Definitive Guide to Aerospace Hydraulic Systems and Maintenance
The aerospace industry demands reliable hydraulic systems to build, maintain and overhaul a variety of aerospace technologies. Hydraulics offer unmatched precision and power that can be scaled to any application.
In this definitive guide to aerospace hydraulic systems and maintenance, we’ll address the most important pieces to every aerospace hydraulic system and how to protect those components from contamination or failure.
Key Hydraulic Components for Aerospace Manufacturing and Maintenance
The aerospace industry is highly dependent on hydraulic systems in nearly every manufacturing and maintenance application. In particular, the following hydraulic equipment technologies are essential in the aerospace industry:
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- Hydraulic pumps – Hydraulic pumps drive other tools necessary for aerospace manufacturing and maintenance. In aerospace applications, hydraulic pumps should be selected for their pressure and flow characteristics to ensure adequate power delivery to each actuator and tool. Valve design and durability features are also considerations of note.
- Hydraulic actuators – Hydraulic actuators, also termed hydraulic cylinders or hydraulic jacks, are responsible for converting fluid power into linear force. Actuators are used for positioning and securing aerospace components, which is essential for maintenance applications. When selecting hydraulic actuators, key considerations include capacity and durability. The capacity to lift and position material (in tonnage) and the durability to hold up over repeated applications of force are vital. Look for hydraulic cylinders manufactured with solid steel construction, alloy bearings for resisting wear, nickel-plated rod components for corrosion protection and expanded size springs to reduce wear during stroking.
- Hydraulic servo valves – Hydraulic servo valves are responsible for precisely metering hydraulic flow to actuators and other hydraulic system components. They’re essential for precision aerospace applications, and when selecting servo valves for your task, choose them for their response time and tolerance.
- Hydraulic pumps – Hydraulic pumps drive other tools necessary for aerospace manufacturing and maintenance. In aerospace applications, hydraulic pumps should be selected for their pressure and flow characteristics to ensure adequate power delivery to each actuator and tool. Valve design and durability features are also considerations of note.
In addition to the above, aerospace companies also rely heavily on hydraulic bolting tools like torque wrenches and bolt tensioners. These are necessary for securing fasteners and ensuring they are properly torqued to safety standards.
Preventing Hydraulic Fluid Contamination in an Aerospace Setting
Hydraulic fluid contamination is a factor in nearly all hydraulic system failures. When microcontaminants are present, it will adversely affect the fluid’s flow characteristics, leading to an array of potential issues, including overheating or cavitation. Therefore, it is a priority for aerospace maintenance engineers to prevent contamination, usually with protective measures like these:
- Routine hydraulic fluid analysis – Hydraulic fluid quality is one of the most important indicators of overall hydraulic system health. As such, it’s important for operators to regularly get a sample and send the fluid sample for analysis. While some signs of contamination can be detected through visual analysis only (water or solid contamination may appear cloudy or milky), deeper lab analysis is usually needed to confirm the early signs of contamination.
How often should aerospace companies send a hydraulic fluid sample out for analysis? It depends on the nature of your worksites and how heavily your hydraulic equipment is cycled. In general, fluid samples should be sent out at least once every few months.
- High quality filtration systems – High quality hydraulic filters are capable of removing microscopic particles and should be installed in-line and to the manufacturer’s specifications. Check these filters regularly to verify that they are in good operating order. Many hydraulic filters are designed with indicators that trigger when it’s time for replacement. Respond to these indicators promptly to maintain hydraulic fluid quality.
- Prioritize proper cleaning and storage procedures – Most hydraulic contamination is introduced into the system via the surrounding environment. To minimize risk of introducing contamination into your hydraulic fluid, prioritize cleanliness with your hydraulic equipment. That includes wiping down your hydraulic pumps and actuators following use and storing them properly when not in use. For actuators, store them with the piston fully retracted into the barrel and the ports sealed. Secure them to prevent them from moving around. If they will be stored long-term, fill them with fresh hydraulic fluid and bleed out any air.
- Regular hydraulic system flushing – It will occasionally be necessary to flush out your hydraulic equipment, which will push out any contamination and prepare the system for a deeper cleaning. When flushing the system, first drain the old hydraulic fluid out and wipe down the interior surfaces of the pump’s reservoir. Once cleaned, replace any hydraulic filters and refill the pump with a clean batch of low viscosity hydraulic fluid. Circulate this through every part of the hydraulic system to maximize contaminant removal, then drain this fluid from the system as well.
Hydraulic fluid flushes aren’t intended to be done regularly. Instead, they should be performed in response to certain events, like following a repair or full inspection. A flush is also recommended when contamination is suspected.
- On-time system inspection and component replacement – Overly worn components are at an elevated risk of sudden, catastrophic failure. However, before a failure, they can also damage overall performance by hampering power delivery or by leaching contaminants into the system. The only way to prevent excessive component wear from affecting your system is to schedule on-time equipment inspections, typically in accordance with manufacturer-specified maintenance intervals.
During a full system inspection, your hydraulic technician will open up the hydraulic pump or actuator and check for any impending signs of failure. High risk parts include seals, gears, bearings, valves and the actuator’s rod components.
- Routine hydraulic fluid analysis – Hydraulic fluid quality is one of the most important indicators of overall hydraulic system health. As such, it’s important for operators to regularly get a sample and send the fluid sample for analysis. While some signs of contamination can be detected through visual analysis only (water or solid contamination may appear cloudy or milky), deeper lab analysis is usually needed to confirm the early signs of contamination.
Essential Maintenance Routines for Hydraulic Equipment
Hydraulic equipment is characterized by its reliability and performance if it’s properly maintained. On-time hydraulic maintenance is particularly important in the aerospace industry, where any system failure can delay operations for an extended time. To prevent downtime from affecting your hydraulic technology, the following maintenance routines are necessary:
- Hydraulic fluid management and inspections – Hydraulic fluid is the lifeblood of every hydraulic pump and actuator system. The cleaner the fluid is the smoother your hydraulic technology will run. Contamination control is a major priority for the aerospace industry, and that starts with regular hydraulic fluid inspections. Check fluid levels and quality regularly and control potential contamination in the environment. Fluid temperature is also important to monitor. If it heats up too much, hydraulic fluid will decline in performance and cause additional problems.
The first rule of proper hydraulic equipment maintenance is maintaining fluid levels and quality. - On-time component replacements (including seals) – Component wear is also a concern for aerospace hydraulic equipment. For example, excessively worn seals will eventually pose a weak spot in the hydraulic system and allow contamination to enter the system. During every service interval, it’s recommended that an expert technician perform a full inspection and check for any worn parts.
- Timely hydraulic filter replacement – Hydraulic filters must be replaced on time. Check the filter indicators for when service is necessary and clean them or replace them during every round of maintenance.
- Regular hydraulic system calibration – Many hydraulic system issues are simply a matter of improper calibration. For example, the system’s relief valves should be pressure checked to verify safety and proper operation. Further, check that the system’s valves are aligned with the pump and other inline components, as this will minimize wear.
- Partner with a proven hydraulic technician expert – Ultimately, most aerospace companies partner with an experienced hydraulic technician to support their hydraulic assets. There are numerous benefits to partnering with an expert hydraulic technician, including accurate troubleshooting and diagnostics, faster system repairs and access to an expanded range of hydraulic parts and components. Altogether, this will extend your equipment’s lifespan and optimize its operating performance.
- Hydraulic fluid management and inspections – Hydraulic fluid is the lifeblood of every hydraulic pump and actuator system. The cleaner the fluid is the smoother your hydraulic technology will run. Contamination control is a major priority for the aerospace industry, and that starts with regular hydraulic fluid inspections. Check fluid levels and quality regularly and control potential contamination in the environment. Fluid temperature is also important to monitor. If it heats up too much, hydraulic fluid will decline in performance and cause additional problems.
If your hydraulic equipment is maintained to these standards, it will be easier to catch emerging technical issues before they bring down your operations and force expensive repairs.
Selecting a Supplier and MRO Provider
Aerospace manufacturing and maintenance rely on hydraulic equipment to get the job done, and that means consistently investing in new and replacement hydraulic components, as well as their associated maintenance.
In order to minimize supply and maintenance costs, aerospace companies typically partner with a single hydraulic equipment supplier and MRO expert that can provide all necessary equipment services – including maintenance, repairs, overhauls and supply.
If you’re searching for a hydraulic supplier and MRO provider, experience is an obvious advantage, but this experience should include work with aerospace clients. Industry specific evidence means a supplier and MRO provider who is familiar with the unique needs and requirements for aerospace manufacturing and maintenance. This experience is essential in properly identifying, selecting and calibrating hydraulic equipment for your application, which adds up to better overall value out of your hydraulic equipment assets.