NOTE: Bleed valves that cannot be freed by lubrication and bleed valves that need frequent lubrication should be removed and overhauled as given in CMM 75-32-01.
(1)
Inject 4 - 6 ounces of approved lubricant into the muscle line to the valve at the nearest connection.
(2)
Apply 100 psig of air or nitrogen to make sure there is flow into the valve. This will also exercise the valve.
(3)
Permit the product to soak for 30 minutes.
(4)
Connect the muscle line again.
(5)
Start the engine and exercise it several times up to the bleed close point to permit the valve to open and close.
NOTE: The only lubricant approved for this application is WC-393. This is the only product known to P&W which keeps its lubricating properties at engine operating temperatures without gumming or coking (which can result in increased seizing of the valve).
WC-393 lubricant can be obtained from the source that follows: Aviation Fluids Services, Inc. 950 Kingsland Ave. St. Louis, MO 63130 Phone: (800) 325-4720 or
(314) 721-2910
P&W 75-30, Page 603/604, May 1/99
500
75-31-0 Page 602 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. May 01/00
START BLEED CONTROL VALVE - REMOVAL/INSTALLATION
1. Removal/Installation Of Start Bleed Control Valve (Engine Incorporating SB 5425)
A. Removal (Fig-401)
(1)
Remove bleed control Ps4 tube between start bleed control valve and bleed control Ps4 manifold.
(2)
Remove bleed control Ps4 tube between start bleed control valve and diffuser outer duct boss.
(3)
Unbolt and remove start bleed control valve from flange bracket.
B. Installation
(1)
Install start bleed control valve on bracket at Flange H and bolt in place, angled fitting facing forward.
(2)
Install bleed control Ps4 tube between start bleed control valve and diffuser outer duct boss.
(3)
Install bleed control Ps4 tube between start bleed control valve and bleed control Ps4 manifold.
500
Feb 20/87 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 75-31-01 Page 401
Start Bleed Control Valve Installation 500
75-31-01Page 402 Figure 401 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. Feb 20/87
PRESSURE RATIO BLEED CONTROL - DESCRIPTION AND OPERATION
1. Description and Operation of Pressure Ratio Bleed Control
A. The pressure ratio bleed control is located on the lower right side of the engine at the diffuser section.
B. Compressor discharge air (Ps4) is routed to the pressure ratio bleed control mounted on the outside of the engine. This unit operates so as to schedule the bleed valve operation as a function of the pressure rise across the front compressor. Senses utilized are inlet total pressure (Pt2) and compressor discharge static pressure (Ps3).
C. Ps3 is ported through a two-stage nozzle system and the resultant sense, upstream of the second nozzle moves a diaphragm against Pt2 and spring pressure. Any change from the schedule position of the diaphragm produces a corrective action by varying the low pressure bleed valves. This is accomplished by a yoke which transmits the signal from the diaphragm to a transfer valve assembly consisting of poppet valves linked together. Movement of these valves directs high compressor discharge air (Ps4) to a "servo valve" which in turn moves to port actuating air to the manifold which supplied the individual bleed valves.
500
Feb 15/67 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 75-31-11 Page 1
PRESSURE RATIO BLEED CONTROL - REMOVAL/INSTALLATION
1. General
A. Refer to 72-00, Removal/Installation, P&WA Maintenance Manual for information concerning general maintenance.
2. Removal/Installation of the Pressure Ratio Bleed Control Tubes
A. Removal (Fig. 401, 402, 403)
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