Backfill Main Canopy Transparency Adhesive
100875-00
Use the following task to seal the areas around the main canopy transparency in order to repair small leaks.
Applicable Aircraft Serial Numbers
All
Type of Maintenance
Line
Level of Certification
LSA-RM
Task Specific Training Required
No
Special Tools Required
None
Parts Required
None
Aircraft System and Number
02—Doors and Windows
Safety Equipment
As Needed
Consumables
AC-137 (ADHESION PROMOTOR, 3M AC-137)
AC-251 (SEALANT, AEROSPACE, BLACK CLASS B, B-1/2)
TT-I-735A or equivalent (ISOPROPYL ALCOHOL)
Mild Soap-Water
Castile, Woolite, Deft, Plexus acrylic cleaner, Brillianize plastic cleaner, or equivalent acrylic-safe cleaner
Repair Notes:
• Blow dust off surface. Use air or water to remove dirt before you begin to clean. You can use canned air to blow dirt off the windows, or drip water onto the surface that picks up the dirt and allows you to float it off.
• Clean the surface using a "2 wipe" practice. Wipe the surface with a new, clean soap-wetted cloth to remove any trace oils, mold release, and particulate matter. Then, clean surface again by wiping down with a new clean cloth. One pass with one cloth is not sufficient.
• Use a non-abrasive cleaner and microfiber cloth on soiled acrylic.
• Mix non-abrasive soap with water, apply to microfiber cloth, and blot acrylic surface. If needed, apply acrylic cleaners directly to surface and blot away with microfiber cloth.
• Nonabrasive cleaners include Castile soap, mild dish soap, Woolite, Deft, Plexus acrylic cleaner, Brillianize plastic cleaner, and equivalent acrylic safe cleaning solutions.
• Do not clean with Alcohol-Methyl, Ethyl, or Acetone. Use of these types of cleaning products or non-acrylic safe cleaners will potentially result in crazing, cracking, cloudiness, or other surface defects.
• Isopropyl alcohol can only be used to clean a transparency surface as a last option. The above acrylic cleaners must be attempted first. Isopropyl alcohol should only be used if the only other option is to scrap the transparency.
Task Instructions
1. Remove LH and RH side windows to access the canopy transparency perimeter as necessary. Close canopy.
2. Clean the area with soapy water, or approved cleaners, and wipe clean with lint-free cloth.
3. Using a popsicle stick and 220 grit sand paper, carefully abrade inside of the Main Canopy Transparency. Be cautious to avoid damaging painted surfaces.
4. Clean the abraded areas with approved cleaners. Ensure that debris has been removed from the bonding surfaces. Let dry.
5. Optional (to decrease cure time): Using the popsicle stick, apply adhesion promoter inside surfaces of the Main Canopy Transparency where adhesive is to be applied.
6. Wipe the surface leaving a clean, wet surface. Allow solvent to flash off after application.
Note:
Bonding should be done between 45° and 95° F to prevent dimensional variations in the transparencies based on temperature.
Note:
Ensure that the work area is ready for the adhesive to be applied and that all tools, consumables, PPE, etc. are quickly within reach. AC-251 B-1/2 adhesive has a minimum application life of 30 minutes at 77° F with a relative humidity of 50%. The application life is dependent on the temperature and humidity of the work environment.
Note:
Mix the cartridges of adhesive one by one as they are needed. Do not mix all of the adhesives at once.
7. Mix adhesive B-1/2 per manufacturer instructions:
a. Holding the cartridge, grasp the dasher rod and pull back approximately one inch.
b. Insert the ramrod into the hollow of the dasher rod, break the piston loose, and inject about 1/3 of the contents into the cartridge. Do not inject all the catalyst into one location. Distribute evenly throughout the base material.
c. Repeat until all the contents of the rod are emptied into the cartridge. Remove the ramrod.
d. Mix the required number of strokes (hand mix: 50-75 strokes) or for the required amount of time (machine mix: 37 strokes or 1.5 minutes at 25 strokes/minute).
e. When mixing is complete, remove bottom cap.
f. Pull the dasher rod back to the neck of the cartridge, grasp the cartridge firmly at the neck, unscrew the dasher rod, and remove.
g. Screw the nozzle into the cartridge, insert into the extrusion gun and use as required.
8. Using a syringe, inject AC-251 sealant at the prepped location and fill the voids as necessary. Do not overfill.
9. Using a mirror and flashlight, verify that there are no voids in the bond line. Fill voids in bond line with AC-251 sealant as necessary.
10. Allow the adhesive to cure for a minimum of five hours at room temperature.
11. After cure is complete, inspect the perimeter of the main canopy transparency for any voids.
Verification Method
Install side windows and pour water over the canopy or spray with a hose to check for leaks through the canopy transparency.
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