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3M Aerospace AC-665 Class C-24 Corrosion Inhibitive Sealant

3M Aerospace AC-665 Class C-24 Corrosion Inhibitive Sealant

Easily prevent corrosion and rust on your aircraft with the use of 3M Aerospace AC-665 Class C-24 corrosion inhibitive sealant from SkyGeek. Made up of a two-part, manganese-cured and chromated compound, this sealant works to block the effects of common corrosion-causing substances. Some of these corrosive substances include chemicals, hydraulic fluids, petroleum products, aviation gasoline and jet fuel. AC-665 sealant works best to protect aluminum alloys and dissimilar metals. Once mixed, this compound becomes a flowable, faying surface-grade material. It can be easily applied using an extrusion gun, brush, spatula or roller. The flexibility and bond strength of the sealant is maintained throughout extreme temperatures, weathering and stress.

Approvals, References and Specifications
  • CSNP-035
  • STM 40-112
  • MIL-PRF-81733 Type IV


  • Two-part corrosion inhibitive sealant
  • Manganese-cured and chromated
  • Effectively protects aircraft against corrosion for aluminum and dissimilar metals
  • Resistant to petroleum products, chemicals, hydraulic fluids, aviation gasoline and jet fuel
  • Mixed compound is flowable, flaying, surface-grade material
  • Apply easily with brush, spatula, extrusion gun or roller
  • Maintains flexibility and bond strength during extreme temperatures, weathering and stress
  • Yellow base and black accelerator
  • Mix ratio: 10 accelerator:100 base (by weight)
  • Nonvolatile content: 93 percent
  • Minimum application life: 24 hours
  • Assembly time: 48 hours
  • Typical cure time: 21 days
  • Specific gravity: 1.52 to 1.55 g/cc
  • Hardness: 45 to 50 Shore A
  • Service temperatures: -65 degrees Fahrenheit to 250 degrees Fahrenheit
  • Tensile strength: 260 psi
  • Elongation: 550 percent
  • Soluble chromate content: 4 to 5 percent
  • Repairability: 43 piw to itself and other MIL-PRF-81733D qualified sealants
  • Non-nutrient fungus resistance
Use Instructions
Mixing Instructions

Two Part Sealant: 1. Holding the cartridge, grasp the dasher rod and pull back approximately one inch.

2. 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.

Note: Do not inject all of the catalyst in one location. Distribute evenly throughout base material.

3. Repeat steps 2 and 3 until all the contents of the rod are emptied into the cartridge. Remove the ramrod.

4. Mix for the required number of strokes (hand mixing) or for the required amount of time (machine mixing) indicated in the kit intructions.

5. When mixing is complete, remove bottom cap.

6. Pull the dasher rod back to the neck of the cartridge, grasp the cartridge firmly at the neck, unscrew the dasher rod and remove.

7. Screw the nozzle into the cartridge, insert into the extrusion gun and use as required. For hand extrusion, press the used dasher rod against the

plunger to force the material from the cartridge.


The shelf life of AC-665 Class C is 9 months from date of packaging, when stored at temperatures below 80 degrees F in its original container.

Mixed AC-665 Class C may be stored under refrigeration as follows: 15 days at -10 degrees F, 30 days at -40 degrees F. It is important to remember that

freezing, storing and thawing procedures reduce application life. Also, frozen storage will reduce application life by varying amounts depending on the

storage temperature and length of storage time. All aspects of storage, freezing and thawing should be planned carefully and it is not recommended to mix

and freeze with less than 1/2 hour application time.

Health and Safety Precautions

AC-665 Class C sealant is safe to use and apply when recommended precautions are followed. Before using this product, read and understand the Material

Safety Data Sheet (MSDS), which provides information on health, physical and environmental hazards, handling precautions and first aid recommendations.

An MSDS is available upon request. Avoid overexposure. Obtain medical care in case of extreme overexposure.

CSNP-035 - Qualified
STM 40-112 - Qualified
MIL-PRF-81733 Type IV - C-12, C-24, C-48 Qualified
GAMPS 7115 - C-12 Qualified

Typical Physical and Application Properties

  • Color: Base - Yellow, Accelerator - Black

  • Mix Ratio: 100 base / 10 accelerator (by weight)

  • Nonvolatile Content: 93%

  • Base Viscosity (RVF Brookfield #6 Spindle @ 2rpm): 2,000 - 3,500 poise

  • Application Life and Cure Time
    (At 75 degrees F, 50% Relative Humidity)


  • Minimum Application Life*: 12 hours

  • Assembly Time**: 24 hours

  • Typical Cure Time***: 14 days

  • C-24

  • Minimum Application Life*: 24 hours

  • Assembly Time**: 48 hours

  • Typical Cure Time***: 21 days

  • C-48

  • Minimum Application Life*: 48 hours

  • Assembly Time**: 168 hours

  • Typical Cure Time***: 56 days

  • *Application life refers to the length of time that mixed compound remains at a consistency suitable for application with spatula or caulking gun.

    Application life is always measured at a standard temperature of 77 degrees F with a relative humidity of 50%. In general, for every 20 degree rise in

    temperature, the application life is halved; and for every 20 degree drop, it is doubled. High humidity levels during the mixing process will shorten

    application life.

    **Assembly time is the amount of time that a sealant will remain useable in a faying surface joint such that the sealant will allow excess amterial to

    squeeze out of joint to less than 0.004 inches.

    ***Cure time is defined as the length of time it takes AC-665 Class C sealant to reach 30A hardness. It depends on three factors: remaining application

    life, temperature and relative humidity. The temperature/humidity factors for application life also apply to curing. To accelerate the curing process,

    apply heat up to (but no more than) 120 degrees F.

    Typical Physical and Performance Properties of Cured Compound when tested per MIL-PRF-81733D

  • Color: Black

  • Specific Gravity: 1.52 to 1.55 g/cc

  • Hardness: 45-50 Shore "A"

  • Low Temperature Flexibility: No cracking, checking or adhesion loss when tested at -65 degrees F (-54 degrees C)

  • Thermal Stability, 48 hours at 250 degrees F: Does not soften, blister, crack or blow

  • Service Temperatures: -65 degrees to +250 degrees F (-54 degrees to +121 degrees C)

  • Tensile Strength: 260 psi

  • Elongation: 550%

  • Corrosion: Excellent protection from corrosion caused by galvanic coupling of dissimilar metals

  • Soluble Chromate Content*: 4-5%

  • Repairability: 43 piw to itself and other MIL-PRF-81733D qualified sealants

  • Fungus Resistance: Non-nutrient

  • *Not part specific

    View DetailsEnable JS
    Part Number
    3.5 oz Kit
    MIL-PRF-81733D Class 1, Grade A, Type IV-24
    Material Safety Data Sheet:
    Code: UN1866 | Class: 3 | Group: III - Click Here for Details
    View DetailsEnable JS
    Part Number
    Pint A+B Kit
    MIL-PRF-81733D Class 1, Grade A, Type IV-24
    Material Safety Data Sheet:
    Code: UN1866 | Class: 3 | Group: III - Click Here for Details
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