AS157 FAA-PMA Gray Silicone Adhesive Sealant – 3 oz for Aircraft Maintenance

Aerospace Sealants AS157 Gray Silicone Adhesive Sealant is an FAA-PMA qualified silicone sealant available in a convenient 3 oz tube, designed for aircraft maintenance sealing and bonding applications where a gray-colored silicone provides an aesthetically appropriate finish. The gray color naturally blends with aircraft aluminum structures, gray painted surfaces, and aircraft interior panels, making repairs less visually conspicuous.

AS157 cures through room-temperature vulcanization (RTV) to a flexible, durable silicone elastomer with excellent adhesion to metal, composite, glass, and rubber substrates. Its flexibility after cure accommodates structural movement, vibration, and thermal expansion and contraction without cracking or losing adhesion — providing reliable, long-lasting seals in dynamic aircraft applications.

The 3 oz tube format allows precise, hand-applied sealant placement for spot repairs, gasket applications, and small bonding jobs where cartridge gun equipment is not available or necessary. Its compact size makes it convenient for line maintenance operations and aircraft-on-ground repair work.

Technical Information

AS157 uses a one-component, acetoxy or neutral cure silicone rubber system that reacts with atmospheric moisture to form a cross-linked silicone elastomer at room temperature. The cured silicone retains its mechanical properties — tensile strength, elongation, and adhesion — over a wide service temperature range, providing reliable performance from cold soak at altitude to engine-heated zones on the aircraft surface.

The gray pigmentation in AS157 is achieved with stable, non-bleeding colorants that maintain their color integrity throughout the service life of the cured sealant, ensuring the repair remains aesthetically consistent with the surrounding aircraft surface. The pigment system does not adversely affect the mechanical properties or adhesion performance of the silicone formulation.

AS157 provides good chemical resistance to aircraft cleaning agents, hydraulic fluid mist, lubricating oils, and environmental exposure including UV radiation, rain, and humidity. For applications involving continuous fuel immersion, a polysulfide fuel tank sealant should be used instead, as silicone sealants are not intended for fuel tank interior applications.

Why Choose AS157 Gray Silicone Sealant?

• ✅ FAA-PMA Approved — Compliant for certificated aircraft maintenance
• ✅ Gray Color — Blends with aircraft structure for inconspicuous repairs
• ✅ 3 oz Tube — Ideal for spot repairs without cartridge gun equipment
• ✅ RTV Silicone — Flexible, durable cure at room temperature
• ✅ Wide Substrate Compatibility — Metal, composite, glass, rubber

Applications and Compatible Aircraft

AS157 gray silicone is used for aircraft interior panel sealing, fairing bonding, non-structural gasket sealing, electrical enclosure sealing, and general maintenance repairs on commercial, business, and military aircraft where FAA-PMA approved silicone sealant is specified.

Frequently Asked Questions

Q: Why is AS157 gray colored?
A: The gray color allows the cured sealant to blend visually with aluminum aircraft structures and gray-painted surfaces, making maintenance repairs less visually prominent on the aircraft exterior and interior.

Q: Is AS157 approved for fuel tank applications?
A: No. AS157 silicone sealant is not intended for aircraft integral fuel tank interior applications. For fuel tank sealing, use a qualified polysulfide or polythioether fuel tank sealant such as PPG PR-1422 or equivalent.

Q: What is the MPN for AS157 3oz tube?
A: The Manufacturer Part Number is AS157.

Q: Does AS157 require a primer or adhesion promoter?
A: In most aircraft maintenance applications, AS157 adheres well to clean, properly prepared metal and composite surfaces without a separate primer. Consult the applicable maintenance manual for specific surface preparation requirements for your application.

Q: What is the cure time for AS157?
A: AS157 cures at room temperature through reaction with atmospheric moisture. Tack-free time and full cure time vary with temperature and humidity — refer to the AS157 technical data sheet for specific cure schedule information.