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Purpose of hydraulic quick disconnect valves

Aviation Mechanic Airframe (AMA) practice question 4 of 15 on Hydraulic and Pneumatic Systems. ACS element AM.II.F.K9 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONQuick disconnect valves are installed in the pressure and suction lines immediately upstream and downstream of the power pump in order to do what?

  1. Arelieve pressure surges in the pump case drain line
  2. Bprevent fluid loss when the pump is removed
  3. Cshut off flow when a downstream line bursts
Show the answer and explanation

Correct answer: B. prevent fluid loss when the pump is removed

  • A — incorrect Damping pressure surges is a function of the accumulator, and case drain protection is handled by filters and relief provisions, not by a quick disconnect.
  • B — correct Quick disconnect valves are installed in hydraulic lines to prevent loss of fluid when units are removed, and they are placed on each side of the power pump for that reason.
  • C — incorrect Detecting a sudden increase in flow from a burst line and shutting the flow off is the function of a hydraulic fuse.

BACKGROUND

Quick disconnect valves are installed in hydraulic lines to prevent loss of fluid when units are removed. They are installed in the pressure and suction lines of the system immediately upstream and downstream of the power pump. Besides permitting pump removal, these valves allow a power pump to be disconnected from the system so that a hydraulic test stand can be connected in its place. Each valve unit consists of two interconnecting sections coupled together by a nut when installed, and each section has a piston and poppet assembly that is spring loaded to the closed position when the unit is disconnected.

STUDY TIP

Keep the line-protection devices distinct: quick disconnects save fluid during component removal, while hydraulic fuses save fluid after a line failure.

KEY POINTS

  • Quick disconnect valves prevent fluid loss when units such as the power pump are removed.
  • They are fitted in the pressure and suction lines on each side of the power pump.
  • Each half is spring loaded closed when disconnected, and the pair also allows a test stand to be substituted for the pump.

SOURCES

  • sources/ama-airframe/ch12.txt "Quick Disconnect Valves"
  • sources/ama-airframe/ch12.txt "Hydraulic Fuses"
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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.