S 872-003
(2)
Apply primer to the area you will seal. Use the primer specified in Table 1 for the sealant you will use.
S 392-004
CAUTION: DO NOT SEAL THE SHANK OF LAMP TERMINALS THAT ARE A
_______ SPRING-LOADED PART OF THE BAYONET LAMP SOCKET BASE. SEAL ONLY THE TERMINAL END AND ATTACHED HARDWARE. SEALANT ON THE SHANK LIMITS MOVEMENT OF THE LAMP CONTACT WHICH CAN CAUSE THE LIGHT ASSEMBLY TO BECOME TOO HOT. IF IT BECOMES TOO HOT, A FAILURE CAN OCCUR.
(3)
Use a brush to apply one layer of sealant to the open areas. Make sure you seal all the open areas.
S 392-005
(4)
On ring torque terminals, apply sealant as follows:
(a)
Apply sealant to the side of the terminal which a metal object can hit if it falls (Fig. 202).
NOTE:____Seal each terminal as far as the attached hardware. You can fully seal the attached hardware. If there are barriers between phases or between components, the seal must extend into the space given protection by the barriers.
(b)
If the edges of the terminals are less than 0.5 inch from each other, apply sealant to the edges.
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A
747-400
MAINTENANCE MANUAL
WHEEL WELL
PRESSURE BULKHEAD
NOSE WHEEL WELL
TRAILING EDGE AREA
LEADING EDGE AREA
ENGINE COWL ENGINE COWL ENGINE STRUT ENGINE STRUT
FUEL VAPOR AREAS:
Fuel Vapor Areas
Figure 201
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A
747-400
MAINTENANCE MANUAL
SEAL ALL OPEN METAL ON THIS SIDE
Sealant Installation on Ring Tongue Terminals
Figure 202
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A
747-400 MAINTENANCE MANUAL
COAXIAL CABLE - MAINTENANCE PRACTICES
_____________________________________
1. General_______
A. The subject that follows describes how to use a time domain reflectometer (TDR; Tektronix Model 1502B) to do a check of coaxial cables. The TDR is used to locate opens, shorts, crimps and other defects in coax cables up to 2,000 feet long. The TDR can also be used on twisted pair or parallel wires which are the same length.
B. The TDR transmits pulses of energy down the cable. The TDR then monitors the impedance changes in the pulse energy that is reflected back. You can see these reflections on the liquid crystal display (LCD). You then find failures in the cable from the properties of the waveform shown on the LCD.
C. The TDR has displays to help you. Push the MENU button to get access to these displays. To get out of the MENU function, continue to push MENU until it goes back to the "Normal Operation" mode.
D. The TDR can be operated from a 115-volt ac or 230-volt ac (45 to 440Hz) power source or an optional internal battery pack. A minimum of 5 hours of operation time is available from the battery pack if it is fully charged.
E. To do a check of a cable, you must disconnect the cable at each end. Connect the TDR to one end of the cable. Adapter cables to connect the TDR to the cable must be assembled locally. Use the applicable system wiring diagram to help isolate the failure to a specified connector, cable segment or black box.
F. To find the distance in feet from one end of the cable to a failure, move the cursor on the LCD to the first impedance change. You will see the distance to the failure in the top right corner of the LCD.
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