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

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

Try these sample questions to test your SACAA ATPL(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.

1In a free-turbine turboshaft engine utilized in multi-engine helicopters, what is the fundamental mechanical relationship between the gas generator turbine (N1/Ng) and the power turbine (N2/Np)?

A.They \are mechanically decoupled and connected only aerodynamically by the gas flow

B.They \are rigidly mounted on a single common shaft rotating at identical RPM

C.They \are connected through a fixed 2:1 reduction gear train inside the accessory gearbox

D.They \are synchronized electronically via the FADEC through a torque-converter clutch

Explanation: A free-turbine turboshaft engine features a gas generator section (compressor, combustion chamber, high-pressure turbine) that is mechanically independent of the power turbine (N2/Np). The power turbine is driven strictly by the kinetic and thermal energy of the expanding exhaust gas stream produced by the gas generator.

2When the collective pitch is increased on a multi-engine turbine helicopter, how does a free-turbine engine governor maintain constant rotor RPM (NR / N2)?

A.It senses the impending drop in N2/NR speed and increases fuel flow to increase N1/Ng speed and gas energy

B.It increases power turbine shaft pitch to match the increased main rotor resistance directly

C.It opens variable inlet guide vanes (VIGVs) to bypass excess gas \around the power turbine stage

D.It mechanically advances the N2 turbine governor flyweights to increase power turbine gear ratio

Explanation: Increasing collective pitch increases main rotor drag, causing main rotor (NR) and power turbine (N2/Np) RPM to drop. The N2 governor senses this reduction and commands the fuel control system to inject more fuel into the combustion chamber, increasing N1/Ng gas generator speed and mass flow to restore N2/NR.

3What is the primary operational advantage of a dual-spool gas generator (N1 low-pressure spool and N2 high-pressure spool) in advanced turboshaft engines?

A.Higher compressor pressure ratios with improved stall margins and better acceleration response across operating altitudes

B.Direct mechanical drive of the tail rotor from the low-pressure spool without needing a combining gearbox

C.Elimination of the need for an oil lubrication system on the high-pressure spool bearings

D.Ability to run the compressor in reverse direction during autorotation to generate zero drag

Explanation: Dual-spool gas generators allow the low-pressure and high-pressure compressors to rotate at independently optimized speeds. This increases overall compressor pressure ratio and thermal efficiency while significantly reducing susceptibility to axial compressor surge and stall during rapid throttle transients.

4In a dual-channel Full Authority Digital Engine Control (FADEC) system on a multi-engine helicopter, how \are control commands executed during normal operation?

A.One channel is active controlling engine parameters while the second channel operates in standby, cross-checking computations

B.Both channels command separate fuel metering valves simultaneously, summing their outputs mechanically

C.Channel A controls engine N1 speed while Channel B independently controls N2 speed without data sharing

D.The active channel alternates every 60 seconds automatically during flight to balance electronic component wear

Explanation: Dual-channel FADEC \architecture utilizes an Active/Standby configuration (or active/lane \architecture) where one Electronic Control Unit (ECU) channel actively controls the engine stepper motor/stepper valve while cross-monitoring data from the standby channel. If a self-diagnostic fault is detected in the active channel, control seamlessly transfers to the standby channel.

5What happens if a dual-channel FADEC system suffers a total electrical failure or dual channel loss in flight on a turbine helicopter equipped with hydromechanical backup?

A.The system freezes the fuel metering valve at its last valid position or reverts to manual hydro-mechanical control

B.The engine immediately shuts down and cannot be restarted until ground maintenance clears the ECU fault memory

C.The engine accelerates uncontrollably to maximum overspeed until the mechanical N2 governor trips the shutoff valve

D.The standby FADEC channel drains hydraulic pressure to force the fuel control lever to flight idle

Explanation: Total dual-channel FADEC failure results in either a 'fail-fixed' mode (freezing fuel flow at the last valid state) or automatic reversion to a manual hydro-mechanical control mode (yellow warning light), requiring the pilot to manually manage throttle/twist grip inputs for that engine.

6Under SACAA certification standards, what is the maximum time limit for utilizing 30-Second One Engine Inoperative (OEI) power rating on a multi-engine turbine helicopter?

A.30 seconds maximum, intended only for absolute emergency completion of takeoff or balked landing following an engine failure

B.2 minutes, provided Turbine Outlet Temperature (TOT) remains below the redline threshold

C.5 minutes, usable during any single-engine hover out of ground effect (OGE)

D.30 minutes, provided the second engine fuel crossfeed is opened within 1 minute

Explanation: The 30-Second OEI rating is an emergency power rating certified for Category A multi-engine helicopters. It provides maximum contingency power for up to 30 seconds to allow safe continuation of takeoff or landing following an engine failure, after which power must be reduced to 2-Minute OEI or Continuous OEI.

7What maintenance action is mandatory following an operational event where the 30-Second OEI power rating limit was exceeded by more than 5 seconds?

A.Detailed inspection and possible overhaul or replacement of hot section turbine components as specified by the engine manual

B.Rinse the engine compressor with demineralized water and reset the FADEC operational fault counter

C.Drain and replace the main transmission synthetic oil and replace the magnetic chip detector plug

D.Re-calibrate the hydro-mechanical fuel control unit flyweight spring and perform a 10-minute ground run

Explanation: Because 30-Second OEI power subjects turbine blades and combustion liners to extreme temperatures near thermal deformation limits, exceeding this rating duration mandates engine recording system (HUMS/FADEC) log review followed by hot-section teardown, non-destructive inspection, or blade replacement.

8How does Continuous OEI power rating compare to Maximum Continuous Power (MCP) in twin-turbine helicopters?

A.Continuous OEI is higher than twin-engine MCP, allowing single-engine en-route flight without time limit

B.Continuous OEI is lower than twin-engine MCP to protect the remaining engine from thermal fatigue

C.Continuous OEI is identical in torque output to 30-Second OEI power but restricted to sea level operations

D.Continuous OEI can only be selected manually by pulling the emergency engine over-speed shutoff valve

Explanation: Continuous OEI power is higher than normal twin-engine Maximum Continuous Power (MCP) to enable the helicopter to sustain climb or cruise flight on one engine indefinitely without time restriction, within single-engine thermal and mechanical design limits.

9What triggers Automatic Power Upregulation (OEI Auto-stroke / Auto-power bump) on modern FADEC-equipped twin-engine helicopters?

A.Detection of an engine failure condition such as N1 drop, torque loss, or N2 divergence on one engine

B.Selecting the landing gear retract switch while collective pitch is above 50%

C.Exceeding 100 knots indicated airspeed in forward cruising flight

D.Pressing the cyclic magnetic trim release button for longer than 3 seconds

Explanation: FADEC monitors engine parameters (N1, N2, torque, fuel flow, oil pressure). When a sudden drop in torque or N1 is detected on one engine indicating engine failure, the FADEC automatically upregulates the operating engine's fuel schedule to OEI power limits without pilot action.

10What physical phenomenon causes an axial compressor stall in a turboshaft engine?

A.Breakdown of smooth airflow over the compressor rotor blades due to excessive angle of attack on the compressor airfoils

B.Ignition of unburned fuel in the power turbine exhaust duct causing reverse flow back to the intake

C.Over-speeding of the power turbine relative to the main transmission reduction gear ratio

D.Freezing of moisture in the diffuser casing creating a physical blockage of high-pressure air

Explanation: Compressor stall occurs when the angle of attack of airflow over compressor rotor blades exceeds the critical stall angle. This results in boundary layer separation, reduced airflow velocity, pressure reversal, and potentially complete compressor surge.

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

The SACAA ATPL(H) Aircraft Technical & General Knowledge examination tests candidate mastery of complex multi-engine turbine helicopter systems, powerplants, and mechanical dynamics. Topics include free-turbine turboshaft operating principles, FADEC architecture, One Engine Inoperative (OEI) power limits, main combining gearboxes, freewheeling sprag clutches, chip detectors, dual hydraulic flight controls, SAS and 4-axis AFCS, elastomeric rotor bearings, dynamic vibration absorbers, crashworthy fuel bladders, DC/AC electrical generation, and electro-thermal rotor ice protection.

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 ATPL(H) Aircraft Technical & General Exam Content Outline

22%

Turboshaft Engines & Powerplants

Free turbine vs fixed spool dynamics, FADEC architecture and fail-safe modes, OEI emergency power ratings (30-sec, 2-min, continuous OEI), bleed air systems, variable inlet guide vanes, engine monitoring (IVHM/NVG), and particle separators.

20%

Main & Tail Transmission Systems

Combining gearboxes (MGB), intermediate and tail gearboxes, sprag clutches / freewheeling units, dual oil pumps and coolers, magnetic chip detectors, pulsed electrical chip burners, hydraulic rotor brakes, and torquemeter principles.

16%

Hydraulic Flight Control Systems

Dual redundant hydraulic flight control boosters, irreversible cyclic/collective controls, gradient spring feel packages, hydraulic failure modes, manual reversion, hydraulic accumulators, and fluid properties.

14%

SAS, AFCS & Autopilot Systems

Stability Augmentation Systems (SAS) rate gyros and series limited-authority actuators, Automatic Flight Control Systems (AFCS) parallel full-authority trim actuators, 4-axis flight directors, auto-hover, SAR modes, and magnetic brake trim.

12%

Main & Tail Rotor Systems & Dynamics

Fully articulated, semi-rigid, and rigid rotor hubs, elastomeric radial and thrust bearings, lead-lag dampers, Coriolis compensation, bifilar/pendulum absorbers, active vibration control systems (AVCS), Fenestron, and NOTAR systems.

16%

Fuel Systems, Electrical & Ice Protection

Crashworthy self-sealing fuel bladders, crossfeed and suction defueling, DC starter-generators, GCUs, inverter systems, bus tie logic, electro-thermal rotor blade de-icing, engine bleed anti-icing, and optical ice sensors.

How to Pass the SACAA ATPL(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 ATPL(H) Aircraft Technical & General Study Tips from Top Performers

1Memorize turboshaft operational limits: understand how N1/Ng (gas generator RPM) relates to compressor pressure ratio while N2/Np (power turbine RPM) drives the main gearbox at constant NR.

2Understand 30-second and 2-minute OEI emergency ratings, including mandatory engine inspection/overhaul triggers when OEI ratings are exceeded.

3Distinguish between series (SAS) and parallel (AFCS/Autopilot) actuators: series actuators are limited authority (typically ±10%) and do not feedback to stick; parallel actuators move the flight controls throughout 100% range.

4Master main transmission drive components: sprag clutch freewheeling action during autorotation, phase-displacement hydromechanical torquemeters, and chip burner operation.

5Study rotor head dynamics: elastomeric bearing shear motion, Coriolis force lead-lag blade movement, bifilar pendulum dampers, and active vibration control actuators.

Frequently Asked Questions

What is the format and duration of the SACAA ATPL(H) Aircraft Technical & General exam?

The official exam is a 40-question computer-based test (PEXO) allowed 120 minutes, requiring a minimum score of 75% to pass under SACAA regulations.

What power ratings are emphasized in multi-engine turboshaft questions?

Questions cover Takeoff Power (TOP), Maximum Continuous Power (MCP), 30-Second OEI, 2-Minute OEI, and Continuous OEI power limits, including FADEC automatic power upregulation during engine failures.

How are flight control systems differentiated between SAS and AFCS in ATPL(H)?

SAS utilizes fast, limited-authority series actuators operating without moving cyclic controls to augment short-term rate stability. AFCS/Autopilot utilizes slow, full-authority parallel actuators that move the flight control stick to maintain long-term attitude, altitude, or airspeed.

What transmission warning systems are tested?

The exam heavily tests magnetic chip detectors, pulsed electrical chip burners (fuzz burners), main gearbox oil pressure and temperature switches, dual oil pumps, and freewheeling sprag clutches.

What is the fee for sitting the SACAA ATPL(H) exam?

The official SACAA examination fee is R450 per subject sitting as per SACAA Part 187 user fees (excluding optional test center admin fees).

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

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