18 Metallic Structures & Welding Practice Questions & Answers
Every Metallic Structures & Welding practice question from the FAA A&P Airframe (AMA) Practice Test, with the correct answer and a short explanation.
Start practice test →1. On a riveted sheet metal repair using universal head rivets, how is edge distance measured and what is the minimum permitted?
- A.Measured from the edge of the hole to the edge of the sheet, and not less than 2 rivet diameters
- B.Measured from the edge of the hole to the edge of the sheet, and not less than 3 rivet diameters
- C.Measured from the center of the hole to the edge of the sheet, and not less than 4 rivet diameters
- D.Measured from the center of the hole to the edge of the sheet, and not less than 2 rivet diameters✓ Answer
Edge distance is always measured from the center of the rivet hole to the nearest edge of the sheet. The minimum for protruding head rivets is 2 diameters, the maximum is 4 diameters, and about 2.5 diameters is preferred: closer than 2D lets the rivet tear out through the remaining land, while more than 4D allows the unsupported edge to curl up in flight.
Source: AC 43.13-1 Acceptable Methods, Techniques, and Practices, Ch. 4 (rivet edge distance)Report a problem with this question
2. In a multi-row riveted patch, what does transverse pitch describe and what is its usual value?
- A.The distance from hole center to sheet edge, normally 75 percent of the rivet pitch
- B.The distance between adjacent rivets in one row, normally 75 percent of edge distance
- C.The distance between rivet rows, normally about 75 percent of the rivet pitch✓ Answer
- D.The distance between rivet rows, normally about 150 percent of the rivet pitch
Rivet pitch is the spacing between rivet centers within the same row, while transverse pitch is the perpendicular spacing between the rows themselves. Transverse pitch is normally 75 percent of the rivet pitch and may never be less than 2.5 rivet diameters, which keeps the rows far enough apart that the material between them is not overloaded.
Source: FAA-H-8083-31 Aviation Maintenance Technician Handbook (Airframe), Ch. 4 (rivet layout)Report a problem with this question
3. A 0.032 inch skin is being riveted to a 0.040 inch doubler. Applying the standard rule of thumb, which rivet diameter should be selected?
- A.3/32 inch
- B.5/32 inch
- C.1/8 inch✓ Answer
- D.3/16 inch
Rivet diameter should be roughly three times the thickness of the thicker sheet being joined, then rounded up to the next standard size. Three times 0.040 inch is 0.120 inch, and the next standard rivet above that is 1/8 inch (0.125 inch); a smaller rivet would fail in shear before the sheet reached its bearing strength.
Source: FAA-H-8083-31 Aviation Maintenance Technician Handbook (Airframe), Ch. 4 (rivet selection)Report a problem with this question
4. What does the part number MS20470AD4-6 identify?
- A.A universal head 2117-T rivet 1/8 inch in diameter and 3/8 inch long✓ Answer
- B.A countersunk 2117-T rivet 1/8 inch in diameter and 3/8 inch long
- C.A universal head 2024-T rivet 3/8 inch in diameter and 1/8 inch long
- D.A universal head 2117-T rivet 4/16 inch in diameter and 6/8 inch long
In this coding 20470 is the universal (protruding) head and 20426 is the 100 degree countersunk head, AD designates 2117-T aluminum, the first dash number is the shank diameter in thirty-seconds and the second is the length in sixteenths. So 4 means 4/32 or 1/8 inch diameter and 6 means 6/16 or 3/8 inch length.
Source: AC 43.13-1 Acceptable Methods, Techniques, and Practices, Ch. 4 (rivet identification)Report a problem with this question
5. A solid rivet carries a raised cross on its manufactured head. Which alloy is it, and where is it used?
- A.2117-T aluminum, the general purpose rivet driven as received in most sheet repairs
- B.1100 aluminum, used only for non-structural items such as fairings and name plates
- C.5056 aluminum, used where the rivet is installed in or against magnesium structure✓ Answer
- D.2024-T aluminum, refrigerated before use and driven while still in the W condition
Head markings identify the rivet alloy: plain is 1100, a dimple is 2117-T, a raised dot is 2017-T, two raised dashes are 2024-T and a raised cross is 5056. The 5056 rivet is specified wherever the fastener contacts magnesium because the two metals are close enough in the electrochemical series to limit galvanic corrosion.
Source: AC 43.13-1 Acceptable Methods, Techniques, and Practices, Ch. 4 (rivet identification and head markings)Report a problem with this question
6. Which statement is true regarding 2024-T (DD) rivets?
- A.They must be annealed immediately before driving and then quenched after bucking
- B.They may be driven as received because the alloy is supplied in the annealed state
- C.They must be kept refrigerated and driven in the W condition soon after removal, before age hardening✓ Answer
- D.They must be artificially aged in an oven just before driving to reach full strength
2024-T rivets are too hard to drive as received, so they are solution heat treated and then stored below freezing to retard age hardening, which is why they are called icebox rivets. They must be driven in the soft unstable W condition shortly after removal from the refrigerator, whereas 2117-T and 7050 rivets need no heat treatment at all.
Source: FAA-H-8083-31 Aviation Maintenance Technician Handbook (Airframe), Ch. 4 (heat treatment of rivets)Report a problem with this question
7. Two sheets 0.032 inch and 0.040 inch thick are joined with 1/8 inch rivets. What total rivet length is required?
- A.0.13 inch
- B.0.26 inch✓ Answer
- C.0.32 inch
- D.0.20 inch
Total rivet length equals the grip length plus 1.5 times the shank diameter, the extra material needed to form the shop head. The grip here is 0.032 plus 0.040, or 0.072 inch, and 1.5 times 0.125 inch is 0.1875 inch, giving about 0.26 inch; too short a rivet starves the shop head and too long a one buckles the shank.
Source: FAA-H-8083-31 Aviation Maintenance Technician Handbook (Airframe), Ch. 4 (rivet length)Report a problem with this question
8. What are the dimensions of a correctly formed shop head on a solid rivet?
- A.About twice the shank diameter wide and equal to one shank diameter in height
- B.About one-half the shank diameter wide and one and one-half diameters in height
- C.About equal to the shank diameter in width and one-quarter of a diameter high
- D.About one and one-half times the shank diameter wide and one-half diameter high✓ Answer
A properly bucked shop head measures about 1.5 shank diameters across and 0.5 diameter high. The shop head, not the manufactured head, is the visual standard for a correct installation because those proportions show the shank has swelled enough to fill the hole and clamp the sheets without being overdriven.
Source: FAA-H-8083-31 Aviation Maintenance Technician Handbook (Airframe), Ch. 4 (rivet installation)Report a problem with this question
9. What is the purpose of the shielding gas in gas tungsten arc welding?
- A.It keeps atmospheric oxygen and nitrogen away from the puddle and hot electrode✓ Answer
- B.It raises the arc temperature by burning with the filler metal at the weld puddle
- C.It cools the weld zone rapidly so the base metal cannot harden as the joint cools
- D.It supplies the flux that forms a protective slag over the cooling weld bead
The inert gas blankets the molten pool and the hot tungsten electrode so atmospheric oxygen and nitrogen cannot reach them and form oxides, nitrides and porosity. Argon is heavier than air and blankets the puddle well, while helium gives a hotter, deeper penetrating arc and is often blended with argon.
Source: FAA-H-8083-31 Aviation Maintenance Technician Handbook (Airframe), Ch. 5 (inert gas welding)Report a problem with this question
10. A 90 degree bend is to be made in 0.040 inch sheet using an inside bend radius of 0.156 inch. What is the setback for this bend?
- A.0.116 inch
- B.0.176 inch
- C.0.196 inch✓ Answer
- D.0.392 inch
For a 90 degree bend, setback equals the inside bend radius plus the material thickness, so 0.156 plus 0.040 is 0.196 inch. The general form is SB equals K times the quantity R plus T, but K equals the tangent of half the bend angle and is therefore 1 at 90 degrees, so the K factor is only needed for bends other than 90 degrees.
Source: FAA-H-8083-31 Aviation Maintenance Technician Handbook (Airframe), Ch. 4 (layout and forming)Report a problem with this question
11. Using the formula BA = (0.01743R + 0.0078T) x N, what is the bend allowance for a 90 degree bend of 0.250 inch radius in material 0.051 inch thick?
- A.0.428 inch✓ Answer
- B.0.256 inch
- C.0.214 inch
- D.0.005 inch
Substituting gives 0.01743 times 0.250 equals 0.004358, plus 0.0078 times 0.051 equals 0.000398, for a sum of 0.004756 per degree, which multiplied by 90 degrees gives about 0.428 inch. Bend allowance is the length of material actually consumed in the bend, so it must be added between the flats when laying out the flat pattern.
Source: FAA-H-8083-31 Aviation Maintenance Technician Handbook (Airframe), Ch. 4 (bend allowance)Report a problem with this question
12. Which statement describes semimonocoque fuselage construction?
- A.The skin alone carries all flight loads and no internal longitudinal members are used
- B.The spars carry all bending loads and the skin serves only to shape the airfoil section
- C.Longerons, stringers, formers and bulkheads share the loads carried by the stressed skin✓ Answer
- D.A welded steel tube truss carries all loads and the skin carries none of the flight loads
True monocoque carries all loads in the shell alone, while semimonocoque adds longerons, stringers, formers and bulkheads that share the load with a stressed skin. Because the skin is a load carrying member in this construction, any dent, crack or corrosion in the skin is structural damage and a repair must restore the skin's original strength, not merely close the hole.
Source: FAA-H-8083-31 Aviation Maintenance Technician Handbook (Airframe), Ch. 1 (aircraft structures)Report a problem with this question
13. During inspection of a critically loaded stressed skin wing, which finding is evidence of actual structural damage?
- A.Chipped paint and light surface abrasion around scattered individual rivet heads
- B.Rivet heads tipped in random opposite directions at widely separated points
- C.Uniform staining running aft from one line of rivets across the wing skin
- D.Groups of consecutive rivet heads tipped in the same direction along a line, showing deflection✓ Answer
When several consecutive rivet heads are tipped the same way, the skin has deflected as a unit under a load beyond its design value, which is positive evidence of damage. The absence of visible rivet distortion does not prove the structure is sound, since bearing failure elongates the hole in the sheet rather than visibly tipping the rivet shank.
Source: FAA-H-8083-31 Aviation Maintenance Technician Handbook (Airframe), Ch. 4 (inspection of metal structures)Report a problem with this question
14. A damaged area of 2024-T3 Alclad skin is to be patched. What material should the repair use?
- A.Any alloy of the same thickness, since the rivets carry the load across the repair
- B.The same alloy and temper at the same thickness or heavier, or an approved equal of equal strength✓ Answer
- C.Non-structural 1100 aluminum of double thickness, because it forms and works easily
- D.A thinner sheet of a higher strength alloy, to keep the added repair weight down
A structural repair must restore the original strength without adding unnecessary weight, so the patch material must match the original alloy and temper and be at least as thick, or be a substitute of equal or greater strength approved by the manufacturer's repair data. Substituting a different alloy or a thinner gauge leaves the repaired area weaker than the structure it replaces.
Source: AC 43.13-1 Acceptable Methods, Techniques, and Practices, Ch. 4 (selection of repair material)Report a problem with this question
15. What is the maximum working pressure at which acetylene may be used for welding, and why?
- A.15 psi, because the regulator diaphragm will rupture if the setting goes higher
- B.15 psi, because free acetylene becomes unstable and may explode near 29.4 psi✓ Answer
- C.50 psi, because above that the cylinder's porous filler can no longer meter flow
- D.29.4 psi, because acetylene stays dissolved in the acetone below that pressure
Acetylene must never be used above 15 psi because free, undissolved acetylene becomes unstable and can detonate from a slight shock at about 29.4 psi. That is also why the cylinder is packed with a porous filler saturated with liquid acetone, in which the gas dissolves and remains stable at storage pressure.
Source: FAA-H-8083-31 Aviation Maintenance Technician Handbook (Airframe), Ch. 5 (welding gases and safety)Report a problem with this question
16. An acetylene cylinder has been transported lying on its side. What must be done before it is put into service?
- A.Reject the cylinder as unserviceable because the acetone is now contaminated
- B.Stand it upright for fifteen minutes and then bleed the acetone out of the valve
- C.Purge the regulator and hose for one minute and then use the cylinder as it stands
- D.Stand it upright for at least twice as long as it was lying down before using it✓ Answer
Acetylene cylinders are stored, transported and used upright because on their side the liquid acetone can migrate to the valve and be carried into the regulator, hose and torch. A cylinder that has lain down must stand upright at least twice as long as it was lying before use, so the acetone can settle back into the porous filler.
Source: FAA-H-8083-31 Aviation Maintenance Technician Handbook (Airframe), Ch. 5 (cylinder handling and storage)Report a problem with this question
17. Which oxyacetylene flame is used for hard facing and for welding nonferrous metals such as aluminum, nickel and Monel?
- A.A carburizing flame, with excess acetylene showing a feathery tip and burning cooler than neutral✓ Answer
- B.A slightly oxidizing flame, with excess oxygen and a shortened purplish inner cone
- C.A strongly oxidizing flame, with the inner cone cut to about one-tenth its normal length
- D.A neutral flame, with balanced oxygen and acetylene and a clearly defined inner cone
The carburizing or reducing flame has excess acetylene, shows a feathery plume on the inner cone and burns cooler than neutral, so it is used for hard facing, high carbon steels and nonferrous metals such as aluminum, nickel and Monel. A neutral flame is used for most steel welding because it does not alter the base metal chemistry, while an oxidizing flame is reserved for brass and bronze work.
Source: FAA-H-8083-31 Aviation Maintenance Technician Handbook (Airframe), Ch. 5 (oxyacetylene flame types)Report a problem with this question
18. A 4130 steel tube in a fuselage truss is dented. Within what limits may the dent be repaired by a welded patch?
- A.Not deeper than 1/10 of the tube diameter, not over 1/4 the circumference, not longer than the tube diameter✓ Answer
- B.Not deeper than 1/4 of the tube diameter, not over 1/2 the circumference, not longer than twice the diameter
- C.Not deeper than 1/10 of the wall thickness, not over 1/8 the circumference, not longer than half the diameter
- D.Not deeper than 1/2 of the tube diameter, not over 1/3 the circumference, not longer than three times the diameter
A welded patch repair is permitted when the dent is not deeper than one-tenth of the tube diameter, does not involve more than one-fourth of the circumference, is not longer than the tube diameter and is free of cracks, abrasions and sharp corners; the patch plate is the same material one gauge thicker. Filling a dent or crack with welding rod instead of reinforcing the member is never acceptable, because deposited rod adds no load path.
Source: AC 43.13-1 Acceptable Methods, Techniques, and Practices, Ch. 4 (repair of dented steel tubing)Report a problem with this question
Practice questions based on the Aviation Mechanic Airman Certification Standards (FAA-S-ACS-1), 14 CFR parts 43, 65, and 91, and the FAA Aviation Maintenance Technician Handbook—Airframe (FAA-H-8083-31). This site is not affiliated with or endorsed by the Federal Aviation Administration. This bank covers the AIRFRAME written test only; the General and Powerplant written tests and the oral and practical tests are separate. Torque values, cable tensions, inflation pressures, servicing quantities, wear limits, and repair criteria always come from the manufacturer's current maintenance data, the structural repair manual, 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 →