21 Materials, Hardware & Drawings Practice Questions & Answers

1. 1. On an aircraft drawing, how is a hidden line — the line used to show an edge or contour that cannot be seen from the viewing position — drawn?

   • A.A thin line made up of alternating long and short dashes
   • B.A medium-weight line made up of short dashes evenly spaced✓ Answer
   • C.A thin, freehand wavy line drawn across the part
   • D.A thin line made up of one long dash followed by two short dashes

   A hidden line is a medium-weight line of short dashes that are evenly spaced, which is what lets the reader tell it apart at a glance from a centerline (thin, alternating long and short dashes) and a phantom line (thin, one long and two short dashes). Confusing the three changes which features you believe actually exist behind the visible surface; the wavy freehand line is a short-break line.

   Source: FAA-H-8083-30, Ch. 4 Aircraft Drawings, 'Lines and Their Meanings'Report a problem with this question

2. 2. A drawing shows the cross section of one particular part drawn off to the side of the main view, often at a larger scale than the rest of the drawing. What is this type of view called?

   • A.Half section
   • B.Removed section✓ Answer
   • C.Revolved section
   • D.Full section

   A removed section is drawn away from the view it is taken from, frequently enlarged, so that small internal detail can be shown clearly without crowding the main view. A revolved section is rotated in place on the view itself, a half section removes one quarter of the object to show inside and outside on one view, and a full section cuts entirely through the object.

   Source: FAA-H-8083-30, Ch. 4 Aircraft Drawings, 'Sectional Views'Report a problem with this question

3. 3. The title block of a drawing carries a blanket tolerance of ±.010 inch. A dimension on that same drawing is written 2.000 +.005 −.002. Which statement is correct?

   • A.The blanket tolerance governs, so the total tolerance is .020 inch
   • B.Both tolerances apply, so the part is acceptable at 2.015 inch
   • C.The blanket tolerance is added to the stated limits, giving .017 inch
   • D.The limits stated at the dimension override the blanket tolerance, and the total tolerance is .007 inch✓ Answer

   A blanket tolerance in the title block (which sits in the lower right corner of the print with the drawing number, part name, scale, and approvals) applies only to dimensions that do not state their own limits. Total tolerance is the full permissible variation, upper limit minus lower limit: 2.005 − 1.998 = .007 inch.

   Source: FAA-H-8083-30, Ch. 4 Aircraft Drawings, 'Title Block' and 'Tolerances'Report a problem with this question

4. 4. Which statement best describes a schematic diagram of an aircraft system?

   • A.It uses symbols to show the function of the system and the flow through it, without regard to the actual size, shape, or location of the components✓ Answer
   • B.It reduces the system to labeled rectangles that show only major units and how they relate
   • C.It shows the actual physical location, routing, and relative size of every component
   • D.It shows the parts of an assembly pulled apart but aligned along their axes of assembly

   A schematic is a functional drawing: it uses standard symbols to show what each component does and how fluid, air, or current flows through the system, which is why it is the diagram used for troubleshooting logic rather than for locating hardware. Physical routing and terminal locations come from an installation or wiring diagram, a block diagram shows only major units, and an exploded pictorial shows parts separated along their assembly axes.

   Source: FAA-H-8083-30, Ch. 4 Aircraft Drawings, 'Diagrams' (schematic, block, wiring, pictorial)Report a problem with this question

5. 5. Which statement is true about forming a flare on aircraft tubing?

   • A.The flare angle is unimportant provided a double flare is used
   • B.Aircraft flares are formed to 35°–37° to match AN/MS fittings, and a 45° automotive flare must never be substituted✓ Answer
   • C.A 45° automotive flare is acceptable on AN fittings as long as the tube is deburred and the nut is torqued to value
   • D.Aircraft flares are 45° and automotive flares are 37°, so an automotive tool is the correct choice

   AN/MS fitting cones are ground to the 35°–37° aircraft standard, so a 45° flare contacts the fitting on a narrow line instead of a full seating surface and will leak or crack under pressure and vibration. Note also that soft aluminum tubing (5052-O and 6061-T) in sizes 1/8 through 3/8 inch OD is given a double flare, which is more concentric and more resistant to shearing under nut torque.

   Source: FAA-H-8083-30, Ch. 9 Fluid Lines and Fittings, 'Flaring' (single and double flares, 35°–37° AN standard)Report a problem with this question

6. 6. After the sleeve of an MS flareless fitting has been preset, how is the nut tightened for final installation?

   • A.Finger tight only, and then safety wired to prevent backing off
   • B.To the same torque value published for a flared fitting of the same size
   • C.Finger tight, then exactly one full turn with a wrench
   • D.Run the nut down finger tight, then tighten 1/6 turn (one hex flat) past the point where it begins to bottom; if it leaks on test, one additional 1/6 turn is allowed, for 1/3 turn maximum✓ Answer

   The flareless sleeve seals by biting into the tube a controlled amount, so the installation is measured in turns past bottoming rather than in torque: 1/6 turn seats the sleeve, and a further 1/6 turn is the only correction permitted for a leak. Going beyond 1/3 turn total cuts too deeply into the tube wall and creates a fatigue point that can fail in service.

   Source: FAA-H-8083-30, Ch. 9 Fluid Lines and Fittings, 'Flareless Tube Fittings' (presetting and 1/6-turn installation)Report a problem with this question

7. 7. Why is flexible hose installed with 5 to 8 percent slack, and what does a lay line that spirals around the installed hose tell the mechanic?

   • A.Slack is left so the hose can be rerouted later, and the lay line only identifies the manufacturer
   • B.Hose shortens in length and grows in diameter when pressurized, so slack keeps it from being loaded in tension; a spiraled lay line means the hose is twisted and must be reinstalled✓ Answer
   • C.Slack allows for thermal growth of the end fittings, and a spiraled lay line is normal on any curved run
   • D.Slack allows for the hose stretching when pressurized, and the lay line marks the minimum bend radius

   A pressurized hose contracts in length (roughly up to 4 percent) while expanding in diameter, so a hose installed tight would be pulled into tension at its end fittings; 5 to 8 percent slack absorbs that movement plus vibration. The lay line is printed as a straight stripe along the hose, so if it winds around the hose after installation the hose is twisted, which weakens it and can back the fitting off under pressure.

   Source: FAA-H-8083-30, Ch. 9 Fluid Lines and Fittings, hose installation practices (slack and lay line)Report a problem with this question

8. 8. Electrochemical corrosion cannot proceed unless four conditions exist at the same time. Which set of four is required?

   • A.An acid, an alkali, moisture, and bare metal
   • B.An anode, a cathode, an electrolyte, and a conductive path between the anode and the cathode✓ Answer
   • C.Heat, oxygen, dissimilar metals, and tensile stress
   • D.Salt, humidity above 65 percent, a paint failure, and dissimilar metals

   Electrochemical corrosion is a battery: current leaves the anode (the metal that is consumed), passes through an electrolyte to the cathode, and returns through a metallic path. Remove any single element — seal out the electrolyte with paint or sealant, or insulate the metals so there is no conductive path — and the cell stops working, which is exactly how protective finishes and nonmetallic barriers prevent corrosion.

   Source: FAA-H-8083-30, Ch. 6 Cleaning and Corrosion Control, 'Types of Corrosion / electrochemical attack'Report a problem with this question

9. 9. A thick aluminum alloy extrusion shows the surface lifted and flaking away in layers, like the leaves of a book. What form of corrosion is this?

   • A.Stress corrosion cracking
   • B.Fretting corrosion
   • C.Filiform corrosion
   • D.Exfoliation corrosion✓ Answer

   Exfoliation is an advanced form of intergranular corrosion: attack follows grain boundaries running parallel to the surface, and the corrosion product occupies more volume than the metal it replaced, so it forces the layers apart. It is typical of extrusions and thin rolled sections whose grains are elongated in one direction, and any bulge or lifted skin at a lap joint should be suspected of it.

   Source: FAA-H-8083-30, Ch. 6 Cleaning and Corrosion Control, 'Intergranular and Exfoliation Corrosion'Report a problem with this question

10. 10. Wormlike traces of corrosion found under an intact paint film on an aluminum skin, typically traced to improper surface preparation and storage in high relative humidity, are known as what?

    • A.Filiform corrosion✓ Answer
    • B.Pitting corrosion
    • C.Fretting corrosion
    • D.Intergranular corrosion

    Filiform corrosion is an oxygen concentration cell that grows under an organic coating: the advancing head of the filament is starved of oxygen and therefore anodic, so it keeps tunneling under the paint, and it thrives at roughly 65 to 85 percent relative humidity. Because the cell lives under the finish, painting over it does nothing — the coating must be stripped, the corrosion removed, and the surface re-treated and refinished.

    Source: FAA-H-8083-30, Ch. 6 Cleaning and Corrosion Control, 'Filiform Corrosion'Report a problem with this question

11. 11. An aluminum alloy bracket is bolted directly against a graphite/epoxy composite panel and the joint gets wet. Which member corrodes, and why?

    • A.Neither, because a composite is nonmetallic and cannot take part in a galvanic couple
    • B.Both equally, because the electrolyte attacks each surface at the same rate
    • C.The graphite fibers, because carbon is anodic to aluminum
    • D.The aluminum, because it is anodic (more active) to graphite in the galvanic series, so it becomes the corroding member and a sealant or nonmetallic barrier must separate the two✓ Answer

    In a dissimilar-metal (galvanic) couple the more active, anodic material is the one consumed, and graphite is strongly cathodic — it sits far from aluminum in the galvanic series, so the aluminum corrodes rapidly wherever an electrolyte bridges the two. The standard prevention is to break the couple with primer, sealant, or nonmetallic washers and shims rather than relying on paint alone.

    Source: FAA-H-8083-30, Ch. 6 Cleaning and Corrosion Control, 'Dissimilar Metal (Galvanic) Corrosion' and galvanic seriesReport a problem with this question

12. 12. What is the correct way to remove light surface corrosion from an Alclad aluminum skin?

    • A.Abrade it with a steel wire brush and leave the metal bare, since the cladding will re-form on its own
    • B.Scrub the area with steel wool until the metal is bright, then wax it
    • C.Use aluminum wool, a nonmetallic abrasive mat, or an approved chemical treatment, blending only enough to remove the corrosion without cutting through the pure-aluminum cladding, then apply a conversion coating and refinish✓ Answer
    • D.Wash it with a strong alkaline household cleaner and rinse with water

    Steel wool and steel wire brushes embed steel particles in aluminum and start dissimilar-metal corrosion, and strong alkaline cleaners chemically attack aluminum, so neither is permitted. The Alclad layer is the corrosion barrier for the high-strength core beneath it, so blending must stay within the cladding, and protection is restored in the field with a chemical conversion coating (Alodine type, MIL-DTL-5541) followed by primer and topcoat — anodizing is a shop electrolytic process that cannot be re-created on the aircraft.

    Source: FAA-H-8083-30, Ch. 6 Cleaning and Corrosion Control, corrosion removal from aluminum/Alclad and chemical conversion coatingsReport a problem with this question

13. 13. In the aluminum designation 2024-T3, what do the leading digit '2' and the temper suffix 'T3' indicate?

    • A.Copper is the principal alloying element, and the metal was solution heat treated and then cold worked✓ Answer
    • B.Magnesium is the principal alloying element, and the metal was solution heat treated and artificially aged
    • C.Zinc is the principal alloying element, and the metal was strain hardened only
    • D.The metal is at least 99 percent pure aluminum, and it is in the annealed condition

    The first digit of the four-digit designation names the alloy family — 1xxx is 99 percent pure aluminum, 2xxx copper, 3xxx manganese, 5xxx magnesium, 6xxx magnesium and silicon, 7xxx zinc — and the temper suffix states the condition: -O annealed, -H strain hardened, -T3 solution heat treated then cold worked, -T4 solution heat treated and naturally aged, -T6 solution heat treated and artificially aged. Knowing both matters because 2xxx alloys are strong but less corrosion resistant, which is why 2024 sheet is normally supplied Alclad.

    Source: FAA-H-8083-30, Ch. 5 Aircraft Materials, aluminum alloy designation system and temper designationsReport a problem with this question

14. 14. Why must 2017 (D) and 2024 (DD) rivets be refrigerated after solution heat treatment, while 2117 (AD) rivets may be driven in the condition received?

    • A.Refrigeration anneals the rivet, and 2117 rivets are already annealed by the manufacturer
    • B.Refrigeration keeps the anodic film on D and DD rivets from drying out before driving
    • C.Refrigeration prevents corrosion of the bare alloy, and 2117 rivets are cadmium plated
    • D.Because 2017 and 2024 begin to precipitation (age) harden at room temperature soon after quenching, refrigeration retards the hardening so the rivets stay soft enough to drive; 2117 is heat treated by the manufacturer and retains its driving properties indefinitely✓ Answer

    Solution heat treatment followed by a rapid quench leaves 2017 and 2024 soft, but they age harden at room temperature within hours, so they are stored in a freezer ('icebox' rivets) to slow precipitation until they are driven — once they harden they must be re-heat-treated or they will crack when set. 2117 (AD) is supplied heat treated and stable, which is why it is the general-purpose structural rivet on most light aircraft.

    Source: FAA-H-8083-30, Ch. 5 Heat Treatment of aluminum alloy rivets and Ch. 7 rivet identificationReport a problem with this question

15. 15. A bolt is marked AN4-7A. What does that part number tell you?

    • A.A 4-inch overall length with a 7/8-inch grip and a drilled head
    • B.A 4/8-inch shank diameter, a 7/16-inch grip, and aluminum alloy construction
    • C.A shank diameter of 4/32 inch, a length of 7/16 inch, and an 'A' (aluminum) bolt
    • D.A shank diameter of 4/16 (1/4) inch, a grip length of 7/8 inch, and an undrilled shank with no cotter pin hole✓ Answer

    In the AN bolt system the first number is the shank diameter in sixteenths of an inch and the number after the dash is the grip length in eighths, while the letter A after the length means the shank is not drilled for a cotter pin. That last detail is a go/no-go item on installation: a castellated nut safetied with a cotter pin requires a drilled-shank bolt, so an 'A' bolt must be used with a self-locking or otherwise safetied nut.

    Source: FAA-H-8083-30, Ch. 7 Aircraft Hardware, AN bolt part numbering and head markingsReport a problem with this question

16. 16. Which application of a fiber-insert self-locking nut is prohibited?

    • A.On a bolt loaded in tension in a joint where nothing rotates
    • B.On an attach screw for an access panel in secondary structure
    • C.On a bolt or screw that rotates in service, such as a bolt used as a pulley or bellcrank pivot✓ Answer
    • D.In a location where the ambient temperature stays below 250 °F

    A fiber or nylon collar locks by friction against the bolt threads, and continuous rotation of the fastener wears that collar away, so self-locking nuts may not be used where the bolt or screw turns in operation. The same family of limits applies elsewhere: they are restricted to roughly 250 °F, are not used on fluid-carrying joints, and any nut that can be run down the threads by hand has lost its locking friction and must be discarded.

    Source: FAA-H-8083-30, Ch. 7 Aircraft Hardware, self-locking nuts; AC 43.13-1, Ch. 7 (nuts and their use)Report a problem with this question

17. 17. A nut must be tightened to 300 inch-pounds. A 2-inch extension is added in line with the handle of a torque wrench whose lever length is 10 inches. What torque must the wrench indicate?

    • A.250 inch-pounds✓ Answer
    • B.360 inch-pounds
    • C.240 inch-pounds
    • D.300 inch-pounds

    An extension used in line with the handle lengthens the effective lever arm, so the same hand force produces more torque at the nut than the wrench reads; the indicated value must be scaled down by indicated = desired × L ÷ (L + A) = 300 × 10 ÷ 12 = 250 inch-pounds. Using the uncorrected 300 reading would actually apply 360 inch-pounds to the fastener and overstretch it.

    Source: AC 43.13-1, Ch. 7 Sec. 2, torque wrench used with an extension/adapterReport a problem with this question

18. 18. Unless the maintenance manual says otherwise, published torque values for aircraft fasteners assume what thread condition, and what is the effect of lubricating the threads?

    • A.Lightly oiled threads; lubrication has no measurable effect on clamping force
    • B.Clean and dry threads; a lubricant lowers friction so the same indicated torque produces excessive preload and can overstretch or fail the bolt✓ Answer
    • C.Threads coated with anti-seize; a dry fastener would end up undertightened
    • D.Any condition, because a torque wrench measures clamping force directly

    A torque wrench measures the twisting effort needed to overcome thread and bearing friction, not the clamp-up load itself, so the published chart values are valid only for the clean, dry condition they were derived from. Oil or anti-seize can send a much larger share of that torque into stretching the bolt, and the resulting overload is invisible — which is why a wet value may be used only when the manufacturer publishes one.

    Source: AC 43.13-1, Ch. 7 Sec. 2, torque values based on clean and dry threads; FAA-H-8083-30, Ch. 7 torqueReport a problem with this question

19. 19. Which statement about safety wire installation is correct?

    • A.Wire that is removed may be straightened and installed again if it is free of corrosion and kinks
    • B.The wire may run in whichever direction is convenient as long as it is pulled taut and the pigtail is bent under
    • C.Each wire must be routed so that its pull on the fastener head is in the tightening direction, and safety wire is used only once and never reused✓ Answer
    • D.Single-strand wire is the normal method for widely spaced fasteners, and the double-twist method is reserved for close spacing

    Safety wire works only if any tendency of the fastener to back off puts the wire in tension in the tightening direction; wire routed the other way simply lets the bolt unscrew until the slack is taken up. Safety wire is also a single-use item, because installing and twisting work-hardens it and used wire can fail from vibration, and the double-twist method — not single-strand — is the standard practice for general applications.

    Source: AC 43.13-1, Ch. 7 Sec. 7, safety wiring (double-twist method, direction of pull, single use)Report a problem with this question

20. 20. A steel landing gear component is being inspected by the magnetic particle method. Which statement is correct?

    • A.Longitudinal magnetization is used to find lengthwise cracks and circular magnetization to find transverse cracks
    • B.Demagnetization is required only if the part will later be exposed to salt water
    • C.The method also works on aluminum and magnesium parts, because the particles are attracted to any metal surface
    • D.Circular magnetization reveals discontinuities running roughly parallel to the length of the part, longitudinal magnetization reveals those running across it, and the part must be demagnetized after inspection✓ Answer

    Magnetic particle inspection works only on ferromagnetic materials, and an indication forms where a flaw interrupts the magnetic field, which means a defect lying parallel to the field produces little or no leakage; that is why both circular and longitudinal magnetization are needed to cover both crack orientations. Demagnetization afterward is mandatory because residual magnetism attracts steel chips and can disturb compasses and other instruments installed near the part.

    Source: FAA-H-8083-30, nondestructive inspection — magnetic particle inspection (circular vs. longitudinal magnetization, demagnetization)Report a problem with this question

21. 21. A cast aluminum fitting is suspected of containing a flaw below the surface that does not break through to the outside. Which inspection method is appropriate?

    • A.Close visual inspection with a bright light and a magnifier
    • B.Ultrasonic inspection✓ Answer
    • C.Dye penetrant inspection
    • D.Magnetic particle inspection

    Ultrasonic inspection sends sound energy into the part and reads the reflection from an internal discontinuity, so it finds subsurface flaws in both ferrous and nonferrous material. Dye penetrant only reveals defects that are open to the surface, magnetic particle requires a ferromagnetic material and so cannot be used on aluminum, and visual inspection cannot see inside the casting at all; radiography is the other method capable of finding the internal flaw.

    Source: FAA-H-8083-30, nondestructive inspection — capabilities and limitations of penetrant, magnetic particle, eddy current, ultrasonic, and radiographic methodsReport a problem with this question

Practice questions based on 14 CFR Parts 43 and 65 and the FAA Aviation Maintenance Technician Handbook—General (FAA-H-8083-30). This site is not affiliated with or endorsed by the Federal Aviation Administration. This bank covers the GENERAL written test only; the Airframe and Powerplant written tests and the oral and practical exams are separate. Torque values, servicing quantities, corrosion rework limits, and inspection criteria always come from the manufacturer's current maintenance data and the applicable airworthiness directives — never from a practice test. Confirm current eligibility and testing requirements with the FAA before you test. About the A&P mechanic certificate →