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Compass fluid refilling authority

Aviation Mechanic Airframe (AMA) practice question 11 of 20 on Aircraft Instrument Systems. ACS element AM.II.H.K1 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONDuring a magnetic compass inspection, what does FAA airframe guidance state about the liquid in the compass bowl?

  1. AAn airframe mechanic may top it off with kerosene.
  2. BAn airframe mechanic cannot refill the fluid.
  3. CFluid level is not an inspection item.
Show the answer and explanation

Correct answer: B. An airframe mechanic cannot refill the fluid.

  • A — incorrect Although the compass case is filled with a liquid similar to kerosene, refilling is not an airframe mechanic task; the handbook states the mechanic cannot refill it.
  • B — correct The inspection items for a magnetic compass state that the bowl should be filled with liquid that is free of bubbles and discoloration, and that airframe mechanics cannot refill the fluid of a whiskey compass.
  • C — incorrect The condition of the liquid is explicitly listed among the items usually included in a compass inspection, so it cannot be ignored.

BACKGROUND

The magnetic compass is a simple instrument that requires no setting and no source of power, but it is delicate and must be handled carefully during inspection. The FAA lists the usual inspection items: correct readings on the cardinal headings with recompensation if needed, free movement of the moving parts, correct suspension of the bowl on its antivibration device without touching the metal container, a bowl full of liquid that has no bubbles and no discoloration, and a scale that is readable and well lit. The liquid, which is similar to kerosene, damps vibration and oscillation of the float assembly and reduces friction on the pivot. A bellows expansion unit inside the case keeps the case full as the liquid expands and contracts with altitude and temperature. The handbook states plainly that airframe mechanics cannot refill the fluid of a whiskey compass, so a low or bubbled bowl is a reason to remove the instrument rather than service it on the aircraft.

STUDY TIP

Memorize the five magnetic compass inspection items as a list, and note which findings you may correct yourself and which require sending the instrument out.

KEY POINTS

  • Compass inspection covers readings, free movement, suspension, fluid condition, and scale legibility.
  • The bowl must be full of liquid with no bubbles and no discoloration.
  • An airframe mechanic is not authorized to refill the compass fluid.

SOURCES

  • sources/ama-airframe/ch10.txt "Magnetic Compass Maintenance & Compensation"
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MORE ON AIRCRAFT INSTRUMENT 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.