C.R2)
• Assess risks of control inputs near ground or obstacles and explain mitigation strategies (HI.III.C.R3)

Skill Standards (HI.III.C):

• Demonstrate smooth, coordinated operation of all flight controls (HI.III.C.S1)
• Show proper control technique while providing clear, concurrent explanation
• Maintain aircraft within normal operating parameters during demonstrations
• Execute control movements that are appropriate for instructional demonstration

Teaching Standards:

• Present information in logical, understandable sequence
• Use effective questioning and feedback techniques
• Demonstrate ability to identify and correct common student errors
• Show competency in explaining complex control relationships
• Maintain professional instructional demeanor throughout lesson