FAA Aviation Mechanic Airframe (AMA)Landing Gear SystemsMedium
A technician is servicing an oleo pneumatic shock strut that is low on both hydraulic fluid and air pressure. What is the correct servicing procedure?
- AAdd nitrogen first to full pressure, then top off fluid through the air valve
- BCompress the strut fully and add fluid without deflating the air charge
- CFully deflate the strut, extend it, add fluid to the correct level, then charge with nitrogen to the specified pressure/extension
- DAdd fluid and nitrogen simultaneously until the strut reaches full extension
Show answer & explanationAnswer & explanation
Correct answer: C. Fully deflate the strut, extend it, add fluid to the correct level, then charge with nitrogen to the specified pressure/extension
To properly service an oleo strut, all air pressure must first be released (strut fully deflated), the strut extended, hydraulic fluid added to the correct level per the manufacturer's chart, and then the strut recharged with nitrogen to the specified pressure and extension.
Why the other options are wrong
- A. Adding nitrogen before adjusting fluid level would trap incorrect fluid volume and give inaccurate final extension.
- B. Adding fluid without deflating traps residual air and produces inaccurate fluid quantity.
- D. Simultaneous servicing prevents accurate measurement of correct fluid level.
Oleo Strut Servicing
The process of properly filling an air-oil (oleo pneumatic) shock strut with hydraulic fluid and nitrogen to the manufacturer's specified levels.
- Strut must be deflated and extended before adding fluid
- Fluid level checked per manufacturer chart at specific extension
- Nitrogen charge added last to correct pressure/extension
Memory trick: Deflate, fill, then inflate—like changing a bike tire tube