Table 2-2. Troubleshooting Procedures (Continued)
TEST OR INSPECTION
EXTERNAL LEAKAGE AROUND SHAFT OF CONTROL VALVE (Continued):
Check for enlarged shaft hole caused by side load on shaft.
Replace housing. Temporarily, string packing can be used for seal (para 3-13
EXTERNAL LEAKAGE AROUND SHEAR SEAL SEATS OF CONTROL VALVE:
Check for worn shear seal seat O-ring.
LEAKAGE ACROSS FACE OF SHEAR SEAL SEATS OF CONTROL VALVE:
Check for scratch or other damage to lip of shear seal seat.
Either replace shear seal seat (para 3-13 thru 3-16) or lap face on No. 600 grit
carborundum paper which has been taped to a surface plate or a piece of plate
Check for scratch or damage to rotor.
Lap out scratch on No. 600 paper or if too deep, surface grind rotor, then
lap out as outlined above.
Check for incorrect positioning of rotor in relation to shear seal seat.
Replace detent disc or stop pin, whichever is causing the trouble (para 3-13
Check for extreme wear on face of shear seal seat which will normally occur only
after millions of cycles. Such wear reduces spring tension in shear seal seat and
may thus cause leakage.
Check if shear seal seat spring fails by breaking or taking a permanent set which in
turn, may allow fluid to pass between shear seal seat and rotor.