SkyDrill

Priority valve action at reduced system pressure

Aviation Mechanic Airframe (AMA) practice question 5 of 15 on Hydraulic and Pneumatic Systems. ACS element AM.II.F.K10 · difficulty: applied. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONA priority valve is set for 2,200 psi. If system pressure falls to 2,000 psi, what is the result?

  1. ANoncritical subsystems receive no pressure
  2. BAll subsystems continue to receive pressure
  3. CCritical subsystems are shut off first
Show the answer and explanation

Correct answer: A. Noncritical subsystems receive no pressure

  • A — correct When pressure drops below the valve setting, the priority valve closes and no fluid pressure flows to the noncritical systems.
  • B — incorrect All systems receive pressure only while pressure stays above the valve setting; below it the valve closes against the noncritical systems.
  • C — incorrect The purpose of the valve is the opposite: it gives the critical subsystems priority and cuts off the noncritical ones.

BACKGROUND

Pressure control valves keep fluid power systems operating safely and efficiently. A priority valve gives priority to the critical hydraulic subsystems over noncritical subsystems when system pressure is low. If the pressure setting of the priority valve is 2,200 psi, all systems receive pressure while the pressure is above 2,200 psi; if pressure drops below that setting, the priority valve closes and no fluid pressure flows to the noncritical systems. Some hydraulic designs accomplish the same result with pressure switches and electrical shutoff valves to assure that the critical systems have priority when system pressure is low.

STUDY TIP

Compare the priority valve with the pressure reducing valve: one decides who gets flow when supply is short, the other holds a lower steady pressure for a subsystem.

KEY POINTS

  • A priority valve protects critical subsystems when system pressure is low.
  • Above the valve setting, all subsystems receive pressure.
  • Below the setting, the valve closes and noncritical subsystems receive none.

SOURCES

  • sources/ama-airframe/ch12.txt "Priority Valves"
Practice the Aviation Mechanic Airframe (AMA) test →Timed 100-question exam, by ACS area, or review your misses. Free.
MORE ON HYDRAULIC AND PNEUMATIC 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.