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Recommended shielding coverage

Aviation Mechanic Airframe (AMA) practice question 22 of 24 on Aircraft Electrical Systems. ACS element AM.II.K.K8 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONWhat minimum shielding coverage is recommended for aircraft wire shielding?

  1. A50 percent or greater
  2. B100 percent, with no gaps permitted
  3. C85 percent or greater
Show the answer and explanation

Correct answer: C. 85 percent or greater

  • A — incorrect Half coverage is well below the recommended amount and would leave the circuit open to interference.
  • B — incorrect Complete coverage is not the stated requirement; 85 percent or greater is what is recommended.
  • C — correct Use of shielding with 85 percent coverage or greater is the recommended figure.

BACKGROUND

Modern aircraft carry many highly sensitive electronic devices, so proper shielding of electrical circuits has become very important. Shielding is the process of applying a metallic covering to wiring and equipment to eliminate electromagnetic interference, which occurs when electromagnetic fields induce high-frequency voltages in a wire or component. Those induced voltages can cause system inaccuracies or even failure. Use of shielding with 85 percent coverage or greater is recommended, and coaxial, triaxial, twinaxial, or quadraxial cables should be used where appropriate with their shields grounded at a single point or at multiple points depending on the purpose of the shielding. The grounded airframe structure may also be used as an EMI shield.

STUDY TIP

Hold on to the 85 percent figure, and connect shielding in your mind with EMI and crosstalk rather than with mechanical protection.

KEY POINTS

  • Shielding is a metallic covering applied to eliminate EMI.
  • Coverage of 85 percent or greater is recommended.
  • Shields are grounded at a single point or multiple points as required.

SOURCES

  • sources/ama-airframe/ch09.txt "Wire Shielding"
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MORE ON AIRCRAFT ELECTRICAL SYSTEMS

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.