CAAS SAR-66 AML Module 11 — Turbine Aeroplane Aerodynamics, Structures and Systems

What aerodynamic phenomenon occurs when an aircraft accelerates past its critical Mach number (Mcr)?

• AAirflow over the upper wing surface accelerates to supersonic speed, forming local shock…
• BThe entire airframe instantly experiences supersonic flow from nose to tail.
• CInduced drag drops to zero as boundary layer separation is entirely suppressed.
• DThe center of pressure moves rapidly forward toward the leading edge.

What is the primary function of wing sweepback on high-speed turbine aeroplanes?

• AIt delays the onset of critical Mach number by reducing the effective spanwise curvature…
• BIt increases low-speed maximum lift coefficient (CLmax) during takeoff and landing.
• CIt eliminates the formation of wingtip vortices completely during cruise flight.
• DIt reduces structural wing weight by increasing spar root depth.

Which aerodynamic device is designed specifically to re-energize the boundary layer and delay airflow separation at high angles of attack?

• AVortex generators
• BTrailing-edge trim tabs
• CMach trim actuators
• DGround spoilers

What is 'Mach Tuck' and what causes it during high-subsonic flight?

• AA nose-down pitching tendency caused by the aft movement of the center of pressure as sho…
• BA nose-up pitching moment resulting from loss of downwash over the tailplane at high angl…
• CA rapid uncommanded yaw angle caused by asymmetric shock wave detachment on swept wingtip…
• DA high-frequency structural vibration caused by flutter in trailing-edge control surfaces.

How do Krueger flaps differ from leading-edge slats in their deployment mechanism and aerodynamic operation?

• AKrueger flaps hinge forward and down from the lower leading edge, whereas slats extend fo…
• BKrueger flaps open slots for high-pressure air to flow over the lower wing surface, where…
• CKrueger flaps are used exclusively at high Mach numbers for wave drag reduction, whereas…
• DKrueger flaps are variable-camber trailing-edge devices, while slats are rigid leading-ed…

In a swept-wing jet transport, why is spanwise boundary layer flow problematic at high angles of attack, and how is it mitigated?

• ASpanwise flow thickens the boundary layer at the wingtips leading to premature tip stall;…
• BSpanwise flow concentrates boundary layer air at the wing root causing premature root sta…
• CSpanwise flow creates reverse flow over the elevator; anti-servo tabs are installed on th…
• DSpanwise flow forces air outward into the engine intakes; intake bypass doors are used to…

Which type of structural classification applies to airframe components whose failure would result in catastrophic loss of the aeroplane?

• APrimary structure
• BSecondary structure
• CTertiary structure
• DNon-load-bearing structure

What defines a 'fail-safe' structural design philosophy in transport category aircraft?

• AIncorporating redundant load paths so that if one member fails, adjacent members safely s…
• BDesigning components with infinite fatigue life so they never crack or experience fatigue…
• CReplacing all metallic structural elements with composite honeycomb panels that resist al…
• DAllowing primary structural components to deform plastically under normal limit loads wit…

Which form of corrosion occurs in composite-to-metal joints when carbon fiber reinforced plastic (CFRP) comes into direct contact with aluminum alloys?

• AGalvanic corrosion
• BIntergranular corrosion
• CStress corrosion cracking
• DFretting corrosion

What is the key characteristic of 'damage tolerant' structural design mandated for modern turbine aircraft under SAR-25 / CS-25?

• AThe structure is evaluated to show that fatigue cracks, manufacturing defects, or corrosi…
• BThe structure relies on mandatory replacement of components at strict life limits regardl…
• CThe airframe is designed to absorb ground bird strikes without experiencing any elastic d…
• DAll fuselage skin panels must be manufactured without lap joints or fastener holes to pre…

During structural repairs of pressurized fuselage skin, why are teardrop-shaped or oval doublers preferred over rectangular doublers with sharp 90-degree corners?

• ATo avoid severe stress concentrations at sharp corners that induce premature fatigue crac…
• BTo ensure uniform aerodynamic laminar flow across the outer fuselage boundary layer durin…
• CTo reduce the number of blind rivets required along the circumferential repair lap joint.
• DTo permit flush countersinking of doubler edges without dimpling the underlying stringers.

In a semi-monocoque fuselage, what primary function do longerons perform compared to stringers?

• ALongerons are heavy primary longitudinal members that carry major bending loads and suppo…
• BLongerons are light circumferential rings that maintain fuselage cross-sectional shape un…
• CLongerons are flexible composite ribs that prevent skin oil-canning between bulkheads.
• DLongerons are vertical floor beams that support passenger seat tracks and cargo floor loa…

During a heavy maintenance structural symmetry check, a technician measures distance from the tailcone datum to the left wingtip datum as 15,240 mm, and to the right wingtip datum as 15,258 mm. The Structural Repair Manual (SRM) specifies a maximum symmetry tolerance of 12 mm. What is the status of this airframe?

• AOut of symmetry tolerance by 6 mm; the airframe requires structural realignment investiga…
• BWithin symmetry tolerance; the 18 mm difference is divided by 2 giving 9 mm deviation.
• COut of symmetry tolerance by 18 mm; the entire wing root spar must be replaced immediatel…
• DWithin symmetry tolerance; SRM limits apply only to diagonal nose-to-tail measurements.

What is the main structural function of wing rib stations in a multi-spar cantilever wing box?

• ATo maintain aerofoil contour, transfer aerodynamic skin loads to spars, and prevent skin/…
• BTo absorb engine thrust loads and transfer them directly into the fuselage pressure cabin.
• CTo act as fluid-tight bulkheads that isolate hydraulic fluid from fuel storage tanks.
• DTo damp out high-frequency aerodynamic flutter by acting as mechanical mass balances.

Which tailplane configuration is specifically designed to clear wing wake turbulence and engine exhaust wash at high angles of attack?

• AT-tail configuration
• BLow-set horizontal stabiliser
• CV-tail butterfly configuration
• DCanard forward stabiliser

What is the purpose of 'wing incidence angle' set by the airframe manufacturer at the wing root?

• ATo allow the fuselage to fly at an optimum low-drag pitch attitude during cruise while th…
• BTo ensure that the wingtips stall before the wing root during high angle of attack maneuv…
• CTo compensate for asymmetric propeller slipstream on multi-engine turbine aircraft.
• DTo prevent wing structural twist during high Mach number emergency descents.

When verifying wing dihedral angle using a precision alignment board and spirit level over a 2,000 mm spanwise measurement distance, a vertical height rise of 104.7 mm is recorded. What is the calculated dihedral angle?

• A3.0 degrees
• B5.2 degrees
• C1.5 degrees
• D6.0 degrees

In a bootstrap Air Cycle Machine (ACM) pressurisation system, what primary function does the secondary heat exchanger perform?

• AIt removes the heat of compression generated by the ACM centrifugal compressor before air…
• BIt preheats engine bleed air prior to entering the high-pressure primary heat exchanger.
• CIt condenses moisture directly out of the cabin recirculated air prior to water separator…
• DIt cools the ACM lubricating oil sump using ram air during high-altitude cruise.

What is the main function of the cabin pressurisation Outflow Valve (OFV)?

• ATo regulate cabin altitude, rate of climb/descent, and differential pressure by controlli…
• BTo automatically inject high-pressure engine bleed air directly into the cabin when cabin…
• CTo shut off all incoming pack air in the event of cabin smoke detection.
• DTo equalize pressure between the main passenger cabin and lower cargo holds during rapid…

An aeroplane is cruising at FL350 where ambient atmospheric pressure is 3.46 psi. The cabin pressurisation controller maintains a cabin altitude of 8,000 ft, where atmospheric pressure is 10.92 psi. What is the cabin differential pressure (Pdiff)?

• A7.46 psi
• B14.38 psi
• C8.50 psi
• D3.46 psi

What safety feature prevents cabin pressure from exceeding structural design limits if the automatic outflow valve fails fully closed?

• ASpring-loaded positive pressure relief valves that open mechanically when maximum Pdiff i…
• BNegative pressure relief valves that open inward when ambient pressure exceeds cabin pres…
• CDecompression dado panels that blow open between cabin zones.
• DAutomatic pack flow control valves that increase air inlet flow to purge excess pressure.

Why is a water separator equipped with a coalescer bag and anti-ice bypass loop in an air cycle environmental system?

• ATo coalesce microscopic moisture droplets into larger drops for mechanical removal and by…
• BTo convert condensed moisture into superheated steam prior to cabin distribution.
• CTo prevent engine oil mist from entering the cabin air ducts by chemical absorption.
• DTo cool the water separator housing using high-pressure turbine exhaust gas.

What is the primary operational objective of the cabin altitude 'ditch' switch on a modern transport aeroplane?

• ATo close all fuselage underwater openings, including outflow valves, emergency ram air in…
• BTo immediately dump all cabin pressure to equalize interior and exterior water pressure b…
• CTo inflate external flotation bags mounted inside the wing root fairings.
• DTo activate high-capacity bilge pumps powered by the essential DC battery bus.

If an aircraft climbs from sea level to 30,000 ft in 15 minutes while the pressurisation controller maintains a constant cabin rate of climb of 500 ft/min, what is the cabin altitude when the aircraft reaches 30,000 ft?

• A7,500 ft
• B8,000 ft
• C5,000 ft
• D10,000 ft

In an Electronic Flight Instrument System (EFIS), which unit processes raw sensor data from ADIRUs and navigation receivers to generate visual display formats for the PFD and ND?

• ASymbol Generator (SG) / Display Electronic Unit (DEU)
• BPitot-Static Air Data Computer (ADC)
• CFlight Management Computer (FMC)
• DInertial Reference Unit (IRU)

What is the function of the Mach/Airspeed Indicator's maximum operating speed (VMO/MMO) pointer ('barber pole')?

• AIt dynamically indicates the maximum permissible airspeed/Mach limit, adjusting automatic…
• BIt displays the minimum unstick speed (VMU) during takeoff rotation.
• CIt shows the target cruise airspeed calculated by the autothrottle system.
• DIt indicates the stall warning speed (VS1G) as fuel weight burns off.

Which component of an Air Data Inertial Reference System (ADIRS) provides angular rate and acceleration data without any moving mechanical gyroscopes?

• ARing Laser Gyro (RLG) or Fiber Optic Gyro (FOG)
• BMechanical iron-rotor directional gyro
• CFlux valve magnetic detector
• DSynchronous synchro-resolver motor

In an Autopilot / Flight Director System (AFDS), what is the function of the control wheel steering (CWS) mode?

• AIt allows the pilot to maneuver the aircraft manually through force sensors on the contro…
• BIt locks the control column mechanically while the FMC executes automatic Category III la…
• CIt disconnects all electrical servos and reverts flight controls to manual elevator trim…
• DIt automatically steers the nose gear on the ground during high-speed taxi turnoffs.

What TCAS II resolution advisories (RA) are provided to the flight crew when an intruder aircraft presents an immediate collision threat?

• AVertical avoidance maneuvers (climb or descend command rate indications).
• BHorizontal turn commands (left or right heading change degrees).
• CAutomatic engine throttle reduction commands to increase longitudinal spacing.
• DAutomatic flap deployment commands to reduce stall margin.

In a pitot-static system, what occurs if the main pitot tube drain hole and inlet become completely blocked by ice in flight during a climb?

• AThe indicated airspeed will erroneously increase as altitude increases, behaving like an…
• BThe indicated airspeed will drop to zero immediately.
• CThe altimeter will freeze at the altitude where the blockage occurred.
• DThe vertical speed indicator (VSI) will read a continuous maximum rate of descent.

What type of AC electrical power supply standard is utilized on modern commercial transport aeroplanes?

• A115V AC, 3-phase, 400 Hz constant frequency.
• B230V AC, single-phase, 50 Hz variable frequency.
• C12V DC, negative ground, 60 Hz.
• D440V AC, 3-phase, 1000 Hz.

A 28V DC aircraft bus supplies three parallel loads: Position Lights (140 W), Pitot Probe Heater (560 W), and Avionics Bus (840 W). What is the total current draw on the 28V DC bus?

• A55 Amperes
• B45 Amperes
• C70 Amperes
• D28 Amperes

What primary component converts 115V AC main generator power into 28V DC power for charging batteries and powering DC essential buses?

• ATransformer Rectifier Unit (TRU)
• BStatic Inverter
• CIntegrated Drive Generator (IDG)
• DConstant Speed Drive (CSD)

What is the function of the Bus Tie Breaker (BTB) in a split-bus AC electrical distribution architecture?

• AIt allows one generator to power both main AC buses if a generator fails, while keeping b…
• BIt automatically disconnects non-essential galley loads during engine start.
• CIt connects the APU generator in parallel with engine generators without frequency synchr…
• DIt trips open to isolate the battery from the hot battery bus during thermal runaway.

Why is an Integrated Drive Generator (IDG) equipped with a mechanical disconnect mechanism operated from the flight deck?

• ATo physically uncouple the CSD drive shaft from the engine accessory gearbox in case of s…
• BTo allow the pilot to manually adjust CSD governor output speed during high-altitude crui…
• CTo re-engage the generator in flight once CSD oil temperature cools down.
• DTo switch generator output from 115V AC to 28V DC manually.

An emergency 24V Nickel-Cadmium battery has a rated capacity of 40 Ampere-hours (Ah). Following total AC power loss, the emergency DC bus draws a constant load of 600 Watts at 24V DC. Assuming 80% usable battery capacity limit for safe avionics operation, how long will the battery support this emergency load?

• A76.8 minutes
• B96.0 minutes
• C60.0 minutes
• D120.0 minutes

What phenomenon occurs in aircraft Nickel-Cadmium (Ni-Cad) batteries if cell internal resistance drops during high-current charging, and how is it prevented?

• AThermal runaway; prevented by battery temperature sensors and constant-current/constant-v…
• BSulphation of plates; prevented by adding concentrated sulphuric acid electrolyte.
• CElectrolyte boiling due to positive plate growth; prevented by short-circuiting cell term…
• DCarbonation of separator felt; prevented by charging at 400 Hz AC voltage directly.

According to SAR-25 certification requirements for emergency equipment, how quickly must all passengers be capable of evacuating the aeroplane through active emergency exits?

• A90 seconds
• B60 seconds
• C120 seconds
• D180 seconds

What automatic deployment feature is built into passenger emergency evacuation slides on commercial transport aircraft doors?

• AThe slide girt bar is attached to floor fittings when armed, causing the slide to pull fr…
• BElectrical proximity switches detect door handle movement and fire pyrotechnic slide cutt…
• CCabin differential pressure blows the door outward, pulling an inflation lanyard attached…
• DThe slide is inflated continuously by low-pressure bleed air whenever passenger doors are…

What structural load factor rating must passenger seats and their floor attachment tracks satisfy under SAR-25 static/dynamic emergency landing conditions?

• A16g forward dynamic load factor.
• B9g forward dynamic load factor.
• C25g forward dynamic load factor.
• D6g forward dynamic load factor.

What is the function of cargo compartment restraint nets and barrier assemblies installed in lower deck cargo holds?

• ATo prevent bulk cargo and Unit Load Devices (ULDs) from shifting under ultimate flight/cr…
• BTo seal cargo bays hermetically against water leakage from the upper passenger cabin lava…
• CTo insulate cargo containers against sub-zero flight deck temperatures.
• DTo provide ground crew with safety handholds during container loading.

Which fire detection system utilizes a continuous sensing element containing a core wire embedded in a eutectic salt compound whose electrical resistance drops sharply when exposed to heat?

• AKidde continuous loop system
• BSystron-Donner pneumatic element loop
• COptical infrared flame detector
• DIonization smoke detector

What extinguishing agent is standard in fixed engine and APU fire extinguishing bottle systems on turbine aeroplanes?

• AHalon 1301 (Bromotrifluoromethane)
• BCarbon dioxide (CO2) dry ice powder
• CWater-glycol spray
• DSynthetic aqueous film-forming foam (AFFF)

How does a dual-loop engine fire detection system handle a fault when Loop A experiences a short circuit while Loop B remains fully functional?

• AThe fire detection computer isolates Loop A, issues a loop fault channel alert, and autom…
• BThe system immediately triggers a false master engine fire warning in the cockpit.
• CThe fire detection system shuts down both loops and automatically discharges fire bottle…
• DThe computer locks out all fire warnings until Loop A is manually grounded by ground crew.

What indication confirms that a fixed engine fire extinguishing bottle has discharged due to ambient over-temperature thermal relief on the ground?

• ARupture of a thermal relief safety disc discharging agent overboard through a red indicat…
• BIllumination of a yellow 'BOTTLE DISCH' light on the flight deck overhead panel without a…
• CPopping of the main battery circuit breaker on the P6 panel.
• DEjection of the amber engine fire handle lock pin.

Which cargo compartment fire protection method is mandated for Class C cargo holds on passenger transport aeroplanes?

• ABuilt-in smoke detection system and pilot-controlled fire suppression system operating fr…
• BManual access for crew members to enter with portable fire extinguishers during flight.
• CRelying entirely on starvation of oxygen by shutting off all cabin air recycling.
• DContinuous water deluge spray powered by the potable water system.

Which secondary flight control surfaces deploy symmetrically in flight to act as speed brakes, and asymmetrically to assist ailerons in roll control?

• ASpoilers / Lift dumpers
• BLeading-edge slats
• CTrailing-edge Fowler flaps
• DTrim tabs

What is the function of an anti-servo tab installed on a trailing edge of an all-moving tailplane (stabilator)?

• AIt moves in the same direction as the stabilator to increase aerodynamic stick forces and…
• BIt moves in the opposite direction to reduce control column forces to near zero.
• CIt deflects down only when flaps are extended to prevent tailplane stall.
• DIt locks the stabilator mechanically when autopilot is engaged.