3M™ AC-350 Class B Aerospace Sealants

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3Mô Aerospace Sealant AC-350 is a family of intermediate density, fast-curing, polysulfide fuel tank sealants that provides outstanding resistance to aviation fuels and petroleum chemicals. The Class A, B and C variants maintain bond strength on many metal, composite and coated substrates and help meet a range of applications for integral fuel tank and fuselage sealing.

The 3Mô Aerospace Sealant AC-350 family of polysulfide sealants provide a number of advantages and benefits compared to traditional sealants. With three classes, they meet a wide range of manufacturing and maintenance needs.

Class Distinction
When Class A version is mixed, it provides a smooth pourable liquid that spreads evenly with a brush or roller to cover large areas quickly. Available in three different work lives, 3Mô Aerospace Sealant AC-350 Class A gives you the flexibility you need for various requirements. Rapid cure times keep your processes moving forward.

The Class B version mixes to a thixotropic paste that provides superb tooling properties when applied by injection gun or spatula. 3Mô Aerospace Sealant AC-350 Class B has no added solvents, which gives you more sealant by purchase volume and reduces the need for rework due to shrinkage. Available in multiple work lives, with rapid cure times, AC-350 increases your workflow flexibility.
  • Sealant resists aviation fuels and chemicals commonly used throughout the aviation industry
  • Various work lives and cure rates help meet a variety of process demands
  • Available in Class A, B and C to meet a range of requirements
  • Maintains bond strength on many metal, composite and coated substrates
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  • Application Life: 1 Hour, 15 Minute, 2 Hour, 30 Minute, 4 Hour, 6 Hour
  • Applications: Sealing
  • Brand: 3Mô
  • Capabilities: Aircraft Maintenance & Production Efficiency, Aircraft Sustainability, Aircraft Weight Reduction, Aviation Safety Enhancement
  • Class: A - Brushable, B - Non Sag
  • Color: Brown
  • Cure Type: Fast Cure
  • Product Form: Kit
  • Product Volume: 0.5 Ounce, 12 Ounce, 2 Ounce, 24 Ounce, 3.5 Ounce, 4.5 Ounce, 5 Gallon, 50 Gallon, 96 Ounce
  • Storage Environment: Room Temperature
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Our mechanics love this product, but the black color is hardly ever in stock. Please stock black!

Kenmore A
May 16, 2023

used for sealing fuel cell wiring on the side of the cell so it is almost always wet. 102 octane race gas that is fairly corrosive. easy to mix and apply. Has survived several weeks without any seepage

Randy K Verified Purchase

AC TECH AC-350 B-1/2 3.5 OZ KIT AMS-S-8802

May 21, 2022

Way easier and less messy than product from a can. Can easily be pumped into a syringe for precise application. Better nomenclature on cure times would be helpful. I had to google the B codes to figure it out. Maybe a real A&P would know.

Irving W Verified Purchase

AC TECH AC-350 B-2 3.5oz KIT AMS-S-8802

December 21, 2021

Seals like it should!

Elbert T Verified Purchase


November 30, 2021

Good product. Works as claimed by 3M.

Larry J Verified Purchase

3M AC TECH AC-350 B1/2 25G AMS-S-8802

June 16, 2021

This product is a great product. We have been using for years now and never have had a leak. This product is better that Teflon tape and paste.

Amerikal P Verified Purchase


June 8, 2021

This product works very well. Very fuel resistant ,flexible, and sticks excellent

Danny M
August 25, 2020

Been using these products for years. Its the best sealer for using on threaded fittings, better than Teflon tape and Teflon paste. When using these products fittings do not leak.

John B
November 15, 2018

The product was fine. However these products are packaged as individual containers of resin and hardener or as self contained Sem kits. There is no image presented for these, and no mention in the description regarding what you are getting.

Lee T
January 18, 2019


Please note, Aircraft Spruce's personnel are not certified aircraft mechanics and can only provide general support and ideas, which should not be relied upon or implemented in lieu of consulting an A&P or other qualified technician. Aircraft Spruce assumes no responsibility or liability for any issue or problem which may arise from any repair, modification or other work done from this knowledge base. Any product eligibility information provided here is based on general application guides and we recommend always referring to your specific aircraft parts manual, the parts manufacturer or consulting with a qualified mechanic.

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