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Upskill / Aircraft Maintenance / Hydraulic systems: power, pressure and protection

Hydraulic systems: power, pressure and protection

How aircraft hydraulic systems make, store, clean and protect pressure, how they are certified and serviced, and how to find faults and decide on dispatch

By Aerospace Garage Desk · Basics · 45 minutes · 24 narrated pages

  1. Part 1 · Basics

    Hydraulic systems: power, pressure and protectionYou are here

  2. Part 2 · In practice

    Troubleshooting hydraulic leaks and pressure faults

  3. Part 3 · Managing it

    Coming soon

  4. Part 4 · What's next

    Coming soon

Hydraulics · See the Flight Path →

What you will be able to do

  • ✓ Explain why transport aeroplanes use hydraulic power and apply force = pressure × area and flow = speed × area to actuators at 3,000 and 5,000 psi.
  • ✓ Distinguish hydraulic fluid families, their seal compatibility and contamination by particles, water, chlorine and air, and interpret a fluid sample report.
  • ✓ Describe a three-system twin-jet architecture with engine-driven and electric pumps, power transfer unit and ram air turbine, using the official findings on United Airlines Flight 232.
  • ✓ Explain reservoirs, accumulators, filters, priority valves and fuses, and correct an accumulator pre-charge for temperature.
  • ✓ Apply the §25.1435 and §25.1309 requirements and the safe practices for depressurising, servicing and handling phosphate-ester fluid.
  • ✓ Isolate leaks, cavitation, overheating and low-pressure warnings, and decide when minimum equipment list relief does and does not apply.

Course content

Session 1 · Why hydraulics: pressure doing work

1.1

  1. Why aircraft use hydraulics · free preview
  2. Pressure, area and force
  3. The basic circuit
  4. Worked example: sizing an actuator at 3,000 and 5,000 psi
Session 2 · Hydraulic fluids and contamination

1.2

  1. Fluid families and why they never mix
  2. Contamination: particles, water, chlorine and air
  3. Sampling and condition monitoring
  4. Worked example: reading a fluid sample report
Session 3 · Architecture and power sources

1.3

  1. Three systems, shared users
  2. Pumps: engine-driven, electric and air-driven
  3. Back-ups: power transfer unit, ram air turbine and higher-pressure designs
  4. From the investigation file: United Airlines Flight 232
Session 4 · Storing, cleaning and protecting

1.4

  1. Reservoirs and pressurisation
  2. Accumulators and pre-charge
  3. Filters, priority valves and fuses
  4. Worked example: correcting accumulator pre-charge for temperature
Session 5 · Certification, servicing and safety

1.5

  1. How hydraulic systems are certified
  2. Servicing and depressurising safely
  3. Phosphate-ester fluid: skin, eye and injection hazards
  4. Worked example: servicing a reservoir to the right quantity
Session 6 · Faults, troubleshooting and dispatch

1.6

  1. Leaks and the leak-rate check
  2. Cavitation, aeration and overheating
  3. Minimum equipment list relief
  4. Worked example: isolating a low-pressure warning

Who this course is for

  • Engineers new to transport aeroplane hydraulics who need the architecture and its numbers
  • Technicians servicing reservoirs, filters and accumulators with phosphate-ester fluid
  • Maintenance control staff deciding when hydraulic MEL relief does and does not apply

You need: Basic aircraft systems knowledge and simple physics (force, pressure and area).

Upskill courses are for professional development and are not approved by any aviation authority. Learner Terms

Course content © Aerospace Garage Limited. All rights reserved.