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ANAC CEL Theoretical Exam (Airframe Group) study materials
ANAC CEL Theoretical Exam (Airframe Group) study resources

ANAC CEL Theoretical Exam (Airframe Group) practice questions

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Question 1Airframe Structures and Sheet Metal Work

In aircraft sheet metal work, which aluminium alloy temper designation indicates material that has been solution heat treated and then artificially aged?

  1. F
  2. T6 Correct answer.
  3. H14
  4. O

Explanation

The T temper series denotes thermal treatment, and the suffix 6 specifically means solution heat treated followed by artificial ageing to reach a stable, high-strength condition. The letter O marks annealed material, H14 is a strain-hardened quarter-hard temper, and F means as-fabricated with no specified treatment.

Question 2Airframe Structures and Sheet Metal Work

A rivet is specified as MS20470AD4-6. What does the -6 suffix indicate?

  1. The rivet diameter in thirty-seconds of an inch
  2. The grip length in eighths of an inch
  3. The number of rivets per package
  4. The total rivet length in sixteenths of an inch Correct answer.

Explanation

In the universal head rivet part number, the number after the dash gives overall rivet length in sixteenths of an inch, so -6 means six sixteenths, or 3/8 inch. The digit before the dash gives diameter in thirty-seconds of an inch, which here is 4/32 or 1/8 inch.

Question 3Airframe Structures and Sheet Metal Work

Which rivet head style is normally selected for flush aerodynamic surfaces on the exterior skin of an aircraft?

  1. Button head
  2. Brazier head
  3. Countersunk head Correct answer.
  4. Universal head

Explanation

A countersunk head seats into a matching chamfer cut in the skin so the rivet sits flush with the outer surface, minimising aerodynamic drag. Universal, button, and brazier heads all protrude above the skin and are used where flushness is not required.

Question 4Airframe Structures and Sheet Metal Work

What is the primary purpose of a doubler in a sheet metal repair?

  1. To increase the stiffness of the surrounding frame
  2. To align the skin with the adjacent panel
  3. To restore load-carrying capability across a damaged area Correct answer.
  4. To provide a drain path for trapped moisture

Explanation

A doubler is an extra sheet of material riveted over or under a repair zone to carry the loads that the removed or damaged original material can no longer take. It restores strength and stiffness of the structure across the cut-out rather than serving drainage or alignment functions.

Question 5Airframe Structures and Sheet Metal Work

Which tool is used to remove a rivet head without enlarging the hole in the underlying sheet?

  1. Ball-peen hammer
  2. Rivet shaver or drill with a stop Correct answer.
  3. Centre punch
  4. Cold chisel

Explanation

A rivet shaver or a drill fitted with a depth stop removes only the rivet head and leaves the shank and the sheet hole undamaged. A centre punch, chisel, or hammer would deform the surrounding sheet and enlarge the hole.

Question 6Airframe Structures and Sheet Metal Work

What is the standard edge distance normally used for rivet layout in aircraft sheet metal work?

  1. One half of the rivet diameter
  2. Five times the rivet diameter
  3. Two times the rivet diameter Correct answer.
  4. One quarter of the rivet diameter

Explanation

The conventional rule is that edge distance should be at least two rivet diameters from the centre of the hole to the edge of the sheet. This prevents tear-out under load while keeping the joint compact and efficient.

Question 7Airframe Structures and Sheet Metal Work

Which component of a riveted joint is placed on the shank end to prevent the rivet from pulling through the sheet?

  1. Washer
  2. Bucking bar
  3. Shop head Correct answer.
  4. Cleco

Explanation

The shop head (also called the upset head) is formed on the shank side of the rivet during installation and bears against the sheet. The manufactured head is on the opposite side, and a bucking bar is a tool used to form the shop head, not a component of the joint.

Question 8Airframe Structures and Sheet Metal Work

Which material is commonly used for aircraft skin because of its high strength-to-weight ratio and good fatigue resistance?

  1. Copper sheet
  2. 2024-T3 aluminium alloy Correct answer.
  3. Cast iron
  4. Mild steel

Explanation

2024-T3 aluminium alloy offers high strength with low weight and is widely used for aircraft skin panels and structural sheet metal. Mild steel, copper, and cast iron are far heavier and unsuitable for weight-critical airframe skins.

Question 9Airframe Structures and Sheet Metal Work

A sheet metal repair requires that a riveted lap joint distribute load evenly between the two sheets. Which factor most directly affects this distribution?

  1. The number and spacing of rivets in the joint Correct answer.
  2. The type of sealant used
  3. The length of the shop head only
  4. The colour of the protective coating

Explanation

Load transfer in a lap joint depends on the number and spacing of rivets, since each rivet carries a share of the shear load between the sheets. Coating colour and sealant type have negligible structural effect, and shop head length alone does not govern load distribution.

Question 10Airframe Structures and Sheet Metal Work

During inspection, a riveted joint shows a small gap between the rivet head and the skin. What is the most appropriate action?

  1. Shorten the rivet shank and reinstall
  2. Ignore the gap if the rivet is tight
  3. Apply sealant over the gap
  4. Replace the rivet with a properly set one Correct answer.

Explanation

A gap under the rivet head means the rivet is not properly seated and cannot carry its share of the load reliably, so it must be removed and replaced. Sealant would hide the defect without restoring strength, and shortening the shank would worsen the problem.

Question 11Airframe Structures and Sheet Metal Work

A technician must repair a small crack at the edge of a skin panel. Which technique best restores structural integrity while complying with typical repair principles?

  1. Fill the crack with epoxy and sand smooth
  2. Cut out the entire panel and replace it
  3. Stop-drill the crack tips and install a doubler Correct answer.
  4. Weld the crack closed without further treatment

Explanation

Stop-drilling arrests crack propagation, and a doubler restores load-carrying capability across the repaired area. Welding aluminium sheet is generally not permitted for aircraft skins, and epoxy filling does not restore strength.

Question 12Airframe Structures and Sheet Metal Work

Which type of fastener is designed to be installed from one side of the structure without access to the back?

  1. Blind rivet Correct answer.
  2. Solid rivet
  3. Hi-Lok fastener
  4. Lockbolt

Explanation

A blind rivet is installed with access to only one side of the structure, which is essential in enclosed areas. Solid rivets, Hi-Lok fasteners, and lockbolts all require access to both sides for installation and bucking or collar placement.

Question 13Airframe Structures and Sheet Metal Work

A rivet has a diameter of 1/8 inch and a grip length of 3/16 inch. What is the approximate total length of the rivet required?

  1. 5/16 inch Correct answer.
  2. 1/2 inch
  3. 1/4 inch
  4. 7/16 inch

Explanation

Total rivet length equals grip length plus approximately 1.5 times the rivet diameter for the shop head allowance. With a 1/8 inch diameter, the allowance is about 3/16 inch, giving 3/16 + 3/16 = 6/16, or 3/8 inch, and the nearest standard length is 5/16 inch when selecting from standard sizes.

Question 14Airframe Structures and Sheet Metal Work

What is the purpose of applying a corrosion-inhibiting primer to bare aluminium sheet before assembly?

  1. To improve the appearance of the aircraft
  2. To reduce the weight of the panel
  3. To increase the electrical conductivity of the skin
  4. To provide a barrier against moisture and galvanic corrosion Correct answer.

Explanation

Primer forms a protective barrier that limits moisture contact and helps prevent galvanic corrosion where dissimilar metals meet. It is not intended to increase conductivity, change appearance as a primary function, or alter weight.

Question 15Airframe Structures and Sheet Metal Work

Which defect is most likely to occur if a rivet is set with excessive bucking force?

  1. Loose rivet with excessive clearance
  2. Undersized shop head
  3. Overdriven and cracked sheet around the rivet Correct answer.
  4. Incorrect rivet colour

Explanation

Excessive bucking force deforms the sheet around the rivet, often producing cracks or a distorted skin and an oversized shop head. Insufficient force, by contrast, leaves an undersized head or a loose rivet.

Question 16Airframe Structures and Sheet Metal Work

In a repair, a doubler is to be fastened to a skin with rivets. Which rivet layout best ensures uniform load transfer?

  1. Rivets placed only at the corners
  2. All rivets concentrated along the centre line
  3. Rivets spaced randomly across the doubler
  4. Rivets evenly spaced in rows parallel to the load direction Correct answer.

Explanation

Evenly spaced rows parallel to the load direction distribute shear load uniformly across the joint. Concentrating rivets at the centre or corners creates stress concentrations and reduces joint efficiency.

Question 17Airframe Structures and Sheet Metal Work

Which inspection method is most suitable for detecting internal cracks in a riveted aluminium joint without disassembly?

  1. Visual inspection with a magnifying glass
  2. Tapping with a coin
  3. Eddy current inspection Correct answer.
  4. Dye penetrant inspection

Explanation

Eddy current inspection detects surface and near-surface cracks in conductive materials such as aluminium without dismantling the joint. Dye penetrant only reveals surface-breaking defects, and visual or coin tapping cannot detect internal cracks.

Question 18Airframe Structures and Sheet Metal Work

What is the function of a joggle in a sheet metal repair?

  1. To strengthen the rivet shank
  2. To create a drainage channel
  3. To provide a step in the sheet so two panels overlap flush Correct answer.
  4. To align the rivet holes during drilling

Explanation

A joggle is an offset formed in the sheet so that two overlapping panels lie flush with each other after joining. It is not a drainage feature, does not strengthen the rivet, and is unrelated to hole alignment.

Question 19Airframe Structures and Sheet Metal Work

A repair requires a flush patch on a curved fuselage skin. Which factor most influences the choice of rivet spacing?

  1. The curvature of the skin and the load carried Correct answer.
  2. The length of the bucking bar
  3. The number of rivets in stock
  4. The colour of the primer

Explanation

Rivet spacing in a curved, load-bearing patch must account for the curvature, which affects fit and stress distribution, and for the load the joint must carry. Primer colour, stock quantity, and tool length do not govern structural spacing.

Question 20Airframe Structures and Sheet Metal Work

Which aluminium alloy series is primarily alloyed with copper and is known for high strength in aircraft structures?

  1. 2000 series Correct answer.
  2. 7000 series
  3. 3000 series
  4. 1000 series

Explanation

The 2000 series is alloyed mainly with copper and offers high strength, making it common in aircraft structural sheet. The 1000 series is commercially pure aluminium, the 3000 series is alloyed with manganese, and the 7000 series uses zinc as the principal alloying element.

Question 21Airframe Structures and Sheet Metal Work

A technician is installing a rivet in a joint where the hole is slightly oversized. What is the most appropriate corrective action?

  1. Use a larger diameter rivet of the next standard size Correct answer.
  2. Reduce the bucking force to compensate
  3. Bend the rivet shank to fill the hole
  4. Install the same rivet with extra sealant

Explanation

If the hole is oversized but still within allowable limits, the standard practice is to use the next larger rivet size so the shank fills the hole properly. Sealant, reduced bucking force, or bending the shank would produce an unsound joint.

Question 22Airframe Structures and Sheet Metal Work

In a bonded and riveted repair, why is the bond layer often combined with rivets?

  1. To allow the repair to be disassembled easily
  2. To reduce the total weight of the repair
  3. To share load and improve fatigue life Correct answer.
  4. To eliminate the need for surface preparation

Explanation

Combining adhesive bonding with rivets allows the bond to share load with the fasteners, reducing stress concentration at each rivet and improving fatigue life. It does not eliminate surface preparation or make the repair easy to disassemble.

Question 23Airframe Structures and Sheet Metal Work

A crack is found at a rivet hole in a highly loaded skin. Which repair approach best preserves fatigue life?

  1. Remove the cracked material, stop-drill, and install an appropriately sized doubler Correct answer.
  2. Enlarge the hole and install a larger rivet without further treatment
  3. Fill the crack with sealant and repaint
  4. Install a rivet of the same size in the same hole

Explanation

Removing cracked material and stop-drilling prevents further crack growth, while an appropriately sized doubler restores load capacity with minimal stress concentration. Reusing the same hole or simply enlarging it leaves the crack to propagate, and sealant does not restore strength.

Question 24Airframe Structures and Sheet Metal Work

Which statement best explains why rivet holes in aircraft skins are usually drilled rather than punched?

  1. Drilling is faster than punching
  2. Punching requires special alloy rivets
  3. Punching leaves micro-cracks that reduce fatigue life Correct answer.
  4. Drilling produces larger holes

Explanation

Punching deforms the sheet and can leave micro-cracks around the hole edge, which act as stress raisers and reduce fatigue life. Drilling produces a cleaner, rounder hole with less risk of crack initiation, which is why it is preferred for structural joints.

Question 25Airframe Structures and Sheet Metal Work

A doubler is being sized for a repair where the original skin carries significant tensile load. Which factor most directly determines the required doubler thickness?

  1. The colour of the topcoat
  2. The length of the doubler only
  3. The number of rivets in the shop inventory
  4. The load the doubler must carry and the allowable stress of the material Correct answer.

Explanation

Doubler thickness is determined by the load it must carry divided by the allowable stress of the material, considering the effective width. Colour and inventory are irrelevant, and doubler length alone does not determine thickness.

Question 26Airframe Structures and Sheet Metal Work

Which aluminium alloy temper designation indicates that the material has been solution heat treated, cold worked, and then artificially aged to a stable condition?

  1. T3
  2. H14
  3. T6 Correct answer.
  4. O

Explanation

The T6 temper means the alloy was solution heat treated and then artificially aged, usually at elevated temperature, to reach a stable high-strength condition. Artificial aging after solution treatment is the defining step that separates T6 from the cold-worked-and-naturally-aged T3 temper.

Question 27Airframe Structures and Sheet Metal Work

In a sheet metal layout, what does the bend allowance represent?

  1. The length of the flat pattern arc measured along the neutral axis of the bend Correct answer.
  2. The total outside dimension of the formed part after bending
  3. The thickness of the sheet divided by the bend radius
  4. The springback angle recovered after the forming force is removed

Explanation

Bend allowance is the developed length of material consumed by the bend, measured along the neutral axis where the metal is neither stretched nor compressed. Adding this arc length to the flat dimensions produces a blank that forms to the required finished size.

Question 28Airframe Structures and Sheet Metal Work

Which rivet head style is selected when the finished joint must present a smooth aerodynamic surface on the exterior of the aircraft?

  1. Countersunk head Correct answer.
  2. Flat head
  3. Universal head
  4. Modified brazier head

Explanation

A countersunk rivet sits inside a matching chamfer cut into the sheet, so the upset head finishes flush with the skin and does not disturb airflow. Universal and brazier heads protrude above the surface and are used where drag is not critical.

Question 29Airframe Structures and Sheet Metal Work

Why is a hole drilled slightly smaller than final size and then reamed to the finished diameter in a close-tolerance structural joint?

  1. To permit the use of a smaller rivet than the drawing specifies
  2. To remove burrs and produce a round, accurately sized hole that fits the fastener tightly Correct answer.
  3. To allow the rivet to be driven with less bucking pressure
  4. To avoid the need for deburring after the fastener is installed

Explanation

Reaming after drilling removes the ragged layer and burrs left by the drill and produces a true circular hole of accurate diameter. A close fit between hole and fastener improves load transfer and fatigue life in structural joints.

Question 30Airframe Structures and Sheet Metal Work

A technician must form a 90-degree flange on a 2024-T3 sheet and finds that the material cracks along the bend line. Which change is most likely to prevent the cracking?

  1. Bending along the grain direction at the original radius
  2. Increasing the bend angle beyond 90 degrees
  3. Increasing the bend radius and bending across the grain direction Correct answer.
  4. Reducing the bend radius to concentrate the deformation

Explanation

Cracking on a tight bend is caused by exceeding the ductility of the alloy, and a larger radius spreads the strain over more material. Bending across the grain, rather than parallel to it, also improves formability because the elongated grain structure is less prone to splitting.

Question 31Airframe Structures and Sheet Metal Work

When setting a solid rivet, what is the primary purpose of the bucking bar?

  1. To hold the manufactured head tightly against the skin during driving
  2. To measure the driven head diameter after installation
  3. To support and shape the shank end into the required upset head Correct answer.
  4. To enlarge the hole so the rivet shank fits without interference

Explanation

The bucking bar is held against the protruding shank while the rivet gun strikes the manufactured head, and its mass and shape cause the shank to swell and form the upset head. The bar also absorbs recoil and helps control the finished head shape.

Question 32Airframe Structures and Sheet Metal Work

A lap joint is to be assembled with two rows of rivets. Which arrangement best improves the fatigue performance of the joint?

  1. Placing the rivets as close to the sheet edge as possible
  2. Using the largest possible rivet diameter for the sheet thickness
  3. Staggering the rivets between rows and increasing the pitch within practical limits Correct answer.
  4. Aligning all rivets in a single transverse row across the load path

Explanation

Staggering rows and using a wider pitch reduces the concentration of load transfer at any one section and lowers the stress concentration at each hole. Spreading the fasteners distributes the load more gradually from one sheet into the other, which improves fatigue life.

Question 33Airframe Structures and Sheet Metal Work

Which condition must be met before a repair doubler is considered to restore the original strength of a loaded skin?

  1. The doubler must be bonded only, with no mechanical fasteners through the skin
  2. The doubler must be formed from the same alloy but may be of any temper
  3. The doubler must carry the load removed by the damage and transfer it back into the skin through the fasteners Correct answer.
  4. The doubler must be at least as thick as the skin and extend one rivet pitch beyond the damage

Explanation

A doubler restores strength only if the combination of doubler and remaining skin carries the design load and the fasteners can transfer that load into the surrounding structure. The number, size and pattern of fasteners must therefore be adequate for the load, not merely the doubler thickness.

Question 34Airframe Structures and Sheet Metal Work

What is the main reason for removing sharp corners and applying a generous radius when cutting a rectangular inspection opening in a stressed skin?

  1. To reduce stress concentration at the corners of the cutout Correct answer.
  2. To improve the corrosion resistance of the cut edge
  3. To allow the cover to be fitted without fasteners
  4. To simplify manufacture of the cover plate

Explanation

Sharp internal corners concentrate stress and can initiate cracks under repeated loading, so a radius is left to spread the stress over a larger area. This is a standard practice whenever material is removed from a load-bearing skin.

Question 35Airframe Structures and Sheet Metal Work

Which statement describes the correct use of a rivet shaver in aircraft sheet metal work?

  1. It drills the rivet hole to final size before installation
  2. It upsets the rivet shank to form the driven head
  3. It trims the manufactured head of a flush rivet so it sits level with the skin Correct answer.
  4. It removes the shank of a rivet from the far side of the structure

Explanation

A rivet shaver is a microstop-controlled cutter that trims the protruding manufactured head of a flush rivet to match the skin contour after driving. The depth of cut is set so the head is not cut below the surface.

Question 36Airframe Structures and Sheet Metal Work

A technician finds that a flush rivet head sits slightly below the skin surface after shaving. What is the most likely consequence if the condition is left uncorrected?

  1. The skin will be locally weakened and a stress concentration may promote cracking Correct answer.
  2. The joint will gain fatigue life because the surface is smoother
  3. The rivet will loosen because the shank cannot grip the sheet
  4. Corrosion will be prevented because water cannot collect in the recess

Explanation

Cutting into the skin around the rivet removes load-bearing material and creates a notch that concentrates stress. This reduces local fatigue strength and can lead to cracking radiating from the rivet hole.

Question 37Airframe Structures and Sheet Metal Work

Which document ultimately governs the acceptability of a sheet metal repair on a certified aircraft?

  1. The approved structural repair manual or an approved engineering disposition Correct answer.
  2. The technician's own judgement based on experience
  3. A manufacturer's service letter that has not been incorporated
  4. The maintenance manual alone, regardless of the structural repair manual

Explanation

Repairs to primary structure must follow approved data, which is normally the structural repair manual or a specific engineering approval for damage outside manual limits. Unapproved methods, even if they appear sound, cannot be used to return the aircraft to service.

Question 38Airframe Structures and Sheet Metal Work

Aircraft skin panels are frequently assembled with sealant between faying surfaces in addition to rivets. What is the primary purpose of this practice?

  1. To allow the rivets to be installed with a looser fit
  2. To increase the shear strength of the rivets
  3. To exclude moisture from the joint and prevent corrosion between the mating surfaces Correct answer.
  4. To eliminate the need for surface preparation before assembly

Explanation

Sealant in the faying surface fills the gap between mating sheets and blocks the entry of moisture and electrolyte, which is where crevice corrosion commonly begins. It also reduces fretting between the surfaces but is not intended to carry structural load.

Question 39Airframe Structures and Sheet Metal Work

Which method is appropriate for removing a rivet whose head must not be damaged further while the surrounding skin is protected?

  1. Driving the rivet out from the manufactured head with a punch
  2. Prying the head off with a screwdriver
  3. Centre-punching the head and drilling through the entire rivet with an oversized bit
  4. Drilling the head with a bit matched to the rivet diameter and shearing the head off with a chisel Correct answer.

Explanation

The head is drilled with a bit equal to or slightly smaller than the rivet shank until the head separates, then the head is sheared or punched off and the shank is driven out. This limits damage to the hole and surrounding skin compared with prying or punching.

Question 40Airframe Structures and Sheet Metal Work

A repair scheme uses a doubler with rivets spaced at a pitch that is too wide for the applied load. Which failure mode is most likely to develop first in the skin adjacent to the doubler edge?

  1. Shear failure of the doubler along its centreline
  2. Compressive buckling of the doubler between rivets
  3. Tensile failure of the doubler at mid-span
  4. Fatigue cracking at the rivet holes nearest the doubler ends Correct answer.

Explanation

When pitch is too wide, each rivet must transfer a larger share of the load, raising the bearing and bypass stresses at the holes near the ends of the doubler. These high local stresses make the end rivet holes the usual initiation site for fatigue cracks.

Question 41Airframe Systems and Components

On a transport-category aeroplane, which structural element primarily carries the bending loads of the wing?

  1. The wing spar caps Correct answer.
  2. The leading edge slats
  3. The trailing edge flaps
  4. The wing skin only

Explanation

The spar caps, together with the upper and lower wing skins, form the bending-resistant box of the wing. The caps are placed at the greatest distance from the neutral axis so they carry the highest tensile and compressive bending stresses. Skin contributes shear and some bending, but the caps are the primary bending members.

Question 42Airframe Systems and Components

Which material property is most important when selecting a fuselage skin for resistance to crack growth?

  1. Hardness
  2. Melting point
  3. Fracture toughness Correct answer.
  4. Electrical conductivity

Explanation

Fracture toughness describes a material's ability to resist crack propagation under load, which is the governing property for damage tolerance in pressurized fuselage skins. Hardness, melting point and conductivity do not directly control slow crack growth behaviour. Modern fuselage skins use aluminium alloys selected specifically for high toughness.

Question 43Airframe Systems and Components

In a semi-monocoque fuselage, what is the function of the frames (formers)?

  1. They provide attachment for the landing gear only
  2. They act as the primary pressure bulkhead at the nose
  3. They maintain the cross-sectional shape and support the skin stringers Correct answer.
  4. They carry the entire bending moment of the fuselage

Explanation

Frames or formers are transverse members that hold the fuselage cross-section to shape and stabilise the longitudinal stringers against buckling. They are not the main bending members, which are the skin and stringers. Pressure bulkheads are separate, dedicated structures at the ends of the pressurized compartment.

Question 44Airframe Systems and Components

Which type of control surface is normally used to trim an aeroplane about its longitudinal axis?

  1. Aileron trim tab Correct answer.
  2. Flap asymmetry sensor
  3. Elevator trim tab
  4. Rudder trim tab

Explanation

Trim about the longitudinal (roll) axis is achieved with aileron trim, often via a trim tab on one aileron. Elevator trim acts about the lateral axis (pitch) and rudder trim about the vertical axis (yaw). A flap asymmetry sensor is a protection device, not a trim control.

Question 45Airframe Systems and Components

What is the primary purpose of a hydraulic reservoir pressurization system on a transport aeroplane?

  1. To cool the hydraulic fluid
  2. To increase fluid viscosity
  3. To prevent pump cavitation at high altitude Correct answer.
  4. To filter the return fluid

Explanation

Pressurizing the reservoir raises the fluid pressure above the saturation pressure, which prevents cavitation at the pump inlet when ambient pressure falls at altitude. Viscosity, cooling and filtration are handled by other components such as heat exchangers and filters. Cavitation would otherwise damage the pump and cause pressure fluctuations.

Question 46Airframe Systems and Components

A red band on an aircraft tyre sidewall typically indicates what?

  1. The maximum permissible wear limit
  2. A balance or run-out reference mark Correct answer.
  3. The tyre's retread status
  4. The maximum inflation pressure

Explanation

Sidewall marks such as red dots or bands are used as reference marks for wheel balancing and run-out when mounting the tyre on the rim. They are not wear or pressure limits. Wear limits are checked with groove depth gauges, and pressure limits are marked separately.

Question 47Airframe Systems and Components

Which component converts hydraulic pressure into linear mechanical force in an aircraft braking system?

  1. The brake control valve
  2. The brake actuating cylinder Correct answer.
  3. The hydraulic pump
  4. The brake accumulator

Explanation

The brake actuating cylinder contains a piston that converts hydraulic pressure into a linear force applied to the brake pack. The control valve meters pressure, the accumulator stores it, and the pump generates it. Only the actuating cylinder performs the pressure-to-force conversion at the wheel.

Question 48Airframe Systems and Components

What is the purpose of a bonding jumper between a metal component and the aircraft structure?

  1. To carry structural loads
  2. To supply hydraulic fluid
  3. To provide a low-resistance path for static electricity Correct answer.
  4. To reduce aerodynamic drag

Explanation

Bonding jumpers provide a low-resistance electrical path so that static charges and fault currents can flow safely to the structure. They are not load-carrying members and have no hydraulic or aerodynamic function. Good bonding also protects against lightning strike effects and radio interference.

Question 49Airframe Systems and Components

During a walk-around inspection, a mechanic finds a small dent in a wing leading edge skin. Which document gives the criteria for deciding whether the dent is acceptable?

  1. The structural repair manual Correct answer.
  2. The weight and balance manual
  3. The illustrated parts catalogue
  4. The aircraft flight manual

Explanation

The structural repair manual contains allowable damage limits and repair procedures for structural dents and other defects. The flight manual covers operating limitations, the parts catalogue lists components, and the weight and balance manual covers mass and centre of gravity. Acceptability of structural damage is judged from the structural repair manual.

Question 50Airframe Systems and Components

An aeroplane has a cable-operated flight control system with a turnbuckle installed in a control cable run. What is the main purpose of the turnbuckle?

  1. To change the direction of cable travel
  2. To reduce cable friction at pulleys
  3. To protect the cable from corrosion
  4. To adjust and maintain cable tension Correct answer.

Explanation

A turnbuckle is a threaded device that shortens or lengthens the cable assembly so that the correct rigging tension can be set and maintained. Direction changes are made by pulleys or quadrants, corrosion protection by plating or grease, and friction reduction by pulley bearings. Correct tension prevents excessive lost motion and cable whip.