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Pneumatic drill motors near flammable materials

Aviation Mechanic Airframe (AMA) practice question 18 of 20 on Metallic Structures. ACS element AM.II.A.K8 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONWhy are pneumatic drill motors recommended for repairs made around flammable materials?

  1. APneumatic motors cannot elongate a hole
  2. BElectric motors can produce sparks
  3. CElectric motors turn far too slowly there
Show the answer and explanation

Correct answer: B. Electric motors can produce sparks

  • A — incorrect Hole elongation comes from tilting the drill or using a bent bit, and can happen with either power source.
  • B — correct The handbook recommends pneumatic drill motors near flammable materials because potential sparks from an electric drill motor might become a fire hazard.
  • C — incorrect The recommendation is based on ignition risk, not on the speed at which either type of motor turns.

BACKGROUND

Portable power drills operate either by electricity or by compressed air, and the choice between them is partly a safety decision. Pneumatic drill motors are recommended for repairs around flammable materials, because potential sparks from an electric drill motor might become a fire hazard. Beyond the choice of motor, the handbook sets out basic precautions for any drilling: hold the drill firmly with both hands, place a backup block of wood under the hole to support the metal structure, and check the bit for trueness by running the motor freely before use. A bit that wobbles or is slightly bent should not be used, because it enlarges the hole. Safety goggles are to be worn at all times while drilling, and burrs formed around the hole must be removed so fasteners seat snugly and the surface is not scratched.

STUDY TIP

When a question offers a choice of tools, ask what hazard is present in that location. Fire risk is what pushes the selection toward air-powered tools.

KEY POINTS

  • Pneumatic drill motors are preferred near flammable materials because electric motors can spark.
  • Hold the drill with both hands and back up the work with a wood block.
  • Never use a bit that wobbles or is bent, as it enlarges the hole.

SOURCES

  • 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.