Aircraft Hydraulic Servicing and Oil Dispensers

One of the critical components of aircraft safety is hydraulic servicing and maintenance. Hydraulic systems are integrated into several flight systems such as engine, fuel, brake, lube, and other auxiliary systems. Therefore, to prolong the life of aircraft and its components, having a standard hydraulic preventative maintenance (PM) schedule is critical. A PM program shall safeguard the components and reduce the costs associated with breakdown repair and downtime losses. Tronair supplies hydraulic products for servicing and replenishing hydraulic and engine oil systems with clean, contaminated free fluid.


Tronair Hydraulic Servicing and Oil Dispensers:

Fluid dispensers are perfect to handle waste fluids, engine oils, hydraulic fluids, and other liquids. The function of fluid dispenser systems is to protect the component against moisture and air-borne contaminants by flushing and servicing the reservoir and component. Following are types of Hydraulic servicing and oil dispensers offered by Tronair:


  1. Hand-held Units: These small units are designed for portable servicing of hydraulic and oil reservoirs. Capacity – 2.5 Gallon.
  2. Service Carts: These compact servicing carts, designed to provide clean fluid for filling reservoirs. Capacity – 5-15 gallon
  3. Service Unit: These are servicing units connected to any standard 55-gallon drum for servicing hydraulic and oil reservoirs. Capacity – 55 Gallons
  4. High capacity Hydraulic and Engine service Cars: Heavy-duty service carts connected with a wheeled base to tow, transfer and store hydraulic oils. Capacity – Up to 150 Gallons.


In addition to providing oil servicing and dispensing kits, Troniar also supplies Hydraulic oil test kits to ensure components are free from solid or air-borne contaminants. Standard oil servicing test units have an 8 Gallon reservoir capacity and are designed to provide pressurized fluid for filling reservoirs, bleeding brakes, or other maintenance functions.


Hydraulic Oil Dispensers – Operation Principle:

Oil Dispensers typically consist of a fluid reservoir, hydraulic pump, filter assembly, and a long fluid delivery hose. The function of each component is as explained below:


  1. Fluid reservoir: Made from ASME certified stainless steel, durable, coated with lightweight polyethylene material impervious to petroleum-based fluids, such as hydraulic fluids and solvents. The function of fluid reservoirs is to store hydraulic and engine oils, with capacities ranging from 5 gallons to 150 gallons.
  2. Hydraulic pumps are either manual (hand-held operations) or pneumatically operated pumps to supply high-pressure fluids to clean hydraulic components and reservoirs. Depending on the application, the discharge pressure is selected and adjusted by varying motor speeds. Typically, these pumps operate at 100 psi (6.9 bar) or 200 psi (13.8 bar) pressures.
  3. Filter assembly: One of the key functions of oil dispensing units is to clean the hydraulic oil and maintain oil cleanliness levels (under ISO 4406 and NAS 1638 standards). To maintain these cleanliness levels, in-line filters are installed at the outlet of pumps to ensure that the hydraulic oil is free from solid and air-borne contaminants. Troniar supplies quality filters tested and approved by ISO 4572 standards with a Beta Ratio of 1000 (99.9% filtration efficiency in capturing solids of 2 Micron or greater size).
  4. Fluid delivery hose: The delivery hose connects Tronair servicing unit to hydraulic components and reservoirs. Typically these are braided or flexible hoses, with design pressure more than the pump delivery pressure.


Several standard and special hose end fittings, couplings, and accessories such as pressure gauges are configured to the servicing and testing kits for multiple hydraulic service applications.


Preventative Maintenance Program for Hydraulic Oil Dispensers:

Preventive Maintenance is technically defined as the process of ensuring that a system shall continually perform its intended function at its designed-in level of reliability and safety. ISO 23309:2007 provides standards on methods of cleaning hydraulic fluid systems and assembled systems by flushing and dispensing.


A hydraulic oil dispensing Preventive Maintenance (PM) program shall involve the following steps:


Step 1:

Identifying the operation frequency and service load. This consists of formulating operational hours, load on pump and service unit, and climate conditions.

Step 2:

Following OEM (Tronair) SOP guidelines on daily and scheduled maintenance activities and PM procedures on the hydraulic system.

Step 3:

Maintaining cleanliness standards of hydraulic oil as specified by OEM and ISO 4406 or NAS 1638 standards. Contamination is measured by periodic lab analysis and oil sensors.

Step 4:

Oil filters – The PM program should assign logbooks to record Beta values by multi-pass filter test or measuring NAS values or particulate contamination of oil after a service. Higher contamination implies filter replacement. An increase in pressure reading also indicates filter choking.

Step 5:

Hydraulic oil grade and brand – Each hydraulic brand has a unique set of additives selected based on the application. Post-service activity, replacing the filter (if the next service is on a new fluid) is necessary to avoid fluid contamination and mixing of additives.

Step 6:

The equipment’s fluid reservoir should be checked for leaking or any damage that could cause a premature rupture of the reservoir.

Step 7:

Hoses should be checked for leaks, cracks, or damage to the connections at their ends. The handle on the manual pump should be inspected to ensure that it is operating correctly and all of the mounting hardware is not missing or loose. If the force required to activate the handle is higher than normal, it could indicate that the filter is clogged and needs to be replaced.

Step 8:

The wheels should be checked for proper ease of rotation and inspected for significant damage. The towing handle or tow bar eyelet should be inspected for any excessive wear, cracks, or deformation.

Step 9:

Pressure gauge installed on the servicing unit shall need regular calibration following manufacturer’s specifications.


Advantages of Preventative Maintenance Program – Why is it essential:

Although establishing and adhering to a PM program requires stringent control measures, they often prove beneficial for the aircraft operator in the long run. Following are few direct and indirect benefits of the hydraulic dispenser PM program:



e2b calibration offers industry-leading consultancy and certified PM services for your aircraft hydraulic servicing and oil dispensers. Our labs are ISO/IEC accredited and operated by a team of qualified experts providing training and consultancy services on Tugs maintenance and inspection. Our verifiable services are unmatched in the industry. Contact e2b calibration for all your equipment calibration needs.



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