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Bond and ground connection resistance

Aviation Mechanic Airframe (AMA) practice question 19 of 24 on Aircraft Electrical Systems. ACS element AM.II.K.K15 · 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 is the maximum resistance normally allowed for a bond or ground connection?

  1. A0.3 ohm
  2. B0.03 ohm, measured after refinishing
  3. C0.003 ohm
Show the answer and explanation

Correct answer: C. 0.003 ohm

  • A — incorrect This is a hundred times the allowed value and would indicate a poor connection.
  • B — incorrect The value is ten times too high, and bonds are tested after connections are made but before refinishing.
  • C — correct The resistance of each bond or ground connection should normally not exceed 0.003 ohm.

BACKGROUND

The resistance of all bond and ground connections should be tested after the connections are made and before refinishing. The resistance of each connection should normally not exceed 0.003 ohm, and a high quality test instrument such as an AN/USM-21A or equivalent is required to measure such very low values accurately. Bonding jumpers should be made as short as practicable and installed so that the resistance of each connection does not exceed 0.003 ohm. To ensure a low-resistance connection, nonconducting finishes such as paint and anodizing films must be removed from the attachment surface contacted by the bonding terminal. Corrosion is one of the more frequent causes of bonding and grounding failures, so completed connections should be post-finished quickly with a suitable coating.

STUDY TIP

Commit the figure 0.003 ohm to memory and note that an ordinary multimeter cannot resolve it, which is why a special low-resistance tester is called for.

KEY POINTS

  • Bond and ground connections are tested before refinishing.
  • Each connection should normally not exceed 0.003 ohm.
  • A high quality low-resistance test instrument is required.

SOURCES

  • sources/ama-airframe/ch09.txt "Testing of Bonds & Grounds"
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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.