100+ Free SACAA CPL(H) Aircraft Technical & General Practice Questions

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Sample SACAA CPL(H) Aircraft Technical & General Practice Questions

Try these sample questions to test your SACAA CPL(H) Aircraft Technical & General exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Which type of main rotor hub assembly allows individual rotor blades to flap, lead-lag (drag), and feather independently via mechanical hinges?

A.Fully articulated rotor system

B.Semi-rigid teetering rotor system

C.Rigid hingeless rotor system

D.Bearingless rotor system

Explanation: A fully articulated rotor system uses three distinct mechanical hinges per blade: a flapping hinge for vertical movement, a lead-lag (drag) hinge for horizontal movement in the plane of rotation, and a feathering hinge for pitch angle change. This design accommodates asymmetric lift and Coriolis forces independently for each blade.

2In a fully articulated main rotor head, what mechanical component is installed on the lead-lag hinge to prevent destructive blade hunting and ground resonance?

A.Hydraulically damped drag damper

B.Centrifugal droop stop

C.Collective friction lock

D.Pitch change swashplate scissor

Explanation: Hydraulic or elastomeric drag dampers are installed across the lead-lag (drag) hinges of articulated rotors to dampen blade acceleration and deceleration (hunting) caused by Coriolis force variations, stabilizing blade spacing and preventing ground resonance.

3Why are semi-rigid teetering rotor hubs mounted in an 'underslung' geometry relative to the teetering hinge pin?

A.To minimize shifts in the blade center of gravity relative to the mast center of rotation during flapping, reducing Coriolis accelerations

B.To increase maximum pitch range available during high-speed autorotation

C.To eliminate the requirement for collective control mixing units

D.To allow individual rotor blades to lead and lag independently without dampers

Explanation: Underslung mounting places the rotor blades' center of gravity below the teetering hinge axis. As the rotor disc flaps, the center of mass of the upward-flapping blade moves inward while the downward-flapping blade moves outward by an equal distance, neutralizing shifts in radial center of mass and minimizing Coriolis hunting stress.

4A helicopter equipped with a semi-rigid teetering rotor system experiences a low-G pushover maneuver. What critical structural phenomenon is likely to occur if cyclic control is applied abruptly?

A.Mast bumping due to severe flapping angle exceeding teetering hinge stops

B.Ground resonance caused by blade out-of-phase displacement

C.Thermal runaway of the main gearbox planetary gear stage

D.Sprag clutch slippage inside the freewheeling unit

Explanation: During a low-G or zero-G maneuver, total rotor thrust drops to near zero, removing fuselage trim authority. Severe cyclic inputs cause excessive rotor disc flapping relative to the mast, causing the rotor hub static stops to violently strike the main rotor mast (mast bumping), which can shear the mast.

5How do modern rigid (hingeless) rotor systems accommodate blade flapping and lead-lag stresses without mechanical hinge pins?

A.Through flexible composite structural elements at the blade root that flex under aerodynamic loads

B.By relying on automatic hydraulic pressure redistribution within the swashplate actuators

C.By utilizing variable geometry mast extensions that tilt according to air density

D.By mounting the entire main gearbox on flexible rubber isolators that swivel in flight

Explanation: Rigid (hingeless) rotor systems replace traditional mechanical pin-hinges with flexible composite blade root sections and elastomeric flexures that bend elastically under flapping and lead-lag forces while providing high control responsiveness.

6Which specific component connects the rotating swashplate ring to the main rotor mast to ensure it rotates synchronously at rotor RPM?

A.Rotating scissor links (torque links)

B.Stationary swashplate guide collar

C.Collective pitch mixing lever

D.Anti-torque control spider

Explanation: Rotating scissor links (also called rotating torque links) connect the rotating ring of the swashplate to the rotor mast or hub, driving the rotating ring at identical shaft speed while allowing it to tilt and slide vertically.

7Because of phase lag in a helicopter main rotor system, if maximum upward blade flapping response is required over the nose (12 o'clock position), where must the swashplate apply the maximum feathering pitch increase?

A.At the 3 o'clock position (90° prior in the direction of rotation)

B.At the 12 o'clock position directly over the nose

C.At the 6 o'clock position over the tail

D.At the 9 o'clock position (270° prior in the direction of rotation)

Explanation: Due to gyroscopic precession and aerodynamic phase lag, maximum mechanical pitch input applied to a blade produces its maximum displacement approximately 90 degrees later in the plane of rotation. To achieve maximum upward tilt over the nose (12 o'clock), maximum pitch must be applied at 3 o'clock (for counter-clockwise rotation).

8What is the primary difference between mechanical phase lag and advance angle in swashplate control linkages?

A.Phase lag is the aerodynamic response delay (~90°), while advance angle is the mechanical offset angle built into the swashplate pitch horn attachment to align cyclic inputs with pilot control axes

B.Phase lag only occurs in fixed-wing propellers, while advance angle is unique to tail rotors

C.Phase lag measures engine torque delay, while advance angle measures hydraulic servo pressure lag

D.Phase lag is present only in autorotation, while advance angle is present only in power-on hover

Explanation: Phase lag is the dynamic response property of a rotating rotor system where maximum blade flapping occurs roughly 90° after maximum pitch input. The advance angle is the physical design geometry (pitch link attachment location) engineered into swashplate linkages so that longitudinal cyclic movement yields pure nose-up or nose-down pitch without roll coupling.

9Main rotor coning angle is determined by the equilibrium between which two opposing physical forces?

A.Centrifugal force acting horizontally outward and total lift acting vertically upward

B.Engine torque acting rotationally and main gearbox friction acting downward

C.Tail rotor thrust acting laterally and fuselage parasite drag acting rearward

D.Profile drag acting along the chordline and induced drag acting parallel to the mast

Explanation: Rotor blade coning angle results from the vector sum of upward lift (which forces blades upward) and centrifugal force (which pulls blades horizontally outward). The resulting equilibrium angle between the rotor blade axis and the tip-path plane is the coning angle.

10What combination of flight conditions causes an excessive increase in main rotor blade coning angle, potentially exceeding structural bending limits?

A.High gross weight, low rotor RPM (NR), and high G-load maneuvers

B.Low gross weight, high rotor RPM (NR), and smooth level cruise flight

C.Low density altitude, zero payload, and rapid descent at flight idle

D.Full fuel capacity, flat pitch ground idle, and rotor brake engaged

Explanation: Coning angle increases when lift demands are high (high gross weight, steep turns, abrupt G-loads) and centrifugal forces are reduced (low rotor speed NR). This combination forces blades to cone upward steeply, increasing bending stress at the blade root.

About the SACAA CPL(H) Aircraft Technical & General Exam

The SACAA CPL(H) Aircraft Technical & General Knowledge examination is a mandatory theoretical knowledge subject for obtaining the Commercial Pilot Licence (Helicopter) under South African Civil Aviation Regulations (CAR Part 61). It assesses comprehensive operational knowledge of helicopter airframes, fully articulated, semi-rigid, and rigid main rotor systems, swashplate mechanics, anti-torque systems (conventional tail rotor, shrouded fenestron, and NOTAR), main gearbox and transmission assemblies, freewheeling unit sprag clutches, turboshaft engines (free power turbine, FADEC, governor functions), hydraulic flight control boosters, electrical power distribution, fuel systems, flight instrumentation, and rotor dynamic phenomena such as ground resonance, dynamic rollover, vortex ring state, and loss of tail rotor effectiveness (LTE).

Questions

40 scored questions

Time Limit

120 minutes

Passing Score

75%

Exam Fee

R450 per subject sitting under SACAA Part 187 user fees (South African Civil Aviation Authority (SACAA))

SACAA CPL(H) Aircraft Technical & General Exam Content Outline

20%

Main and Tail Rotor Systems

Fully articulated, semi-rigid teetering, rigid/hingeless rotor hub mechanics, swashplate linkages, lead-lag/flapping hinges, elastomeric bearings, and anti-torque configurations (conventional, fenestron, NOTAR).

15%

Transmission and Drive Assemblies

Main gearbox (MGB), intermediate and tail gearboxes, freewheeling unit sprag clutches, drive shafts, chip detectors, oil cooling, rotor brake systems, and centrifugal clutch mechanisms.

20%

Turboshaft and Piston Powerplants

Compressor, combustion, compressor turbine, free power turbine, hydromechanical/FADEC governors, engine instrumentation (TOT, ITT, N1, N2, torque), piston cooling fans, and engine anti-icing.

15%

Flight Controls and Hydraulics

Swashplate actuation, mechanical mixing units, hydraulic flight control boosters, accumulators, artificial feel systems, trim actuators, SAS, CSAS, and hydraulic failure manual reversion.

15%

Electrical, Fuel, and Instrument Systems

DC starter-generators, AC inverters, NiCad/lead-acid batteries, crashworthy fuel bladders, boost pumps, triple tachometers, torque meters, magnetic chip detectors, and pitot-static hover errors.

15%

Helicopter Operational Hazards and Dynamic Phenomena

Ground resonance mechanical instability, dynamic rollover pivot dynamics, vortex ring state aerodynamics/recovery, retreating blade stall limits, and loss of tail rotor effectiveness (LTE).

How to Pass the SACAA CPL(H) Aircraft Technical & General Exam

What You Need to Know

Passing score: 75%
Exam length: 40 questions
Time limit: 120 minutes
Exam fee: R450 per subject sitting under SACAA Part 187 user fees

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

SACAA CPL(H) Aircraft Technical & General Study Tips from Top Performers

1Thoroughly understand phase lag and advance angle (typically 90°): know how pitch inputs applied by the swashplate produce maximum aerodynamic blade response 90 degrees later in the plane of rotation.

2Understand the mechanics of freewheeling units (sprag clutch): explain how the free turbine disconnects from the main gearbox automatically when engine RPM drops below rotor RPM during autorotation.

3Differentiate between SAS (Stability Augmentation System) and Autopilot: SAS uses series actuators with limited authority (5-10%) without moving pilot flight controls, whereas autopilot uses parallel actuators with full control authority.

4Study ground resonance mechanics: identify lead-lag damper defects and out-of-phase blade spacing on articulated rotors, and know the immediate recovery action (lift off to hover if NR is normal, or immediate collective down and engine shutdown on the ground).

5Master turboshaft engine monitoring parameters: memorize relationships between N1 (gas generator RPM), N2/Nf (free power turbine RPM), NR (rotor RPM), TOT/ITT (turbine temperature limits), and torque percentage.

Frequently Asked Questions

What is the pass mark and time limit for the SACAA CPL(H) Technical General exam?

The pass mark is 75% under SACAA Part 61 regulations. The official PEXO computer-based exam contains 40 multiple-choice questions with a time limit of 120 minutes.

What is the fee for taking a SACAA CPL theory examination?

The examination fee is R450 per subject sitting as specified in SACAA Part 187 user fees (approved exam centres may levy an additional facility fee).

What core subjects are emphasized in the CPL(H) Technical General exam?

The exam heavily tests rotor head aerodynamics and mechanics (fully articulated vs semi-rigid vs rigid), turboshaft engine operation (free turbine, N1/N2 governors, TOT limits), transmission freewheeling units, hydraulic boosters, fenestron/NOTAR systems, and dynamic hazards like ground resonance, dynamic rollover, and LTE.

What are the validity rules for CPL(H) theory examination passes in South Africa?

Under SACAA CAR 61.01.10, candidates must pass all required CPL theoretical examinations within an 18-month window from the first subject pass. Once completed, the theoretical credits remain valid for 36 months toward licence issuance.

What is the difference between a fixed-wing and helicopter Technical General exam?

The CPL(H) exam specifically focuses on helicopter-unique mechanical systems (swashplates, drag dampeners, tail rotor drives, freewheeling units, turboshaft governors) and aerodynamic stability issues specific to rotary-wing flight (autorotation, vortex ring state, ground resonance, phase lag).

100+ Free SACAA CPL(H) Aircraft Technical & General Practice Questions

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