Wherever you have hydraulic equipment, you have the need for regular and thorough maintenance. It's essential that all hydraulic equipment is serviced and checked on a regular basis because of the potential dangers of failure.
In many cases, hydraulic jacks and cylinders are put under an incredible amount of strain on a regular basis. They're often used to lift, move or displace very heavy objects, and so the cost of failure could be high. In fact, life could be a risk if they do fail.
But aside from a full maintenance check on a regular basis, you should also be checking for obvious problems each time the equipment is used. For example, a hydraulic coupling could have failed or become loose during its last use. Or, a leak could have developed when starting a hydraulic pump.
Even small faults should be checked as these can eventually lead to larger, more hazardous problems.