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Hydraulic Ground Support Equipment Maintenance Guide

Hydraulic ground support equipment can have a long lifespan if maintained and operated properly. This guide will explore some key preventive maintenance that you should regularly conduct on your aircraft hydraulic power units.

If not maintained regularly, your hydraulic ground support equipment (GSE) could potentially contaminate an aircraft's hydraulic system, damaging sensitive components. This guide will walk you through some of the high-level preventive maintenance that should be completed on your aircraft hydraulic power units.

Keep in mind that this guide should be used as a supplement to your original equipment manufacturer's (OEM) maintenance manual.

Before we get started, you should have a firm grasp on the three key elements of proper hydraulic GSE preventive maintenance.

  1. Knowing the condition of the fluid and equipment's components
  2. Keeping contamination levels at an acceptable rate
  3. Operating the equipment in accordance with the OEM manual

Once you understand what goes into the maintenance of your equipment, you can begin to put a thorough program in place.

Did you know that most GSE systems include hydraulics? The following are just a few pieces of hydraulic equipment that may be sitting around your airport.

Setting Up A Contamination Control Program

Prior to delving into anything else, it's vital that you have a comprehensive contamination control program set up. This is the foundation for any successful hydraulic ground support equipment maintenance plan.

Contamination issues in hydraulic GSE fluid can typically be linked back to one of four problems:

  • - Particles
  • - Water
  • - Air
  • - Chemicals

To prevent these contaminants from entering the system, you'll need to ensure that you have a contamination control program in place. Typically, these control programs can be split into six steps.

1. A Company-Wide Agreement Of Support

First, you'll want to ensure that you have a company-wide agreement to support this new contamination control program. This will include an acknowledgment of all things related to the new initiative, including the necessary costs, training, equipment, materials and manual labor.

2. Personnel Training

Then, you'll want to set up training for all employees so they can start the new program on the same foot. Training can be supplied by the equipment manufacturer, a hydraulic training center or a school of engineering. This will ensure that all of your employees have the proper knowledge and skill set needed to keep equipment in pristine working order.

3. Setting Standards For Fluid Level Contamination

Next, you should put in place fluid level contamination standards for all employees to follow. These acceptable levels of contamination should come from the airframe tooling manufacturer's recommendation. But we'll touch more on this a bit later.

4. GSE Baseline Testing

Once your personnel has been trained and a fluid level contamination standard has been put in place, you'll want to conduct baseline testing of all your hydraulic ground support equipment. You can send a fluid sample to an analysis laboratory or use a contamination monitor to find your baseline.

5. Acquiring Equipment & Materials

At this point, you should be acquiring any and all equipment and materials you'll need to implement your new contamination control program. This can include, but is not limited to, the following:

6. Scheduling Maintenance & Testing

Finally, you can begin to schedule regular maintenance and testing of your hydraulic GSE. Things that should be set up include specific intervals for testing and filter replacement, as well as periodic evaluations of the program itself.

Conducting Proper Prevention & Monitoring

As we've mentioned, it's vital that you have regular preventive maintenance scheduled for your airport GSE. The best offense is always a good defense. By taking the proper precautions to prevent contaminants from entering your systems in the first place, you'll find your equipment will last longer and require less unscheduled maintenance. This equates to a lower life cycle cost on all fronts. So, make sure you instill the need for regularly scheduled inspections and maintenance programs.

Inspect Fluids & Contamination Levels

When inspecting fluids, you'll want to begin by making sure the fluid filler cap is in good condition. This cap should only ever be removed when servicing the reservoir. A hydraulic ground support equipment fluid reservoir should typically be a sealed type with an air filter and desiccant in order to control the overall condition of the fluid. If you don't currently have these in place, consider adding an air filter and desiccant system to your already existing reservoir. 

You'll want to regularly monitor your fluid to ensure that it's meeting the required specifications of the airframe, fluid or component manufacturer. Monitoring consists of taking a fluid sample and sending it to an analysis lab or using a portable contamination monitor. This monitoring process allows you to consistently adjust your contamination control and maintenance programs in order to keep contamination at an acceptable level.

By using portable monitors to get immediate results of the ISO or NAS cleanliness level, you'll be able to inspect your hydraulic GSE with top-of-the-line precision. The monitor not only allows you to gauge the cleanliness level but also the moisture level within the fluid system. You'll then want to use a portable filtration and moisture removal unit to bring these down to more acceptable levels that conform with your manufacturer's recommendations. 

Another method for maintaining acceptable levels is to off-line clean your hydraulic fluid system. Simply loop fluid through an onboard or kidney loop system until the levels have reached an acceptable point. 

Replace Filtration Systems

You should be changing GSE filters regularly based on manual recommendations to maintain the required contamination level of the systems. This should be done, at a minimum, on an annual basis. Depending on usage, it may need to be done more frequently. When monitoring the air filter and desiccant, ensure that they're not saturated. This could be limiting air from exchanging with the reservoir or may even allow contaminates to enter the reservoir. 

To take advantage of new, more efficient filter designs, consider upgrading the filtration systems of your hydraulic ground support equipment. Filters should be carefully chosen and able to handle the required system flow and pressure.

Hydraulic System Maintenance & Troubleshooting Checklist

To make life easy for you and your employees, it's always a good idea to put a hydraulic system maintenance and troubleshooting checklist in place for quick reference. Keep in mind, the following is a generic and high-level checklist for hydraulic GSE. You should always consult your equipment manufacturer manual for model-specific instructions.

Quick Reference Troubleshooting Checklist

𝤿 Inspect quick-disconnect couplings and coupling plugs for leaks or damage. [Repair or replace]

𝤿 Check internal and external hoses for wear and damage. [Replace]

𝤿 Look for hydraulic leaks at the fittings, O-rings, gaskets and shaft seals. [Retorque, repair or replace]

𝤿 Ensure fluid filler cap is in proper operating condition. [Replace]

𝤿 Verify that indicator lights are operating. [Repair or replace]

𝤿 Check that cooling fan is operating properly. [Clean, repair or replace]

𝤿 Inspect condition of fluid using lab or portable monitor. [Filter and dehumidify as necessary]

𝤿 Replace fluid filters on a regular basis.

𝤿 Replace air filter/desiccant element on a regular basis.

𝤿 Using the OEM maintenance manual, ensure the hydraulic pump(s) performance.

𝤿 Inspect reservoir fluid level when all cylinders are retracted at operating temperature. [Fill if needed]

𝤿 Check system pressure relief valve setting, referencing OEM maintenance manual.

𝤿 Look at the reservoir's interior for any visible objects or silt buildup. [Drain, clean and refill with new filtered fluid]

𝤿 Run system to purge any entrapped air. Then, circulate at varying flows and pressures. 

If a piece of hydraulic ground support equipment does become contaminated, great care should be taken to ensure that all affected components are replaced or thoroughly cleaned and dried. The contaminated fluid should then be properly disposed of, and a fluid analysis should be done to make sure that all traces of the fluid have been removed from the system. 

Find Hydraulic GSE, Test Equipment & More At Tronair

Tronair offers a diverse and unparalleled selection of high-quality GSE products. Shop for hydraulic ground support equipment, test kits, fluid contamination monitors and more. With over 100 years of experience, our customer service department and sales team are here to help with any questions about our range of products. Contact us today.

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