FAA Aviation Mechanic Airframe (AMA)Hydraulic and Pneumatic SystemsHard
A technician needs to remove a hydraulic actuator for overhaul without draining the entire system reservoir or allowing excessive air to enter the lines. The hydraulic lines to the actuator are equipped with fittings that automatically seal both the line and the component port when separated. What type of fitting is being used?
- AA B-nut union fitting
- BA flareless tube fitting
- CAn AN flare fitting
- DA self-sealing quick-disconnect fitting
Show answer & explanationAnswer & explanation
Correct answer: D. A self-sealing quick-disconnect fitting
Self-sealing quick-disconnect fittings contain internal spring-loaded valves in both halves that automatically close when the fitting is separated, preventing significant fluid loss and minimizing air entry into the system. This allows components to be removed for maintenance without draining the entire hydraulic system.
Why the other options are wrong
- A. A B-nut union simply joins two tube ends with a standard flare connection and has no internal shut-off valve.
- B. A flareless tube fitting is a standard mechanical connection method but has no internal sealing valves that close automatically upon disconnection.
- C. An AN flare fitting is a standard threaded connection with no self-sealing feature; disconnecting it drains the line.
Self-Sealing Quick-Disconnect Fitting
A hydraulic line fitting containing internal check valves in both halves that automatically close when the fitting is disconnected, minimizing fluid loss and air entry during component removal.
- Used where components are frequently removed for maintenance
- Both halves seal independently upon separation
- Reduces need to drain system or bleed excessive air after reconnection
Memory trick: Quick-disconnect = 'self-closing garden hose nozzle' — no drip when you pull it apart.