Safety - Section 22 8/11 OM2221 Page 22-4 FILLING THE HYDRAULIC TANK HYDRAULIC OIL PRESSURE A plate mounted on the side of the hydraulic tank provides instructions for filling the hydraulic tank. A warning plate is attached to the hydraulic tank to warn technicians that high pressure hydraulic oil is present during operation. When it is necessary to open the hydraulic system, be sure the engine is stopped and the key switch is OFF to bleed down hydraulic pressure. There is always a chance of residual pressure being present. Open fittings slowly to allow all pressure to bleed off before removing any connections.
To lessen the chances of system contamination, keep the system open to the atmosphere only as long as absolutely necessary. Service the tank with clean Type C-4 hydraulic oil. All oil that is being put into the hydraulic tank should be filtered through 3 micron filters. A caution decal is attached below the hydraulic tank oil level sight gauge. Check the oil level with the body down, engine stopped, and key switch OFF. Add oil per filling instructions if the oil level is below the top of the sight glass. This warning decal is located near the battery discon- nect switches to warn personnel not to disconnect the batteries during the first two minutes after the engine has stopped.
Turn the key switch to the OFF position and wait for the engine to stop. After the engine has stopped, wait two minutes, and if no warning lights illuminate, then turn the battery disconnect switches to the OFF position. The first two minutes after the engine has stopped is the bleeddown process. Turning the battery disconnect switches off within two minutes could interrupt the bleeddown process and leave stored energy in the accumulator. Wait two minutes after the engine has stopped, then observe for bleeddown malfunction warning message in dash panel. If a warning is being displayed, notify maintenance immediately.
Turning the battery disconnect switches to the OFF position sooner than two minutes could mask a problem that was detected during the bleeddown process.