AIRFRAME
TROUBLESHOOTING HYDRAULIC SYSTEM INTERNAL LEAKS
A QUICK GUIDE TO Robert Peterson | Contributing Author
Here in my town, there is an automobile radiator repair shop with a motto of “A Good Place to
Take a Leak.” It’s a catchy phrase and it might make some of us laugh; however, there is never a good time or place to have a hydraulic leak on a helicopter. External leaks are not so hard to fi nd but internal leaks are another story. Should you suspect that your helicopter has an internal leak, read on for tips to help you locate the cause of the problem.
To Begin The fi rst step is to map the helicopter’s hydraulic system and components by measuring the hydraulic pressure temperature input and return on the hydraulic components, and write them down. This should be done when the system is running normally. This gives us a base line to use when we have to troubleshoot the system. We need to know what normal values are before we can determine if something is not right. We can check the temperatures every month or when
necessary. We can buy a laser temperature-measuring device at the local auto parts store. The dragster racers use them at the track. This device is great in checking the temperature of the surface of the dragster track to know what kind of tires to use. This measuring device is accurate enough to use on our hydraulic system components.
What Are the Signs? Is the hydraulic system showing signs that all is not well? Is the fl uid temperature hot and we can smell it? Is there discoloration of the fl uid in the reservoir sight glass and paint blistering on any of the hydraulic components? In the case of hydraulic pumps, check inlet suction temperature and then check pressure temperature. Looking at the picture of the hydraulic pump, the suction line going into the pump is bigger than the pressure out line. A normal hydraulic pump temperature should be at system temperature that is called out in the ICA for that model helicopter system. If the temperature shows an increase between pressure and return, this indicates the pump is leaking internally and is too hot to touch with your hands.
Irreversible Valve Assembly Hydraulic Pump
6
HelicopterMaintenanceMagazine.com April | May 2015
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