(1) Seal around fasteners (Fig. 208).
13. Protection of Sealing Materials
A. Sealing materials shall be kept free of contamination by grease, oil, dirt, metal chips, etc.
B. Operations subsequent to sealing may be performed immediately after sealing if care is taken to prevent the sealing from being dislodged, contaminated or damaged. Masking with some removable material may be used to provide protection after sealant is tack-free.
14. Accelerating Curing
A. Curing of two part materials is greatly retarded by temperatures below 60°F and/or relative humidities below 40%. The curing may be accelerated by one of the following methods:
(1) External curing (application of heat may be used to accelerate the cure of sealant already applied. Heat may be furnished by the use of hot air blower, heat lamps, etc.) or prewarning the structure.
CAUTION: IF THE TEMPERATURE OF THE SEALANT EXCEEDS 120°F BUBBLING WILL OCCUR.
500
51-31-0 Page 214 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. Nov 01/75
F85763
500 Fastener Sealing for Corrosion Protection
Nov 01/75 Figure 208 51-31-0
Page 215
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
AIRFRAME DRAINAGE - DESCRIPTION AND OPERATION
1. General
A. External drain holes and internal drain paths are provided to prevent water and other fluids from collecting within the airplane which could become a possible fire or corrosion hazard. Drain paths and and drain holes must be inspected periodically to ensure they are clear of obstructions.
2. External Drains (Fig. 1)
A. Drain ports are located on exterior surfaces of body, wing, and empennage to dump fluids overboard. Leveling compounds is used to ensure proper drainage in sloping areas. Spring or removable drain valves are used in pressurized areas. The seals close off ports when the airplane is pressurized and allow ports to remain open when the airplane is not pressurized. Drain ports in nonpressurized areas are always open.
3. Internal Drain Paths and Drain Holes
A. Internal structure is provided with tubes, channels, dams, and drain holes, to direct the flow of fluids toward external drainage points.
(1)
Primary body drain paths are provided in the forward lower body area, in the overwing and wheel well area, and in the aft lower body area.
(2)
Secondary body drain paths are provided to all stringer splice locations. Drain ports in the floor permit fluids to flow to the lower body skin where they are drained overboard.
CAUTION: IF STRUCTURAL REPAIR IS ACCOMPLISHED, ENSURE DRAIN HOLES AND DRAIN PATHWAYS ARE NOT INADVERTENTLY BLOCKED WITH SEALANT.
536 External Airframe Drainage Section 41
Feb 20/90 Figure 1 51-41-0
Page 1
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
EXTERNAL DRAINAGE - INSPECTION/CHECK
1. General
A. All external drains must be checked at regular intervals to ensure proper drainage and prevent a possible fire or corrosion hazard.
2. Equipment and Materials
A. Wiping cloths
B. Mild Cleaner - GMC 528B (Ref 20-30-31)
3. Check External Drains (Fig. 601)
A. Check external drains frequently and keep free from obstructions. If required, clean drains per par. B or C. Repair leveling compound.
(1) Check drain holes with and without valves in areas of body, wing, empennage, nacelle, and control surfaces.
B. Clean Spring Type Drain Valves.
(1)
Using cloth moistened in water-cleaner solution, if required for set soils, remove all soils and obstructions from drains.
(2)
Carefully raise rubber seals or valves from drain ports in pressurized areas and remove soils and other obstructions. Replace defective or deteriorating seals or valves.
C. Clean Removable Drain Valves.
(1)
Remove valve assembly (Ref 51-41-13).
(2)
Clean valve assembly with stiff bristle brush and water cleaner solution. Rinse with clear water.
(3)
Check and clear drain paths in valve retainer, if necessary.
(4)
Check that drain passage in valve assembly is clear and plunger and spring are intact.
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