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Adding fluid to a shock strut

Aviation Mechanic Airframe (AMA) practice question 14 of 17 on Landing Gear Systems. ACS element AM.II.E.K2 · difficulty: applied. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONAll air has been released from a landing gear shock strut and the strut is fully compressed. What must be done before hydraulic fluid can be added?

  1. ADisconnect the torque links from the lower cylinder
  2. BRaise the aircraft until the strut is fully extended
  3. CUnscrew the air service valve from the strut
Show the answer and explanation

Correct answer: C. Unscrew the air service valve from the strut

  • A — incorrect Torque links keep the piston and wheels aligned and are not disturbed during a normal fluid fill.
  • B — incorrect The strut must be fully compressed for the fluid level check and fill; the fully extended position is used when bleeding the strut.
  • C — correct After the air is out and the strut is compressed, any valve core is removed and the entire service valve body is unscrewed from the strut so the strut can be filled to the level of the service valve port.

BACKGROUND

Checking a shock strut's fluid level requires most struts to be deflated and compressed to the fully compressed position. The servicing sequence is to remove the valve cap, check the swivel nut, depress a valve core to release trapped pressure, loosen the swivel nut to release all the air, and then compress the strut fully, using an exerciser jack if needed. Only then is the valve core of a core-type valve removed and the entire service valve body unscrewed from the strut. The strut is filled with the approved hydraulic fluid to the level of the service valve port, the valve is reinstalled with a new O-ring packing, and the strut is inflated slowly with air or nitrogen.

STUDY TIP

Memorize the servicing order as air out, strut compressed, valve out, fluid in, valve in, then inflate slowly; questions usually attack one step out of sequence.

KEY POINTS

  • The strut must be fully compressed and completely deflated first.
  • The service valve body is unscrewed so fluid can be added at the port.
  • Fluid is filled to the level of the service valve port with approved fluid.

SOURCES

  • FAA-H-8083-31B ch13 "Servicing Shock Struts"
Practice the Aviation Mechanic Airframe (AMA) test →Timed 100-question exam, by ACS area, or review your misses. Free.
MORE ON LANDING GEAR 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.