(4)
If surface was previously topcoated, remove all topcoat from sealant repair area unless it is known that topcoat consists of BMS 10-20, Type II finish material.
(a)
Using abrasive paper, remove old coating until either bare metal or sealant (in good condition) is exposed.
WARNING: DO NOT GET SOLVENT IN MOUTH, EYES, OR ON SKIN. DO NOT BREATHE THE FUMES FROM SOLVENT. SOLVENTS ARE HAZARDOUS MATERIALS. REFER TO PRODUCT MATERIAL SAFETY DATA SHEETS (MSDS) AND LOCAL REQUIREMENTS FOR PROPER HANDLING PROCEDURES.
(b)
Clean all surfaces, including sealant, from which topcoating was removed using clean gauze pads saturated with B01013 solvent, series 93 (Ref AMM/SOPM 20-30-93).
(c)
Wipe dry with clean gauze pad.
(d)
Repeat step (b) and (c) until drying gauze remains clean.
(5)
Remove all old sealant precoat from repair area unless it is known that precoat is BMS 5-26, Type II or Proseal 860 material in good condition.
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WARNING: DO NOT GET SOLVENT IN MOUTH, EYES, OR ON SKIN. DO NOT BREATHE THE FUMES FROM SOLVENT. SOLVENTS ARE HAZARDOUS MATERIALS. REFER TO PRODUCT MATERIAL SAFETY DATA SHEETS (MSDS) AND LOCAL REQUIREMENTS FOR PROPER HANDLING PROCEDURES.
(a)
Remove old precoat with abrasive pad and B01013 solvent, series 93 (Ref
AMM/SOPM 20-30-93).
(b)
Clean surface with clean brush and gauze pads saturated with B01013 solvent, series 93 (Ref AMM/SOPM 20-30-93). Cleaning area should overlap adjacent sealant area so that total area is at least twice as wide as area to be covered with sealant.
(c)
Apply B01013 solvent, series 93 (Ref AMM/SOPM 20-30-93) with saturated gauze pad; then wipe dry with clean, dry gauze pad. Repeat until drying gauze remains clean.
(6)
Ensure that all fasteners in area of sealant repair are installed and tight unless assembly after application of faying surface sealant is required before final fastener installation and tightening. Retorquing of bolts after sealing is not permitted in most cases.
(7)
If alodine metal surface treatment has been worn off or damaged, the metal surface must be realodized before new sealant or finish material is applied.
CAUTION: USE ONLY ALODINE 600 TO REPAIR ALUMINUM WING SURFACES. PRIMER ADHESION PROBLEMS CAN OCCUR IF OTHER ALODINE SOLUTIONS ARE USED.
(a) Apply an alodine layer to the surface with Alodine 600 (SRM 51-10-2).
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(8) Immediately prior to applying sealant, clean surface with BMS 11-7 solvent and wipe dry.
NOTE: Do not allow cleaners to dry on surface. Do not touch area with fingers.
D. Prepare, Apply, and Cure Sealants and Corrosion Resistant Finish
(1)
The importance of mixing, handling, or storing of sealants or finish material cannot be over-emphasized. Deviations from accepted procedures are not permitted since a poor seal may cause loss of an airplane and human lives. Mix components thoroughly as directed by the manufacturer. Do not mix brush type sealants until ready to use for they have a short work life. The use of thinners is not allowed in sealant. Keep sealant covered when not used.
CAUTION: IF SEALANT OR FINISH MATERIAL DOES NOT GO ON SMOOTHLY, DISCARD IT TO PREVENT THE POSSIBILITY OF POORLY SEALED OR TOPCOATED REPAIRS.
(2)
Storing Unmixed Sealant Compound
(a) Unmixed packaged sealant stored longer than 6 months is outdated and should be retested prior to using. A satisfactory check for outdated sealant is to mix a container of base material with its curing compound and, at room temperature, determine the time required for a sample application to become tack-free. Compare this time with the maximum allowable tack-free time given in the applicable sealant specification. If this time exceeds the maximum allowable, sealant should be discarded. Sealant should be stored at temperatures between 50°F (10°C) and 80°F (26.7°C) for best results.
(3)
Mixing Sealant Compound
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(a) Mix only the amount of sealant required for the job to be done. A balance scale with graduated weights should be available for mixing unless the small kits with proper amount of curing compound and sealant in one package are used. All equipment used in the mixing process must be clean.
WARNING: SEALANT MATERIALS ARE HIGHLY TOXIC. ALL MIXING MUST BE DONE IN WELL VENTILATED AREAS.
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