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Bonding an isolated exterior object

Aviation Mechanic Airframe (AMA) practice question 23 of 24 on Aircraft Electrical Systems. ACS element AM.II.K.K9 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONAn antenna element on the exterior of the airframe must remain electrically isolated from the structure. What must be provided for it?

  1. AA bond strap directly to structure, like every other exterior object
  2. BAn alternative means of conducting static and lightning currents
  3. CNo special provision, because it carries no current
Show the answer and explanation

Correct answer: B. An alternative means of conducting static and lightning currents

  • A — incorrect A direct bond strap would defeat the electrical isolation the antenna's function requires.
  • B — correct Objects whose function requires isolation are an exception to metallic surface bonding and must be given an alternative means to conduct static charges or lightning currents.
  • C — incorrect Leaving the object with no path at all is not permitted; static and lightning currents still have to be handled.

BACKGROUND

Inadequate bonding or grounding can lead to unreliable system operation, electromagnetic interference, electrostatic discharge damage to sensitive electronics, personnel shock hazard, or damage from a lightning strike. Metallic surface bonding requires that all conducting objects on the exterior of the airframe be electrically connected to the airframe through mechanical joints, conductive hinges, or bond straps capable of conducting static charges and lightning strikes. Exceptions may be necessary for objects such as antenna elements whose function requires them to be electrically isolated from the airframe. Such items should be provided with an alternative means to conduct static charges or lightning currents as appropriate. Static bonds also cover isolated conducting parts larger than 3 square inches and over 3 inches in linear dimension.

STUDY TIP

Treat isolation as an exception that still demands a current path; ask what happens to a lightning strike or static charge if the part has nowhere to send it.

KEY POINTS

  • Exterior conducting objects are normally bonded to the airframe.
  • Items that must stay isolated are an allowed exception.
  • Those items still need an alternative path for static and lightning currents.

SOURCES

  • sources/ama-airframe/ch09.txt "Bonding"
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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.