TM 55-2840-241-23 5-22           Change 19 Section  IV.   ANTI-ICING AND BLEED AIR SYSTEMS WARNING Failure to properly install, align, and tighten air fittings and tubes could result in an engine fail- ure. 5-31.   Scope. Anti-icing and bleed air systems servicing includes replacing and testing the compressor bleed valve and anti-icing air valve. In addition, it includes anti-icing valve repair. 5-32.   Anti-icing Air Valve.   a.  Removal.   (1) Disconnect air tubes (23 and 26, figure 5-13) at the anti-icing air valve (29). Disconnect the air tubes at the compressor front support only if necessary. (2) Disconnect the aircraft linkage from the valve lever. (3) Remove lockwire , loosen jam nut (24), and unscrew the valve from the diffuser scroll. Discard pre- formed packing (25). b.  Testing.   (1) Apply 100 psig air pressure to the Valve Inlet with a 0.025 inch orifice installed between the air source and the valve inlet after installing gauges to monitor the pressure on both sides of the orifice. (2) Apply 3.75 pounds maximum force to hold the lever in the closed position. (3) Allow air pressure on both sides of the orifice to stabilize, maintaining pressure at the orifice inlet at 100 psig. (4) If the valve leakage is excessive such that the pressure downstream of the orifice decreases, replace the valve and retest. c.  Anti-icing Valve Poppet Seat Replacement.   Replace the Teflon poppet seat of the anti-icing valve as follows: (1) Remove   the   cotter   pin   (17,   figure   5-13), washer (16), and pin (14). Detach the actuating lever (13) from the valve. Discard the cotter pin. (2) Remove the lockwire  and unscrew the pop- pet guide (15) from the valve body (22). Separate the poppet (18) from the body. (3) Remove  the  screw  (21)  and  separate  the poppet seat (20) from the poppet. (4) Clean valve components in  cleaning solvent (3, table  2-2). (5) Inspect valve components per table  5-2. (6) Install the replacement poppet seat (20). Re- tain the seat with screw (21). Stake the screw securely. (See figure 5-14.) (7) Insert the poppet and seat into the valve body (22, figure 5-13) and screw the poppet guide (15) onto the body. Tighten the coupling nut to 65-75 in. lb. Do not lockwire at this time. (8) Align the actuating lever (13) with the hole in the poppet guide (notch in the lever toward the guide) and insert the pin (14). Secure the pin with washer (16) and new cotter pin (17). (9) Recheck   the   valve   for   leakage.   Replace valve assembly if leakage is still excessive. d.  Installation.   (1) Place   new   preformed   packing   (25)   with backed-off jam nut (24) on anti-icing valve (29). Apply antiseize compound (item 15.1, table  2-2)  lightly to the threads and install the valve in the diffuser scroll. Do not tighten jam nut (24). (2) Connect air tubes (23 and 26) to the valve. Tighten the coupling nuts to 150-200 in. lb. Tighten jam nut (24) to 100-150 in. lb. and lockwire (item 10, table 2-2). (3) Loosen poppet guide (15) and position lever (13)  parallel  with  the  vertical  centerline  of  the  engine. Tighten the poppet guide to 65-75 in. lb. and lockwire (item 10, table  2-2). 5-33.   Compressor Bleed Valve.   a.  Testing.     Test the compressor bleed valve while installed on the engine. Turn off all bleed air. (1) Pilot and observer use helmets and exten- sion cord to passenger communication box. (2) Observer use flashlight to view operation of the bleed valve. (3) Run up engine to 100% N2 and observe com- pressor bleed valve operation. Valve should not be fully closed. (4) Apply collective until valve is fully closed. NOTE It may be necessary to increase aircraft gross weight to accomplish run-up. If passengers are  used  to  increase  gross  weight,  ensure that seat belts are fastened for all occupants. WARNING Do  not  have  personnel  stand  on  aircraft skid tubes to increase gross weight.