(e)
If warm, moist air, at a temperature of less than 120°F (48.9°C), flows on the sealant, it decreases the cure time.
S 398-219
(6) If you increase the temperature of the tank structure, but not more than 120°F (48.9°C), it decreases the cure time.
(a) If there is fuel in the tank adjacent to the repair area, you can defuel that tank to increase the temperature of the repair area.
S 398-220
CAUTION: MAKE SURE THE TEMPERATURE OF THE TANK SURFACE TO WHICH YOU
_______ APPLY THE SEALANT IS AT A TEMPERATURE MORE THAN THE AMBIENT TEMPERATURE. CONDENSATION CAN OCCUR AND THE SEALANT WILL NOT DRY CORRECTLY.
(7) For BMS 5-26 Type II sealant, if you keep the humidity constant, the times, shown in Fig. 801, change by these quantities:
(a)
The tack-free times are approximately one-half as long for each 20°F (11.1°C) increase in temperature.
(b)
The tack-free times are approximately double for each 20°F (11.1°C) decrease in temperature.
TASK 28-11-00-398-240
5. Repair of Sealant Leaks in the Fuel Tank Structure
__________________________________________________
A. General
(1) This task has instructions to do a permanent repair of a damaged seal on the internal surface of an integral fuel tank. You must apply a new seal if you do not find a seal. These primary steps are necessary:
(a) Prepare to go into the tank.
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A 737-300/400/500MAINTENANCE MANUAL
SEALANT CLASS HOURS TIME (MINIMUM) APPLICATION 1 HOURS TIME TACK-FREE (MINIMUM) 1 HOURS OUT LIFE (MINIMUM) SQUEEZE-1 HOURS TIME CURING (MINIMUM) 1
PROSEAL 860 3 B-1/6 1/6 1.5 2 -- 4
PR-1828 PR-1826 64 4 B-1/4 1/4 1 -- 2
B-1/2 1/2 2.5 -- 3
BMS 5-45, TYPE II B-1/2 7 1/2 8 -- 24
B-2 2 24 6 48
BMS 5-26, TYPE II A-2 (Grade 1) 2 36 -- 72
A-2 (Grade 2) 2 24 -- 48
B-1/2 7 1/2 6 -- 24
B-2 2 24 6 48
C-24 5 8 -- 24 168
C-48 5 12 -- 48 336
C-168 5 48 -- 168 1,344
AT 77`F (25`C) AND 50% RELATIVE HUMIDITY AMBIENT CONDITIONS. OTHER TEMPERATURE AND RELATIVE HUMIDITY CONDITIONS WILL CHANGE THE TIMES.
DO NOT LET FUEL TOUCH THE SEALANT UNTIL IT IS NOT TACKY FOR A MINIMUM OF 2 HOURS.
WHEN YOU USE PROSEAL 860, DO NOT USE A PRECOAT. PROSEAL 860 IS RECOMMENDED FOR SMALL REPAIRS ONLY,
DUE TO ITS SHORT APPLICATION TIME. AVAILABLE FROM COURTAULDS AEROSPACE, GLENDALE, CALIFORNIA.
USED TO REPAIR FILLET SEALS OF BMS 5-26 OR BMS 5-45. AVAILABLE FROM COURTAULDS AEROSPACE,
GLENDALE, CALIFORNIA.
USED WITH FAYING SURFACE SEALS THAT HAVE A LONG SQUEEZE-OUT LIFE
THIS SEALANT IS WHITE. THUS, IT IS EASY TO SEE THE REPAIRED AREA.
MIX BMS 5-26 OR BMS 5-45, TYPE II, CLASS B-2 SEALANT WITH A 20:100 ACCELARATOR/BASE RATIO BY
WEIGHT OR GET THIS SEALANT PRE-MIXED.
Sealant Usable Time
Figure 801
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(2)
(3)
(4)
A
737-300/400/500MAINTENANCE MANUAL
(b)
Remove the corrosion protection finish (topcoat) if it is necessary to get access to sealant that you must repair
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