B. Procedure
S 764-017
WARNING: MAKE SURE THE BOND RESISTANCE IS NOT MORE THAN THE VALUES
_______ SHOWN. BOND RESISTANCE IS VERY IMPORTANT IF A LIGHTNING STRIKE OCCURS.
IF POSSIBLE, USE A METER THAT IS RESISTANT TO EXPLOSION. IF NOT, MAKE SURE THE DANGEROUS GAS CONTENT OF THE ATMOSPHERE MEASURED BY A COMBUSTIBLE GAS DETECTOR IS LESS THAN 10 PERCENT OF THE LOWER EXPLOSIVE LIMIT.
(1) Install again or replace the fittings which have resistances more than the values in Fig. 404 and 405.
(a) Again do a check on resistance. Do not use bonding jumpers to bridge high-resistance hydraulic installations.
S 764-018
(2) Measure the resistance between the bulkhead fittings and hydraulic tubes (Fig. 407). Make sure the resistance is less than the value in Fig. 404.
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747-400 MAINTENANCE MANUAL
S 764-019
(3) Measure the resistance across the in-line union/tee fittings (tube-to-tube) (Fig. 408). Make sure the resistance is less than the value in Fig. 405.
TASK 20-11-05-054-024
5. Installation of Flareless Fittings in Pressurized Areas, Fuel Tanks, or Cargo
_____________________________________________________________________________ Areas
_____
A. Procedure
S 434-021
(1) Tighten flareless fittings with BACS13AP sleeves two times (tighten, loosen, and tighten again).
NOTE: Be careful to make sure that the fittings will not have leaks
____
after you tighten the fittings.
S 434-022
(2) Tighten flareless fittings with BACS13BX, BACS13BD, welded-on or NAS1760-type sleeves as follows:
(a)
Tighten the fitting to the torque specified in Fig. 403.
(b)
Loosen the fitting to release the torque.
(c)
Tighten the fitting to the torque specified in Fig. 403.
NOTE: Be careful to make sure the fittings will not have
____ leaks after you tighten the fittings.
S 764-023
(3)
WING FUEL TANK INSTALLATIONS; Do the paragraph, Electrical Resistance Specifications in the Fuel Tank.
(4)
Make necessary repairs. Refer to AMM 20-11-05/801.
S 794-025
(5)
Do a leak test:
(a)
Pressurize the system for a minimum of 5 minutes.
(b)
With the system pressurized, rub the tube and fitting with a clean white cloth to find leakage.
S 304-024
NOTE: You can tighten again to the torque value specified
____ above, if you find leakage. If leakage occurs in subsequent leak tests, you must replace appropriate parts.
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747-400 MAINTENANCE MANUAL
S 714-045
(6) If you disconnected more than one hydraulic tube and you think there is a possibility you connected the tubes incorrectly or cross-connected the tubes, do an operational check:
NOTE: Use your own judgement to determine if a check is necessary.
____
(a) Do the post-installation test of one or more components to which the tubes are connected as a check.
S 714-046
(7) If you disconnected electrical wires to get access to the tubes and you think there is a possibility you connected the wires incorrectly or cross-connected the wires, do an operational check:
NOTE: Use your own judgement to determine if a check is necessary.
____
(a) Do the post-installation test of one or more components to which the wires are connected as a check.
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