FAA Aviation Mechanic Airframe (AMA)Landing Gear SystemsMedium
A technician is inspecting a hydraulic parking brake system that uses a component to store pressurized fluid so the parking brakes remain applied even after the aircraft's engine-driven hydraulic pump is shut down. Which component performs this function?
- ARelief valve
- BHydraulic accumulator
- CSelector valve
- DCheck valve
Show answer & explanationAnswer & explanation
Correct answer: B. Hydraulic accumulator
A hydraulic accumulator stores pressurized fluid using a compressed gas charge against a diaphragm or piston, allowing the parking brakes to remain applied over time even after the hydraulic pump is no longer running, compensating for minor internal leakage.
Why the other options are wrong
- A. A relief valve limits maximum system pressure but does not store pressure for later use.
- C. A selector valve directs flow to different systems but has no pressure storage capability.
- D. A check valve allows one-way flow but does not store pressurized fluid itself.
Hydraulic Accumulator (Parking Brake)
A pressure-storage device using a gas charge to maintain hydraulic pressure on the parking brakes after the pump is shut down, compensating for minor fluid leakage.
- Uses compressed gas (often nitrogen) against a piston or diaphragm
- Maintains brake pressure with pump off
- Common in parking brake circuits to hold brakes over time
Memory trick: 'Accumulator is the battery of hydraulic pressure, holding the brake charge'