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3M Aerospace AC-236 Class B-1/2 Fuel Tank & Fuselage Sealant

3M Aerospace AC-236 Class B-1/2 Fuel Tank & Fuselage Sealant

Seal integral fuel tanks, repair integral fuel tanks and seal fuselages with the use of 3M Aerospace AC-236 Class B-1/2 fuel tank and fuselage sealant from SkyGeek. This sealantís formula consists of a two-part manganese dioxide-cured, liquid polysulfide polymer compound. This thixotropic paste can be easily applied through the use of an injection gun, extrusion gun or spatula. Use it on aluminum, stainless steel or steel surfaces. This product remains flexible with a strong bond when used with most metal substrates. Once cured, AC-236 resists chemicals, petroleum products, jet fuel and aviation gasoline.

Approvals, References and Specifications
  • AMS-S-8802
  • FMS 1049
  • 299-947-074
  • LES 1039 BU
  • HS 12373
  • BS 25146
  • WL 5.5902
  • DTD 900/6147
  • STRYP 5960


  • Two-component, manganese dioxide-cured, liquid polysulfide polymer fuselage and fuel tank sealant
  • Use to seal integral fuel tanks, repair integral fuel tanks and seal fuselages
  • Resistant to jet fuel, aviation gasoline, chemicals and petroleum products
  • Retains flexibility and bond strength with many metal substrates
  • Use with aluminum, steel and stainless steel
  • Lasts through stress, weathering and extreme temperatures
  • Easily applied thixotropic paste with spatula, injection gun or extrusion gun
  • Excellent tooling properties
  • Service temperature range: -65 degrees Fahrenheit to 250 degrees Fahrenheit
  • Color: Base - white, Accelerator - black
  • Mix ratio: 100 base:10 accelerator (by weight)
  • 97 percent non-volatile content
  • Minimum application life: Ĺ hour
  • Typical tack-free time: 8 hours
  • Typical cure time: 24 hours
Use Instructions
Two-Part Sealant Cartridges:

  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 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 instructions

  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-236 Class B is 9 months from date of packaging, when stored at temperatures below 80 degrees F in its original container.

Mixed AC-236 Class B 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 half an hour application time.

Health and Safety Precautions

AC-236 Class B 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 on request. Avoid overexposure. Obtain medical care in case of extreme overexposure.

AMS-S-8802 - Qualified
FMS 1049 - Qualified
299-947-074 - Qualified
LES 1039 BU - Qualified
HS 12373 Rev A - Qualified
BS 25146 - Qualified
WL 5.5902 - Meets requirements
DTD 900/6147 - Meets requirements
STRYP 5960 - Meets requirements

Typical Physical and Application Properties

  • Color: Base - White, Accelerator - Black

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

  • Nonvolatile Content: 97%

  • Base Viscosity (RVF Brookfield #7 Spindle @ 2rpm, 77 degrees F): 9,000-14,000 poise

  • Accelerator Viscosity (RVF Brookfield #7 Spindle @ 10rpm, 77 degrees F): 700-1600 poise
  • Application Life and Cure Time
    (At 77 degrees F, 50% Relative Humidity)


  • Minimum Application Life*: 1/2 hour

  • Typical Tack-Free Time**: 8 hours

  • Typical Cure Time***: 24 hours
  • B-2

  • Minimum Application Life*: 2 hours

  • Typical Tack-Free Time**: 24 hours

  • Typical Cure Time***: 48 hours
  • B-4

  • Minimum Application Life*: 4 hours

  • Typical Tack-Free Time**: 36 hours

  • Typical Cure Time***: 90 hours
  • *Application Life refers to the length of time that mixed compound remains at a consistency suitable for application with roller or brush. Application life is always measured at a standard temperature of 75 degrees F with a relative humidity level of 50%. In general, for every 20 degrees F 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.

    **Tack-free Time is the length of time after which a mixed sealant will no longer tightly adhere to L-LP-690 standard low density polyethylene film.

    ***Cure time is defined as the length of time it takes AC-236 Class B sealant to reach 30A hardness. It depends on three factors: remaining application life, temperature and relative humidity. To a certain extent, the temperature/humidity factors for application life also apply to curing. To accelerate the curing process, apply heat up to (but not more than) 120 degrees F.

    Typical Physical and Performance Properties of Cured Compound After 14 Days at 77 degrees F / 50% Relative Humidity (when tested per AMS-S-8802)

  • Color: Gray

  • Specific Gravity: 1.64

  • Hardness: 60 Shore "A"

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

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

  • Thermal Rupture Resistance: Does not blister or sponge

  • Corrosion: None

  • Fuel Resistance: 70 days at 140 degrees F, 35 piw/100% cohesive failure

  • Repairability: 40 piw to itself and other AMS-S-8802 qualified sealants

  • Resistance to Other Fluids: No cracking when bent 180 degrees over a 1/8" mandrel. No more than 6% loss of the sealant compound after fluid immersion

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    Country of Origin: USA
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