Yellow valve cap Core Back-up ring Pin 5/8-inch hex nut 3/4-inch hex body 3/4-inch hex body 3/4-inch hex body Valve core housing Packing Stem Air orifice O-ring O-ring Valve seat Valve assembly A. Valve core-type  strut fitting AN6287-1 B. Strut fitting with no core MS 28889-1 Figure 13-24.  Valve core-type (A) and core-free valve fittings (B) are used to service landing gear shock struts. 3.  Check the swivel nut for tightness. 4.  If the servicing valve is equipped with a valve core,  depress it to release any air pressure that may be trapped  under the core in the valve body.  [Figure 13-25B] Always be positioned to the side of the trajectory of  any valve core in case it releases. Propelled by strut  air pressure, serious injury could result.  5.  Loosen the swivel nut. For a valve with a valve core  (AN2687-1), rotate the swivel nut one turn (counter  clockwise). Using a tool designed for the purpose,  depress the valve core to release all of the air in the  strut. For a valve without a valve core (MS28889),  rotate the swivel nut sufficiently to allow the air  to escape.  6.  When all air has escaped from the strut, it should be  compressed completely. Aircraft on jacks may need  to have the lower strut jacked with an exerciser jack to  achieve full compression of the strut.  [Figure 13-26] 7. Remove the valve core of an AN6287 valve  [Figure 13-25D]  using a valve core removal tool.  [Figure 13-27]  Then, remove the entire service  valve by unscrewing the valve body from the strut.  [Figure 13-25E] 8.  Fill the strut with hydraulic fluid to the level of the  service valve port with the approved hydraulic fluid. 12. Remove the fill hose fitting and finger tighten the  valve cap of the valve. 11. Once inflated, tighten the swivel nut and torque as  specified. 10. Inflate the strut. A threaded fitting from a controlled  source of high pressure air or nitrogen should be  screwed onto the servicing valve. Control the flow  with the service valve swivel nut. The correct amount  of inflation is measured in psi on some struts. Other  manufacturers specify struts to be inflated until  extension of the lower strut is a certain measurement.  Follow manufacturer’s instructions. Shock struts  should always be inflated slowly to avoid excess  heating and over inflation. 9.  Re-install the air service valve assembly using a  new O-ring packing. Torque according to applicable  manufacturer’s specifications. If an AN2687-1 valve,  install a new valve core. Bleeding Shock Struts It may be necessary to bleed a shock strut during the service  operation or when air becomes trapped in the hydraulic  fluid inside the strut. This can be caused by low hydraulic  fluid quantity in the strut. Bleeding is normally done with  the aircraft on jacks to facilitate repeated extension and  13-13