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Storage of hydraulic power unit lines

Aviation Mechanic General (AMG) practice question 3 of 26 on Ground Operations and Servicing. ACS element AM.I.F.K14 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic General (AMG) practice mode.

Question bank updated 2026-09-22

QUESTIONWhen a portable hydraulic power unit is not in use, its lines are to be stored

  1. Awound on a reel and kept clean and dry.
  2. Bleft filled with fluid and capped at both ends.
  3. Ccoiled loosely on the floor beside the unit.
Show the answer and explanation

Correct answer: A. wound on a reel and kept clean and dry.

  • A — correct The handbook says the lines are to be stored, preferably wound on a reel, and kept clean, dry, and free of contaminants.
  • B — incorrect The handbook requires the lines to be kept dry and free of contaminants; it does not call for storing them filled.
  • C — incorrect Lines on the floor are exposed to contamination and kinks; the handbook prefers storage wound on a reel.

BACKGROUND

Hydraulic power units, sometimes called hydraulic mules, supply pressure to operate aircraft systems during maintenance and can deliver variable volume up to about 24 gallons per minute at pressures up to 3,000 psi. At such pressures a small stream from a leak can cut like a sharp knife, so the lines are inspected for cuts, frays, or other damage and kept free of kinks and twists. When not in use, the lines are stored, preferably wound on a reel, and kept clean, dry, and free of contaminants so that dirt is not introduced into the aircraft hydraulic system at the next connection.

STUDY TIP

Think of hydraulic lines as parts that must be protected from contamination between uses: reel, clean, dry.

KEY POINTS

  • Store hydraulic power unit lines wound on a reel.
  • Keep the lines clean, dry, and free of contaminants.
  • Inspect lines for cuts and frays; a 3,000 psi leak can cut like a knife.

SOURCES

  • FAA-H-8083-30B ch01 "Hydraulic Ground Power Units"
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MORE ON GROUND OPERATIONS AND SERVICING

SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-30B Aviation Maintenance Technician Handbook – General, 14 CFR part 43 and part 65. Regulations and handbooks are revised; confirm details against the current edition.