100+ Free SAR-66 Module 12 Practice Questions

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2026 Statistics

Key Facts: SAR-66 Module 12 Exam

128 Q / 160 min

Module 12 Official Exam Format

CAAS AC 66-13 (Rev 1)

75%

Passing Mark

SAR-66 Appendix 2

S$87.20

Exam Fee (from 1 Jan 2026)

ANO Twelfth Schedule para 11

B1.3 / B1.4

Licence Subcategories

SAR-66

CAAS SAR-66 Module 12 tests helicopter aerodynamics, structures, rotor systems, transmissions, and utility systems for Singapore B1.3 and B1.4 licence candidates. The official CAAS paper has 128 MCQs in 160 minutes (Part 1 56 Q / 70 min + Part 2 72 Q / 90 min) with a 75% passing mark. Key topics include autorotation dynamics, dissymmetry of lift, cyclic/collective pitch controls, swashplate mechanics, blade tracking, main/tail gearboxes, freewheeling units, rotor hub configurations, and airframe structural maintenance. Examination fee is S$87.20 under the ANO Twelfth Schedule from 1 January 2026.

Sample SAR-66 Module 12 Practice Questions

Try these sample questions to test your SAR-66 Module 12 exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1What aerodynamic phenomenon causes a helicopter to tilt to the left or right during forward flight unless compensated for by cyclic pitch control?

A.Dissymmetry of lift

B.Vortex ring state

C.Transverse flow effect

D.Ground effect

Explanation: Dissymmetry of lift occurs in forward flight because the advancing blade experiences a higher relative airflow velocity (rotational speed plus forward speed) than the retreating blade (rotational speed minus forward speed). Without blade flapping or cyclic control, the advancing blade generates more lift, causing a rolling moment.

2Due to gyroscopic precession, if a force is applied perpendicular to the plane of rotation of a main rotor blade, where does the maximum aerodynamic response (displacement) occur?

A.At the point of force application

B.90 degrees later in the direction of rotation

C.180 degrees opposite the point of force application

D.45 degrees before the point of force application

Explanation: Gyroscopic precession causes a rigid or articulated rotor disc to react to an applied force 90 degrees further in the direction of rotation. Therefore, to pitch the rotor disc forward, cyclic pitch control must alter blade pitch 90 degrees earlier in the rotational cycle.

3In a fully articulated main rotor head, what mechanical component allows the individual rotor blades to move forward and backward in the plane of rotation to absorb acceleration and deceleration forces?

A.Flapping hinge

B.Lead-lag (drag) hinge

C.Pitch change feathering hinge

D.Teetering pin

Explanation: The lead-lag hinge (also called drag hinge) allows the blade to lead or lag in the plane of rotation. This motion absorbs the severe Coriolis forces created when the blade flaps up and down and changes its effective radius of gyration.

4What is the primary function of the freewheeling unit (sprag clutch) located between the helicopter engine and the main gearbox?

A.To disengage the tail rotor during engine starting

B.To automatically disengage the engine from the transmission in the event of engine failure, permitting autorotation

C.To vary transmission gear ratio according to flight speed

D.To lock the main rotor blades during ground parking

Explanation: The freewheeling unit automatically disengages the dead engine from the main transmission whenever transmission RPM exceeds engine output shaft RPM. This prevents engine drag from stopping the rotor, allowing the rotor blades to continue spinning freely driven by airflow during autorotation.

5During autorotation following a engine failure, which region of the main rotor blade along its span acts as the driving region (generating forward aerodynamic force to keep the rotor turning)?

A.The root region (inner 25%)

B.The mid-blade region (approximately 25% to 70% span)

C.The blade tip region (outer 30%)

D.The entire blade span uniformly

Explanation: In autorotation, up-flowing air creates a total aerodynamic force vector tilted forward of the axis of rotation in the mid-blade region (approx 25% to 70% span). This region supplies the driving force that accelerates the rotor and overcomes the dragging force of the blade tips and root.

6How does raising the collective pitch lever affect the main rotor blades and engine fuel control unit in a turbine helicopter?

A.It increases the pitch angle of all main rotor blades simultaneously and signals the governor/FCU to increase fuel flow to maintain rotor RPM

B.It changes blade pitch differentially around the rotor azimuth without altering fuel flow

C.It decreases rotor blade pitch while increasing engine RPM

D.It tilts the swashplate assembly laterally without altering collective pitch

Explanation: The collective control increases the pitch angle of all main rotor blades equally and simultaneously. To prevent rotor RPM from drooping due to increased blade drag, a mechanical linkage or electronic governor signals the engine fuel control unit (FCU) to increase fuel flow.

7A low-frequency lateral vibration occurring at a frequency of 1 per revolution (1:1 rotor speed) in a helicopter is most commonly caused by which discrepancy?

A.Main rotor blade out-of-track (blade flying higher or lower)

B.Main rotor blade mass out-of-balance (weight discrepancy)

C.Tail rotor drive shaft unbalance

D.Engine turbine wheel unbalance

Explanation: A 1-per-revolution lateral vibration is caused by mass unbalance of the main rotor assembly (a spanwise or chordwise weight imbalance). In contrast, a 1-per-revolution vertical vibration is typically caused by aerodynamic unbalance (blade out of track).

8What is the function of the swashplate assembly in a helicopter flight control system?

A.To convert non-rotating flight control inputs from cyclic and collective linkages into rotating control inputs delivered to the pitch horns

B.To automatically balance tail rotor thrust against main rotor torque

C.To disconnect the flight controls during autopilot engagement

D.To damper blade lead-lag motion in high-speed flight

Explanation: The swashplate consists of an inner stationary ring connected to the airframe flight control rods and an outer rotating ring that turns with the main rotor mast. It converts non-rotating control movements into rotating pitch change signals transmitted via pitch links to the blade pitch horns.

9In a semi-rigid two-bladed teetering rotor system, what dangerous dynamic condition can occur if the helicopter experiences a low-G flight maneuver?

A.Ground resonance

B.Mast bumping

C.Vortex ring state

D.Thermal runaway

Explanation: In low-G (weightless or negative-G) conditions, main rotor thrust drops significantly, reducing rotor control authority. If the pilot attempts a rapid roll correction, the main rotor hub can flap beyond its allowable angular limit, causing the static stop of the rotor hub to strike the main rotor mast (mast bumping), leading to mast separation.

10What type of tail rotor replacement design utilizes a multi-bladed shrouded fan built directly into the vertical tail fin structure?

A.NOTAR (NO TAil Rotor)

B.Fenestron (ducted fan)

C.Tandem rotor

D.Coaxial rotor

Explanation: The Fenestron (or ducted fan) is an anti-torque system featuring a multi-bladed fan enclosed within a housing built into the vertical tail fin. It improves ground safety, reduces tail noise, and protects anti-torque blades from foreign object damage.

About the SAR-66 Module 12 Exam

CAAS SAR-66 Module 12 (Helicopter Aerodynamics, Structures and Systems) is the basic knowledge examination for Singapore Aircraft Maintenance Licence Category B1.3 (turbine helicopter) and B1.4 (piston helicopter) candidates. Per CAAS AC 66-13 (Rev 1), the official exam comprises 128 multiple-choice questions administered over 160 minutes in two parts (Part 1: 56 questions in 70 minutes; Part 2: 72 questions in 90 minutes) with a 75% pass mark. The syllabus covers rotary-wing aerodynamics, autorotation, flight controls, blade tracking, vibration analysis, main and tail rotor heads, gearboxes and transmissions, airframe structures, and helicopter utility systems.

Questions

128 scored questions

Time Limit

160 minutes

Passing Score

75%

Exam Fee

S$87.20 per basic knowledge examination paper (Air Navigation Order Twelfth Schedule from 1 Jan 2026) (Civil Aviation Authority of Singapore (CAAS))

SAR-66 Module 12 Exam Content Outline

15%

Theory of Flight & Rotary Wing Aerodynamics

Main rotor airflow, lift vector, autorotation, ground effect, translational drift, dissymmetry of lift, gyroscopic precession and autorotative flare

15%

Flight Control Systems & Rotor Dynamics

Cyclic and collective pitch control, swashplate assembly, mixing unit, yaw control, tail rotor, ducted fan (Fenestron), and stability augmentation systems

10%

Blade Tracking & Vibration Analysis

Dynamic balancing, blade tracking methods (flag, optical, strobe, health monitoring), low and high frequency vibration diagnosis and damper maintenance

15%

Transmissions & Drive Systems

Main gearbox, intermediate and tail gearboxes, freewheeling unit, clutch assemblies, rotor brake systems, drive shafts and chip detectors

15%

Main & Tail Rotor Systems

Fully articulated, semi-rigid, and rigid rotor heads, blade construction, lead-lag hinges, flapping hinges, pitch change mechanisms, and tail rotor hubs

30%

Airframe Structures & Utility Systems

Helicopter fuselage, tail boom, landing gear/floats, hydraulics, electrical power, fuel systems, air conditioning, fire protection, and avionic integration

How to Pass the SAR-66 Module 12 Exam

What You Need to Know

Passing score: 75%
Exam length: 128 questions
Time limit: 160 minutes
Exam fee: S$87.20 per basic knowledge examination paper (Air Navigation Order Twelfth Schedule from 1 Jan 2026)

Keys to Passing

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

SAR-66 Module 12 Study Tips from Top Performers

1Master rotary wing aerodynamic concepts such as dissymmetry of lift, gyroscopic precession, translational drift, and autorotation airflow vectors.

2Understand the mechanical operation of swashplate assemblies, collective/cyclic pitch mixing, lead-lag hinges, and lead-lag dampers.

3Study helicopter transmission components: freewheeling units, main gearboxes, tail rotor drive shafts, and magnetic chip detector operation.

4Review blade tracking and vibration troubleshooting techniques (identifying 1/rev vertical vs lateral vibrations vs high frequency tail rotor vibes).

Frequently Asked Questions

What is CAAS SAR-66 Module 12?

Module 12 is the CAAS basic knowledge examination paper covering Helicopter Aerodynamics, Structures and Systems required for Singapore SAR-66 Category B1.3 (turbine helicopter) and Category B1.4 (piston helicopter) Aircraft Maintenance Licences.

What is the official format and duration of the Module 12 exam?

Per CAAS AC 66-13 (Rev 1), the official Module 12 examination consists of 128 multiple-choice questions with a total time of 160 minutes, split into Part 1 (56 questions, 70 minutes) and Part 2 (72 questions, 90 minutes). The passing score is 75%.

What topics are covered in Module 12?

The syllabus includes rotary wing aerodynamics, autorotation, cyclic and collective pitch controls, swashplate mechanics, blade tracking, vibration analysis, main/tail gearboxes, freewheeling units, rotor head mechanisms, helicopter structures, and utility systems.

What is the exam fee for Module 12 in Singapore?

The examination fee is S$87.20 per basic knowledge examination paper under paragraph 11 of the Air Navigation Order Twelfth Schedule (effective 1 January 2026; previously S$80).