B. Disconnect electrical connector from pressure switch (Fig. 401).
C. Unscrew pressure switch and install protective cover.
4. Install Pressure Switch
A. Install backup ring, 0-ring and backup ring in groove on pressure switch (Fig. 401). Lubricate 0-ring and threads with assembly lube or hydraulic fluid.
B. Install switch in modular unit and apply a torque of 50 to 200 pound-inches.
C. Install lockwire on pressure switch.
D. Install electrical connector.
E. Pressurize standby hydraulic system and check pressure switch for leaks.
(1)
Connect electrical power to airplane.
(2)
Close standby pump circuit breakers on P6-11 and P6-12 panels.
WARNING: PERSONNEL STAND CLEAR OF RUDDER AND LEADING EDGE DEVICES.
(3)
On overhead panel, position system A flight control switch to STBD RUD and cycle rudder.
(4)
Place switch in OFF position and remove electrical power.
F. Service hydraulic reservoirs. Refer to Chapter 12, Hydraulic Fluid Servicing.
500
Feb 15/73 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 29-21-81 Page 401
F87802
Standby System Low Pressure Switch Installation 500
29-21-81 Figure 401 Feb 01/75
Page 402
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
HYDRAULIC PRESSURE INDICATING SYSTEMS - DESCRIPTION AND OPERATION
1. General
A. Two hydraulic pressure indicating system s provide remote indication of fluid pressure in hydraulic power systems A and B. Each hydraulic pressure indicating system consists of a transmitter and an indicator for remote indication of pressure. The transmitters are mounted on the forward bulkhead in the left and right wheel wells, and are connected to the pressure side of systems A and B modules by hydraulic connecting lines. The transmitters sense pressure changes and send corresponding electrical signals to a dual pressure indicator on the first officer's panel. The pressure indicating systems are powered by 28 volt ac from the load control panel (P6) (Fig. 1).
F87809
500 Hydraulic Pressure Indicating System Schematic
Nov 15/67 Figure 1 29-31-0
Page 1
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
HYDRAULIC PRESSURE INDICATING SYSTEMS - TROUBLE SHOOTING
1. General
A. The pressure transmitters for systems A and B are installed on the respective system pressure modular units and transmit signals to a dual indicator located on the first officer's panel. The standby hydraulic system is not provided with a pressure indication system, but is equipped with a low pressure warning system.
B. Before trouble shooting system A or system B pressure indicating systems, ensure that the hydraulic system is within design pressure tolerances. Tolerance of the hydraulic reading shown on the dual pressure indicator is +100 psi.
500
Aug 01/94 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 29-31-0 Page 101
2. Trouble Shooting Hydraulic Pressure Indicating Systems HYDRAULIC PRESSURE TRANSMITTERS - REMOVAL/INSTALLATION
TROUBLE PROBABLE CAUSE ISOLATION PROCEDURE REMEDY
High or low Pressure indicator Replace installed indicator with a Calibrate indicator
pressure reading Transmitter tested indicator. Pressurize applicable system and compare readings. Tolerance of indicators is ± 20 psi. If comparative reading between indicators is not in tolerance, removed indicator is defective If comparative reading between indicators is not in tolerance, transmitter is defective or replace Replace transmitter
Zero pressure Open circuit or no Check SYSTEM A-B PRESSURE Close circuit
indication electrical power Transmitter circuit breaker on P6 load control panel Still no pressure indication after ensuring electrical power is applied If electrical circuitry is all right, transmitter is defective breaker Make continuity check Replace transmitter
500
29-31-0 Feb 01/96
Page 102
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
1. General
A. The pressure transmitters for systems A and B are similar units having the same removal and installation procedures, therefore, only one procedure will be given. Both transmitters are mounted on the forward wheel well bulkhead. The system A transmitter is accessible through the left wheel well and the system B transmitter is in the right wheel well (Fig. 401). 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：737 AMM 飞机维护手册 液压 HYDRAULIC POWER(75)
