Free A&P Sheet Metal Structural Repair Questions and Answers — Questions and Answers
Question 1: During a visual inspection of a fuselage, a technician notices fine black streaks trailing back from several rivet heads. This phenomenon, commonly referred to as 'smoking,' is a primary indicator of which of the following conditions?
- Galvanic corrosion between the rivet and the skin material.
- Overheating of the rivet during installation.
- Fretting corrosion caused by slight movement of a loose rivet. (Correct answer)
- Improper application of primer around the rivet head.
Correct answer: Fretting corrosion caused by slight movement of a loose rivet.
The term 'smoking rivets' describes the fine black powder (aluminum oxide) that is worked out from under the rivet head due to slight, repeated movement under load or vibration. This movement is a form of fretting, which causes microscopic wear on the rivet and the surrounding skin, indicating the rivet is loose and its clamping force is compromised.
Question 2: A maintenance technician discovers a small crack propagating from a rivet hole in an aluminum alloy skin panel. According to standard repair practices, what is the immediate and primary action to be taken to prevent further propagation before a permanent repair is made?
- Weld the crack closed using an approved procedure.
- Replace the entire skin panel immediately.
- Apply a doubler patch over the entire area.
- Stop-drill the end of the crack. (Correct answer)
Correct answer: Stop-drill the end of the crack.
Stop-drilling is the correct immediate action to halt the growth of a crack. By drilling a small hole at the very tip of the crack, the sharp stress concentration at the crack's end is redistributed around the larger radius of the hole, which effectively stops or significantly slows its propagation. This allows for a permanent repair, such as a patch, to be performed later.
Question 3: Which of the following solid shank rivets, known as an 'icebox' rivet, must be heat-treated and then stored at low temperatures until it is driven to prevent age hardening?
- 2117-T3 (AD)
- 2024-T4 (DD) (Correct answer)
- 5056-H32 (B)
- 1100-F (A)
Correct answer: 2024-T4 (DD)
Rivets made from 2024 aluminum alloy (identified by two raised dashes or the code 'DD') are solution-heat-treated to soften them for driving. They begin to age-harden rapidly at room temperature, so they must be stored in a freezer ('icebox') and driven within a short period after removal (typically 10-20 minutes) to remain malleable.
Question 4: An A&P technician is laying out a repair pattern on a piece of 2024-T3 aluminum alloy sheet. To avoid creating potential points of failure, which of the following is the most appropriate tool for marking cut lines that will remain on the finished part?
- A fine-tipped carbide scribe.
- A steel awl.
- A graphite pencil or a permanent marker. (Correct answer)
- A ballpoint pen.
Correct answer: A graphite pencil or a permanent marker.
Using a scribe, awl, or any tool that scratches the surface of heat-treated aluminum alloys is prohibited because the scratch creates a stress riser. A stress riser is a microscopic groove that concentrates stress, potentially leading to the formation of a crack under load. A soft graphite pencil or a felt-tipped marker should be used for layout lines as they do not damage the material's surface.
Question 5: In a sheet metal repair, what is the term for the distance between the centers of adjacent rivets in the same row?
- Edge Distance
- Rivet Pitch (Correct answer)
- Transverse Pitch
- Rivet Gauge
Correct answer: Rivet Pitch
Rivet pitch is defined as the distance measured along the centerline of a single row of rivets, between the centers of adjacent rivets. Transverse pitch (or rivet gauge) is the distance between rows of rivets, and edge distance is the distance from the center of a rivet to the edge of the sheet metal.
Question 6: When forming a piece of sheet metal to a specific angle, what is the primary purpose of calculating the bend allowance?
- To calculate the total developed length (flat pattern) of the material needed for the part. (Correct answer)
- To determine the minimum bend radius to prevent cracking.
- To find the amount of springback that will occur after the bend is made.
- To establish the proper setback for the bend tangent lines.
Correct answer: To calculate the total developed length (flat pattern) of the material needed for the part.
Bend allowance is the length of the material in the bend itself, measured along the neutral axis. This value must be calculated and added to the lengths of the flat portions (legs) to determine the total length of material required for the part before it is bent. This total length is known as the developed length or flat pattern.
Free A&P Sheet Metal Structural Repair Questions and Answers
During a visual inspection of a fuselage, a technician notices fine black streaks trailing back from several rivet heads.
This phenomenon, commonly referred to as 'smoking,' is a primary indicator of which of the following conditions?