A.  Skydrol Assembly Lube - MCS 352 or Fire Resistant Hydraulic Fluid - BMS 3-11
3.  Remove System B Fluid Overheat Warning Switch
A.  Depressurize hydraulic reservoirs. Refer to 29-09-300, Hydraulic Reservoir Pressurization System - MP.
B.  Open fluid overheat circuit breakers on P6 load control panel.
C.  Disconnect applicable pump supply line at reservoir to prevent fluid drainage from reservoir when switch is removed (Fig. 401).
D.  Remove electrical connector from switch.
E.  Remove overheat warning switch from switch bushing.
F.  Remove switch bushing and O-rings from tee fitting and install protective cover on open port of
tee fitting.
Install System B Fluid Overheat Warning Switch

A.  Lubricate 0-rings and threaded fittings with assembly lube or hydraulic fluid.
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F87837
Hydraulic Fluid Overheat Warning Switch Installation  500 
29-32-11  Figure 401  Nov 15/67 
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BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

B. Install O-ring and overheat warning switch bushing on open port of tee fitting.
C. Install O-ring and overheat switch in the switch bushing.
D. Lockwire switch to tee fitting (Fig. 401).
E Connect electrical connector to overheat switch.
F Close overheat warning switch circuit breakers on P6 load control panel.
G Connect hydraulic supply line to reservoir.

CAUTION:  WHEN INSTALLING THE PUMP SUPPLY LINE QUICK-DISCONNECT FITTING ENSURE THAT INDICATOR PINS ARE EXTENDED. IF PINS ARE NOT EXTENDED FLUID SUPPLY TO THE PUMP WILL BE RESTRICTED OR COMPLETELY STOPPED AND PUMP DAMAGE MAY RESULT.
H Pressurize hydraulic reservoirs (Ref 29-09-300).
I Operate applicable system B pump. Refer to 29-12-0, Hydraulic System B - MP.
J Check overheat switch and switch bushing for leakage.
K Switch system B pump switch OFF.
L Remove electrical power from airplane.

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HYDRAULIC FLUID QUANTITY INDICATING SYSTEMS - DESCRIPTION AND OPERATION
1.  General

A.  The hydraulic fluid quantity indicating systems indicate fluid quantity in each hydraulic power system reservoir. The system A fluid quantity indicating system consists of a float type level transmitter at the reservoir, and two indicators calibrated in U.S. gallons. One indicator on the first officer's panel, and the other indicator is a direct reading gage in the level transmitter providing fluid quantity indication at the reservoir (Fig. 1). The system is powered by 28 volts dc. A change in reservoir fluid level causes the transmitter float and arm to move up or down. The float arm moves a sliding contact of a variable resistor. The position of the sliding contact of the variable resistor determines the voltage pattern applied to coils in the indicator. The voltages on the coils produce a magnetic field which drives the indicator pointer to show reservoir fluid level. A magnet in the indicator moves the indicator needle "off scale" when there is no electrical power to the system.
B.  Hydraulic fluid quantity indication for system B and standby system is indicated by amber low level warning lights. The system B and standby system reservoirs are normally full and the warning lights are off when the fluid level in the system A reservoir is above the system B balance line connection. If fluid level in either the system B or standby reservoir falls approximately 50% below the full level, the low level transmitter in the affected reservoir will illuminate the low level warning lights. The low level warning light for system B is located on the first officer's panel and the low level warning light for the standby system is located on the pilots' overhead panel.
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Hydraulic Fluid Quantity Indicating System Schematic  500 
29-33-0  Figure 1  Nov 15/66 
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BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

HYDRAULIC FLUID QUANTITY INDICATING SYSTEM - TROUBLE SHOOTING
1.  General

A.  Two basic troubles may be encountered in the hydraulic fluid quantity indicating system. They are an incorrect reading or zero reading of the direct reading gage on the system A reservoir or the remote quantity indicator located on the first officer's panel. The troubles could be caused by an open circuit (no power), defective indicator, or transmitter out of calibration.
　
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