An oleo strut absorbs the landing impact shock with what?

• A. Air
• B. Oil
• C. Water
• D. Grease

Answer: (B)

When a wheel oleo strut is compressed during landing, the energy of the impact is damped primarily by the hydraulic oil inside the strut. As the piston moves, the oil is forced through restricted passages or metering orifices, converting the kinetic energy of the landing into heat and providing controlled deceleration. The gas above the oil acts as a spring, helping to push the strut back out after compression. This combination—oil for damping and gas for spring—defines the oleo-pneumatic shock absorber. Air would not provide the same controlled damping, water isn’t used in this role, and grease does not flow to provide proper damping. Therefore, oil is the damping medium.