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Producing a rivet hole of correct size

Aviation Mechanic Airframe (AMA) practice question 13 of 20 on Metallic Structures. ACS element AM.II.A.K3 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONWhat is the correct procedure for producing a rivet hole of the required size in sheet metal?

  1. ADrill oversize, then peen the hole smaller
  2. BDrill straight to the final size in one pass
  3. CDrill an undersized pilot hole, then ream
Show the answer and explanation

Correct answer: C. Drill an undersized pilot hole, then ream

  • A — incorrect Working a hole smaller by peening deforms the surrounding sheet; an enlarged or deformed hole is instead drilled or reamed for the next larger size rivet.
  • B — incorrect A single full-size pass is not the specified method, and drill sizes for standard rivets are published as a pilot size and a separate final size.
  • C — correct The handbook directs the mechanic to first drill a slightly undersized pilot hole and then ream it with a twist drill of the appropriate size to obtain the required dimension.

BACKGROUND

The fit between rivet and hole controls how much of the joint's designed strength is actually realized, so hole preparation is treated as a discipline of its own. Before drilling, every rivet location is center punched, with the mark large enough to keep the drill from wandering yet not so heavy that it dents the surrounding surface; a bucking bar placed behind the sheet helps prevent denting. To bring the hole to size, the mechanic drills a slightly undersized pilot hole first and then reams it with a twist drill of the appropriate size. The drill is held at 90 degrees to the work or to the curvature of the material throughout, since tilting it on entry or withdrawal can elongate the hole into an egg shape. Afterward, all burrs are removed with a metal countersink or a file and the chips are cleaned away.

STUDY TIP

Memorize the pilot and final drill sizes for the standard rivet diameters, and connect each step of hole preparation to the failure it prevents.

KEY POINTS

  • Drill a slightly undersized pilot hole, then ream to the final dimension.
  • Center punch every location first, backing thin sheet with a bucking bar.
  • Hold the drill at 90 degrees; tilting it elongates the hole.

SOURCES

  • sources/ama-airframe/ch04.txt "Drilling"
  • sources/ama-airframe/ch04.txt "Portable Power Drills"
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SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-31B Aviation Maintenance Technician Handbook – Airframe, and 14 CFR part 43. Regulations and handbooks are revised; confirm details against the current edition.