Aerospace Hydraulic GSE: Maintenance and Troubleshooting Part 1

Aerospace Hydraulic GSE: Maintenance and Troubleshooting
Part I – Types of Contamination

aerospace hydraulic GSE equipment

Aerospace aircraft are serviced and maintained by ground service equipment (GSE), with service carts that connect to the aircraft on the ground to support maintenance requirements, repair or replace components. Aerospace GSE supports many intricate systems with service repair carts equipped with hydraulic test stands, compressors, nitrogen, cooling air and various components such as hydraulic quick couplings. Hydraulic aircraft GSE must be properly maintained according to the OEM operations manual to provide trouble-free service and to prevent catastrophic and costly problems.

Aircraft Hydraulic GSE and the Need for Preventive Maintenance

Maintaining aerospace GSE extends equipment life, reduces the frequency of unscheduled maintenance, and reduces overall lifecycle costs. Hydraulic GSE equipment that interfaces with the aircraft could contaminate and damage sensitive aircraft hydraulic components if not properly maintained. Checking for hose and seal integrity, checking fluid levels, checking for leaks, and preventing contamination are some of the tasks performed during regular maintenance of hydraulic GSE equipment.

Many aircraft GSE systems include hydraulics such as:

  • Hydraulic Power Units
  • Reservoir Service Units (Engine Oil and Hydraulic Oil)
  • Hydraulic Jacks
  • Hydraulic Test Units
  • Towbars with Hydraulic Height Adjustment
  • Hydraulic Cranes
  • Hydraulic Maintenance Platforms
  • Ground Test Units of Emergency Power Systems
  • Hydraulic Wheel and Brake Dollies
  • Hydraulic Tire Bead Breakers

Preventing Contamination in Hydraulic GSE Is Critical

Preventing contamination should be the foundation of any preventive maintenance plan for hydraulic GSE. In-depth training for all personnel involved is a mandatory part of any contamination prevention program and can be performed by the equipment manufacturer, the School of Engineering or the Fluid Power Training Institute. All hydraulic GSE equipment should have a baseline fluid sample with testing performed from an independent laboratory or with a contamination monitor.

Fluid testing should be performed at specific intervals along with regular filter replacement to help prevent contamination in hydraulic GSE. Not all systems interface with the aircraft, closed systems still require inspection and maintenance such as checking for fluid leaks, checking fluid levels and obtaining fluid analysis at predetermined frequencies unless troubleshooting.

Contamination Problems in Hydraulic GSE Fluid

When aircraft GSE experiences hydraulic fluid contamination, it is either from one of four major categories:

  • Particles, solid foreign material in the fluid
  • Water, free water or in a solution
  • Chemical, from a foreign source or fluid deterioration
  • Air, either entrained or dissolved


Particle contamination in hydraulic fluid can cause accelerated system wear or complete component failure. Foreign particles can cause abrasive wear on moving components and deteriorate surfaces. Solid particles can plug systems with tight operating clearance and cost unintended equipment shutdown.


Moisture causes chemical reactions with hydraulic fluid and can lead to interference of performance and increased system wear. Water contamination of hydraulic fluids may cause a galvanic action promoting rust and corrosion; this corrosive action causes surface degradation and fatigue.


There are many potential causes to chemical reaction in hydraulic systems such as mixing up hoses and introducing incompatible fluids, a chemical reaction with fluids and components, thermal damage caused from excessive heat, deterioration from additives, excessive mechanical shear, a breakdown of fluid additives or variances in viscosity are some examples.


Air contamination of hydraulic GSE equipment can produce excessive heat with pressure changes that compress the air, this causes premature wear and decreased operating efficiency. Air contamination causes oxidation of metal parts which increases noise level, operating temperature and reduces transmitted power.

These are some of the various methods of contamination that can occur in hydraulic fluid systems in aerospace hydraulic ground service equipment.

Solutions to Prevent Contamination in Hydraulic GSE Equipment

Using the right hydraulic quick couplers for your aircraft hydraulic GSE equipment is critical to prevent contamination. Stucchi is a leading supplier of hydraulic solutions and quick couplings designed for a variety of challenging, heavy duty applications. Our quick couplings for aerospace GSE include threaded couplings, flat face quick disconnect (QD) and multi-coupling plates. Our hydraulic specialists help you choose the best quick couplers for your hydraulic GSE equipment as we customize your solutions to meet your specifications with optimal performance.

Stucchi’s design of the flat face quick coupler set the ISO 16028 standard, as a leader in delivering leak-free quick connect solutions. Our flat face quick couplers eliminate contamination in hydraulic circuits, with a no-spill design that prevents fluid loss on quick connect and quick disconnect. Threaded, flat face quick couplers by Stucchi hold up to heavy-duty, pressurized applications with a thread to connect design that prevents unwanted disconnection.

Multi-coupling plates prevent cross connection and chemical fluid contamination, with easy and reliable quick connect and quick release of multiple lines at once. We offer multi-coupling plates to support the same or different size couplers and the same or different media such as hydraulic fluid, electrical or pneumatic lines.

Stucchi is a recognized industry leader in providing hydraulic solutions to many industries including heavy duty and challenging configurations. We offer a wide selection of hydraulic quick couplers and multi-coupling plates to improve efficiency, safety, prevent leaks and contamination. Contact us to learn more about our hydraulic quick couplers for aerospace hydraulic GSE equipment.