The Importance of Proper Hydraulic Power Unit Maintenance

Posted on April 22, 2021 Jacob Luiz

Hydraulic power units (HPUs), a type of ground support equipment, are crucial for the testing and maintenance of aircraft systems. But like any machine, they cannot be used if they are not in peak condition. This is where preventative maintenance comes into play. By maintaining your HPU prior to its breaking down, you will be able to rely on it whenever you need it. In this blog, we will look at the four most important aspects of HPU maintenance: checking and changing oil, cleaning filters and strainers, checking for leaks, and lubricating the motor.

Checking and Changing Oil

Whenever a motor is involved, oil is among the first things to be checked during maintenance. First, the oil levels, temperature, and viscosity will be measured. There must be enough oil, it must be of the proper consistency, and it must not be too hot. If any of these conditions are off, the motor won’t be able to operate properly and the pump could be damaged.

In addition to these, contaminants and wear must also be checked. Any contaminants in the oil can cause damage to other parts of the system, such as pumps, hoses, and seals, through abrasion. Even without contaminants, oil will wear over time. If this happens, oil will no longer do its job properly, leading to damage. The suggested frequency of oil changes depends on the operation conditions of the motor, but is generally done between 1,000 and 2,000 hours of use. When changing oil, it is also a good idea to have the tank cleaned and checked for damage.

Clean Filters and Strainers

Filters and strainers are used to protect the hydraulic system from contaminants. Over time, if they are allowed to collect too much dirt, they will no longer work properly. Because of this, filters and strainers should be changed on a regular basis. Filters should be changed as needed, and strainers are typically changed after 100 hours of use. In some cases filters can be cleaned rather than replaced, but it is generally better to replace them as this is both easier and less costly.

Checking for Leaks

Leaks can occur anywhere throughout the hydraulic system and have two main effects. For one, they can lead to the loss of hydraulic fluid or oil, leading to damage. Additionally, these leakage points can become entrance points for all types of external contaminants. For this reason, even if a leak isn’t causing your system to lose fluid, it is important to fix them as quickly as possible. The most common places to check for leaks are valves, pipes, connections, seals, hoses, fittings, and tanks.

Lubricating the Motor

In addition to ensuring the motor will operate smoothly, proper lubrication increases its overall lifespan. Each motor manufacturer will provide different instructions for how much and how often the motor should be lubricated. This can get confusing if your ground support equipment includes machinery with motors from many manufacturers, but it is important to determine.

The HPU is the workhorse of your ground support equipment. They provide critical auxiliary power to aircraft systems for maintenance and repair. Without them, your aircraft operation can come to an abrupt halt. For these reasons, proper maintenance of your HPUs is critical.

For all types of ground support equipment and much more, look no further than ASAP Aerospace. Owned and operated by ASAP Semiconductor, we can help you find all types of parts for the aerospace, civil aviation, defense, electronics, industrial, and IT hardware markets. Our account managers are always available and ready to help you find all the parts and equipment you need, 24/7-365. For a quick and competitive quote, email us at or call us at 1-714-705-4780. Let us show you why we consider ourselves the future of purchasing.


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