2025 Airframe Mechanic Test Guide

Metallic Structures

8107. Which statement is true regarding the inspection of a stressed skin metal wing assembly known to have been critically loaded?

Answer: C. If genuine rivet tipping has occurred, groups of consecutive rivet heads will be tipped in the same direction.

Explanation: If the structure has actually been damaged, this would be indicated by groups of consecutive rivet heads being tipped in the same direction caused by a major deflection of the skin under load. (AM.II.A.K1) -- FAA-H-8083-31

8061. What precaution, if any, should be taken to prevent corrosion inside a repaired metal honeycomb structure?

Answer: A. Prime the repair with a corrosion inhibitor and seal from the atmosphere.

Explanation: When a repair to a metal honeycomb structure is made, the repair should be primed with a corrosion-inhibiting primer and should be sealed so no moisture or air can get to the inside of the repair. (AM.II.A.K3) -- FAA-H-8083-31

8114. When repairing a small hole on a metal stressed skin, the major consideration in the design of the patch should be

Answer: A. the shear strength of the riveted joint.

Explanation: When repairing a small hole in a metal stressed skin, the rivets should take all the stress from the skin and carry it into the patch. On the opposite side of the damage, this stress is carried back into the skin. The shear strength of the riveted joints should be slightly less than the bearing strength of the skin. If a failure should occur, it will be a shear failure of the rivets, rather than a bearing failure of the skin. (AM.II.A.K3) -- FAA-H-8083-31

8116. Repairs or splices involving stringers on the lower surface of stressed skin metal wings are usually

Answer: C. permitted but are normally more critical in reference to strength in tension than similar repairs to the upper surface.

Explanation: Repairs or splices to the stringers on the lower surface of a stressed skin metal wing are permitted, but since the lower surface of the wing is under a tensile load in flight, these repairs are more critical with regard to tensile strength than repairs to the upper surface. (AM.II.A.K3) -- AC 43.13-1B

8118. Clad aluminum alloys are used in aircraft because they

Answer: B. have surface layers of pure aluminum or aluminum alloy bonded to the core material to inhibit corrosion.

Explanation: Clad aluminum alloys are used in aircraft construction because they are less subject to corrosion than uncoated aluminum alloys. Pure aluminum which is not susceptible to corrosion is used to coat a sheet of high-strength aluminum alloy to protect it from corrosion. (AM.II.A.K3) -- FAA-H-8083-31

8120. Aircraft structural units, such as spars, engine supports, etc., which have been built up from sheet metal, are normally

Answer: A. repairable, using approved methods.

8123. Parts fabricated from Alclad 2024-T3 aluminum sheet stock must have all

Answer: C. scratches, kinks, tool marks, nicks, etc., held to a minimum.

Explanation: When fabricating parts from Alclad 2024-T3 aluminum sheet stock, be sure that all damage such as scratches, kinks, tool marks, and nicks are held to a minimum to prevent exposing the alloy core through the damaged pure aluminum surface coating. (AM.II.A.K3) -- FAA-H-8083-31

8161. If a streamline cover plate is to be hand formed using a form block, a piece of dead soft aluminum should first be placed over the hollow portion of the mold and securely fastened in place. The bumping operation should be

Answer: B. started by tapping the aluminum lightly around the edges and gradually working down into the center.

Explanation: When using the bumping operation to form a compound curve in a piece of soft aluminum, use light blows of the mallet to work the material down gradually from the edges. Always start bumping near the edge of the form. Never start in the center. (AM.II.A.K3) -- FAA-H-8083-31

8170. You can distinguish between aluminum and aluminum alloy by

Answer: C. testing with a 10 percent solution of caustic soda.

Explanation: Aluminum alloys of the 2XXX series can be identified by using a 10 percent solution of caustic soda. When this solution is applied to the material, it reacts with the copper in the alloy and forms a dark spot. (AM.II.A.K3) -- FAA-H-8083-31

8058. When repairing puncture-type damage to a metal-faced laminated honeycomb panel, the edges of the doubler should be tapered to

Answer: B. 100 times the thickness of the metal.

Explanation: When repairing puncture-type damage to a metal-faced laminated honeycomb panel, cut a piece of aluminum alloy the same thickness or thicker than the original face. Taper the edges of this patch back to a ratio of about 100 to one. (AM.II.A.K4) -- FAA-H-8083-31

8112. Which is correct concerning the use of a file?

Answer: A. Apply pressure on the forward stroke, only, except when filing very soft metals such as lead or aluminum.

Explanation: To prevent undue wear on the file, when filing any metal other than lead or soft aluminum, apply pressure only during the forward stroke. Relieve the pressure during the return stroke. (AM.II.A.K4) -- FAA-H-8083-31

8115. Which procedure is correct when using a reamer to finish a drilled hole to the correct size?

Answer: B. Turn the reamer only in the cutting direction.

Explanation: When using a reamer to enlarge a hole, always turn the reamer in the direction of cutting. If the direction of reamer motion is reversed, the reamer will be seriously dulled. (AM.II.A.K4) -- FAA-H-8083-31

8117. When straightening members made of 2024-T4, you should

Answer: A. straighten cold and reinforce.

Explanation: If a structural member made of 2024-T4 aluminum alloy is bent, it should be straightened cold and then reinforced. (AM.II.A.K4) -- FAA-H-8083-31

8138. The primary alloying agent of 2024-T3 is indicated by the number

Answer: A. 2.

Explanation: The primary alloying agent in 2024-T36 aluminum alloy is copper, which is identified by the first digit 2. (AM.II.A.K4) -- FAA-H-8083-31

8139. Which part of the 2017-T36 aluminum alloy designation indicates the primary alloying agent used in its manufacture?

Answer: A. 2.

Explanation: The primary alloying agent in 2017-T36 aluminum alloy is copper which is identified by the digit 2. (AM.II.A.K4) -- FAA-H-8083-31

8175. The sight line on a sheet metal flat layout to be bent in a cornice or box brake is measured and marked

Answer: C. one radius from the bend tangent line that is placed under the brake.

Explanation: When making a bend in a piece of sheet metal in a cornice or box brake, draw a sight line inside the bend allowance that is one bend radius from the bend tangent line that is placed under the brake. Sight down vertically over the edge of the radius bar and place this sight line directly in line with the edge of the radius bar. In this position the bend tangent line is at the beginning of the radius. (AM.II.A.K4) -- FAA-H-8083-31

8042. A main difference between Lockbolt/Huckbolt tension and shear fasteners (other than their application) is in the

Answer: A. number of locking collar grooves.

Explanation: A lockbolt has locking grooves in its pin into which the collar is swaged. A shear lockbolt has two locking grooves, and the tension lockbolt has five grooves. (AM.II.A.K5) -- FAA-H-8083-31

8044. The general rule for finding the proper rivet diameter is

Answer: C. three times the thickness of the thickest sheet.

Explanation: A rule of thumb for determining the rivet diameter to be used for repairing aircraft sheet metal is to use a rivet whose diameter is approximately three times the thickness of the thickest sheet being joined. (AM.II.A.K5) -- FAA-H-8083-31

8045. The shop head of a rivet should be

Answer: A. one and one-half times the diameter of the rivet shank.

Explanation: The shop, or bucked, head of a rivet should have a diameter of 1-1/2 times the rivet shank diameter and a thickness of 1/2 of the shank diameter. (AM.II.A.K5) -- FAA-H-8083-31

8046. One of the main advantages of HI-LOK type fasteners over earlier generations is that

Answer: C. they can be installed with ordinary hand tools.

Explanation: HI-LOK fasteners are a new form of Hi-Shear fastener that can be installed with ordinary hand tools rather than requiring the special riveting tools. The pin is installed in an interference-fit hole and the collar screwed down over the threaded end. The pin is held with an Allen wrench and the collar is screwed down, using an open-end wrench until the proper torque is reached. At this point, the hex shear-nut portion of the collar will break off. (AM.II.A.K5) -- FAA-H-8083-31

8046-1. Which of the following is one advantage of HI-LOK fasteners?

Answer: C. Inability to be over-torqued.

Explanation: The advantages of a HI-LOK two-piece fastener include its light weight, high fatigue resistance, high strength, and its inability to be over-torqued. (AM.II.A.K5) -- FAA-H-8083-31

8047. The markings on the head of a Dzus fastener identify the

Answer: A. body diameter, type of head, and length of the fastener.

Explanation: Dzus fasteners are identified by marks on the head of the stud. A letter identifies the type of head, a number identifies the body diameter in 1/16-inch increments, and another number identifies the stud length in hundredths of an inch. (AM.II.A.K5) -- FAA-H-8083-31

8048. The Dzus turnlock fastener consists of a stud, grommet, and receptacle. The stud length is measured in

Answer: A. hundredths of an inch.

Explanation: The stud length of a Dzus fastener is measured in 1/100-inch increments. (AM.II.A.K5) -- FAA-H-8083-31

8049. The Dzus turnlock fastener consists of a stud, grommet, and receptacle. The stud diameter is measured in

Answer: C. sixteenths of an inch.

Explanation: The diameter of the stud of a Dzus fastener is measured in 1/16-inch increments. (AM.II.A.K5) -- FAA-H-8083-31

8050. Threaded rivets (Rivnuts) are commonly used to

Answer: B. attach parts or components with screws to sheet metal.

Explanation: Rivnuts are a special type of blind rivet whose shank has internal threads. When the Rivnut is upset in a piece of thin sheet metal, the threaded shank acts as a nut to receive a machine screw. Rivnuts were originally designed to attach deicer boots to thin sheet metal wing and empennage leading edges. (AM.II.A.K5) -- FAA-H-8083-31

8100. Select the alternative which best describes the function of the flute section of a twist drill.

Answer: C. Forms the cutting edges of the drill point.

Explanation: One of the functions of the flutes cut into the shank of a twist drill is to form the cutting edges of the drill point. (AM.II.A.K5) -- FAA-H-8083-31

8101. How many MS20470 AD-4-6 rivets will be required to attach a 10" x 5" plate, using a single row of rivets, minimum edge distance, and 4D spacing?

Answer: A. 56.

Explanation: The plate is 10 inches long and 5 inches wide. The rivets have a diameter of 1/8 inch and there is an edge distance of two rivet diameters. This requires two rows of rivets 9-1/2 inches long and two rows that are 4-1/2 inches long. The total length of the rivet seams is 28 inches. If the rivets are spaced every 1/2 inch (4D spacing), 56 rivets are needed. (AM.II.A.K5) -- AC 43.13-1B

8104. What should be the included angle of a twist drill for soft metals?

Answer: B. 90°.

Explanation: For drilling soft metals, an included angle of about 90° (45° either side of center) is suitable. For normal metals, an angle of 118° (59° on either side of center) is considered the standard lip angle. (AM.II.A.K5) -- FAA-H-8083-31

8105. When comparing the machining techniques for stainless steel sheet material to those for aluminum alloy sheet, it is normally considered good practice to drill the stainless steel at a

Answer: B. lower speed with more pressure applied to the drill.

Explanation: When drilling stainless steel, you should use a drill with a larger included angle. Use a lower speed and more pressure than you would use for aluminum alloy. (AM.II.A.K5) -- FAA-H-8083-31

Non-Metallic Structures

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Flight Controls

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Airframe Inspection

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Landing Gear Systems

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Hydraulic and Pneumatic Systems

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Environmental Systems

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Aircraft Instrument Systems

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Communication and Navigation Systems

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Aircraft Fuel Systems

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Aircraft Electrical Systems

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Ice and Rain Control Systems

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Airframe Fire Protection Systems

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Rotorcraft Fundamentals

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Water and Waste Systems

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The Oral and Practical Tests

Applicants must pass written, oral, and practical tests. O&P tests are typically administered by an FAA Designated Mechanic Examiner (DME). Applicants need to bring specific documentation, including FAA Forms 8610-2, written test results, and photo identification. Eligibility can be based on graduation from an FAA-certificated 14 CFR Part 147 AMTS, civil/military practical experience, or progress at an AMTS.

Oral-related Questions: The oral test has three sections: General, Airframe, and Powerplant. The number of questions varies based on written test performance. A minimum of 4 questions per section is required. A 70% passing standard applies to the entire oral test, not by subject area. Missed ACS codes on the written test may result in additional oral questions.

Practical-related Questions: There are practical tests for General, Airframe, and Powerplant, each with a set number of projects. Projects are graded pass/fail. A 70% passing standard applies to the entire practical test. If an applicant answers practical questions correctly but fails to complete a project satisfactorily, the project is failed.

Sample Oral Exam:

• Question: What are the four common basic stresses on an aircraft? Answer: Tension, compression, shear, and bearing. (Ref: FAA-H-8083-31A)
• Question: Name one aircraft structure that a honeycomb panel can be used for. Answer: Floor panels, bulkheads, control surfaces, wing skin panels. (Ref: FAA-H-8083-31A)
• Question: In relation to an aircraft, what is the boundary layer? Answer: The part of the airflow closest to the surface of the aircraft. (Ref: FAA-H-8083-31A)
• Question: To establish conformity of an aircraft product the mechanic must start with what document? Answer: The Type Certificate Data Sheet. (Ref: FAA-H-8083-31)
• Question: References to auxiliary landing gear refer to what gear on any particular aircraft? Answer: Nose gear, tail gear, or outrigger-type. (Ref: FAA-H-8083-31)
• Question: Hydraulic system liquids are used primarily for what? Answer: To transmit and distribute forces to various units to be actuated. (Ref: FAA-H-8083-31)
• Question: The production of gaseous oxygen for commercial or aircraft cylinders is often through what process? Answer: Liquefying air. (Ref: FAA-H-8083-31)
• Question: There are usually two parts to any instrument or instrument system. What are they? Answer: One part senses the situation and the other part displays it. (Ref: FAA-H-8083-31)
• Question: What is the actuating (output) element component of an autopilot system? Answer: The servo. (Ref: FAA-H-8083-31)
• Question: What does the first number in a fuel performance number indicate? Answer: It indicates the octane rating of the fuel in a lean air-fuel mixture. (Ref: FAA-H-8083-31)
• Question: What is battery capacity measured in? Answer: Measured in amp-hours. (Ref: FAA-H-8083-31A)
• Question: Name one of the most common anti-icing systems in use. Answer: Thermal pneumatic, thermal electric, and chemical. (Ref: FAA-H-8083-31)
• Question: What are the two most common types of portable fire extinguishers used in cabins or flight decks? Answer: Halon 1211 and water. (Ref: FAA-H-8083-31)
• Question: What are the two main parts of a rotorcraft swash plate? Answer: The stationary swash plate and the rotating swash plate. (Ref: FAA-H-8083-31)
• Question: What are the components used to heat water supply lines and waste water tanks? Answer: Heater blankets and in-line heaters. (Ref: FAA-H-8083-31)

Sample Practical Exam:

Project: Airframe Inspection

Description: Provide a checklist for conducting a 100-hour inspection.

Given: Assigned aircraft, appropriate reference material.

Performance Standard: The applicant will provide a checklist for conducting a 100-hour inspection on the assigned aircraft.

ACS Code: AM.II.D.S5 Reference: 14 CFR Part 43

Question: What is the first step in conducting a 100-hour inspection? Answer: The first step is to clean the aircraft. (Ref: 14 CFR Part 43)

ACS Code: AM.II.D.R4

Question: Who is required to maintain the records of inspection? Answer: The owner/operator is required to retain records of inspection. (Ref: 14 CFR Part 43)

ACS Code: AM.II.D.K2

Metallic Structures (Typical Oral Questions)

1. Requirements for Sheet Metal Repair: Restore lost strength and rigidity, do not change aerodynamic shape.

2. Rivet vs. Sheet Strength: Bearing strength of the sheet should be greater than rivet shear strength.

3. Cleco Fastener: A patented fastener used to hold sheet metal pieces together until riveting.

4. Throatless Shears Function: Cutting mild carbon steel and stainless steel, including irregular curves.

5. Sight Line Purpose: Positions cornice brake jaws for accurate bends starting at the bend tangent line.

6. Slip Roll Former: Used for simple curves with large radii.

7. Bumping: Used for compound curves in sheet metal.

8. Flange Curving: Stretch for convex curves, shrink for concave curves.

9. Bend Allowance: Amount of metal used in making a bend.

10. Minimum Bend Radius: Determined by material thickness and hardness.

11. Setback: Distance jaws of a brake are set back from the mold line to form a bend.

12. Lightening Hole Flanges: Provide rigidity to the rib.

13. Concave Curve Forming: Start at the edges and work toward the center.

14. Joggle: A small offset allowing sheets to overlap.

15. Drilling Stainless Steel: Turn drill slowly.

16. Minimum Edge Distance for Rivets: Two times the diameter of the rivet.

17. Transverse Pitch for Two-Row Splice: Three-fourths of the pitch of the rivets in the rows.

18. Aluminum Alloy Rivet Driving: Use as few blows as practical to avoid work-hardening.

19. Dimpling vs. Countersinking: Depends on sheet thickness; countersinking for thicker sheets.

20. Hot-Dimpling Metals: 7075-T6, 2024-T81 aluminum alloys, and magnesium alloys.

21. Anodizing Purpose: Creates a protective oxide film on aluminum alloy via an electrolytic process.

22. TIG vs. Oxyacetylene Welding: TIG is preferred for steel tube structures due to concentrated heat and less distortion.

23. Acetylene Cylinder Pressure: Must be kept low (below 15 psi) as gas becomes unstable at higher pressures.

24. Oxy-Acetylene Flame Types: Oxidizing (pointed inner cone, hissing), Neutral (rounded inner cone, no feather), Reducing (definite feather).

25. Tack Welding: Small welded spots to hold material before final bead.

26. Thick Plate Preheating: Controls expansion/contraction and minimizes stresses during welding.

27. Welding Flux Removal: Essential because flux is corrosive and can cause metal corrosion.

28. Inert Gas Function (TIG/MIG): Forms a shield to protect the weld puddle from oxygen, preventing oxide formation.

29. Brazing vs. Welding: Brazing joins metals with a filler alloy without melting base metal; welding melts base metal.

30. Heat-Treated Steel Repair: Not normally repairable by welding as it destroys the heat treatment.

31. Solder for Electrical Wires: 60/40 resin-core solder recommended.

32. Gas Welding Aluminum Flame: A soft, neutral oxy-hydrogen flame is recommended.

33. Acetylene Line Pressure: Acceptable pressure is about 5 psi.

34. Butt Weld Penetration: The joint should have 100 percent penetration.

35. Soft Flame: Made with low gas pressures, resulting in no noise and no puddle blow.

Typical Practical Projects:

1. Lay out and form a channel from aluminum alloy sheet using minimum bend radius.
2. Install special rivets to join two pieces of aluminum alloy sheet.
3. Perform a flush patch repair on a sheet metal aircraft structure.
4. Demonstrate proper drilling technique for stainless steel.
5. Identify aircraft rivets by part number and material.
6. Demonstrate correct setup and use of a squeeze riveter.
7. Properly remove rivets from aircraft structure.
8. Demonstrate correct setup and use of an oxy-acetylene cutting torch, including cutting steel.