The High-Dollar Consequences of Using the Wrong Sealant in Bonding & EMI Areas

Aircraft lightning-protection systems, EMI/RFI shielding features, and electrically bonded structures are all designed with one assumption in mind: the Correct Sealant is being used in the proper place. Sealants in these zones are not simple gap fillers; they are engineered materials that control electrical resistance, manage lightning-strike energy, maintain conductive paths, and prevent corrosion in some of the most demanding environments on an aircraft.

Using the wrong sealant can lead to catastrophic maintenance events, unnecessary component replacements, and mission-critical failures that cost tens or even hundreds of thousands of dollars. In extreme cases, such as lightning-strike zones or fuel tank interfaces, the wrong sealant can contribute to severe safety incidents.

This article sketches ten plausible, high-cost failures that result from the use of incorrect or non-qualified sealants in EMI, RFI, or lightning-protection areas. For each scenario, we highlight the correct PPG Aerospace/PRC-DeSoto product that prevents the failure and is available through GSA Advantage via Greenwood Aerospace.

1. Lightning-Strike Burnthrough on Composite Structures

When composite surfaces like radomes, winglets, fairings, and antenna housings are struck by lightning, the electrical current must dissipate smoothly across the structure; using a non-conductive or non-spec sealant interrupts that controlled path.

What Goes Wrong

The lightning energy concentrates at a discontinuity, causing localized heating, resin burnthrough, delamination, or damage to embedded conductive mesh. Radome replacements routinely exceed six figures, and downtime for military ISR assets can be far worse.

Correct Sealant: PR-1764 Class B

Engineered for lightning-protection environments, PR-1764 maintains conductive continuity, protects aluminum and dissimilar metals from corrosion, and withstands temperatures down to -43°F and up to 266°F. Its resistivity remains stable even after prolonged exposure to water or fuel.

2. EMI Shield Degradation Leading to Avionics Interference

Avionics bays, bonding straps, shield terminations, and RF enclosures rely on controlled electrical resistance between components. Even minor deviations can cause intermittent EMI issues.

What Goes Wrong

High-impedance joints cause display flicker, comm/nav dropouts, sensor noise, or mission system resets. Diagnosing EMI failures often leads to unnecessary LRU replacements long before a sealant mismatch is identified.

Correct Sealant: PR-2200 Class B

A rapid-cure, nickel-filled sealant designed for EMI/RFI shielding. It provides extremely low contact resistance (0.16 ohms), cures fast (approximately 6 hours to 30 Shore A), and remains stable up to 360°F intermittently. Ideal for avionics shielding and conductive bonding applications.

3. Fastener Blowouts After a Lightning Event

Lightning energy often travels through heavily torqued faying surfaces and fastener paths. If a non-spec sealant with too much electrical resistance is used, the fastener becomes the unintended point of energy concentration.

What Goes Wrong

A blown fastener can damage the surrounding structure, force the removal of multiple panels, and trigger mandatory lightning-strike teardown inspections.

Correct Sealant: PS-872 Class B

This aluminum-filled sealant is specifically engineered to maintain electrical continuity under high torque. It forms a resilient bond that preserves conductive pathways and prevents energy concentration at fasteners.

4. Fuel Tank Ignition Risks from Incorrect Impedance

Fuel tank interfaces, such as fasteners, panels, and bonding points, must withstand lightning energy exceptionally well. Wrong sealant equals wrong resistivity.

What Goes Wrong

An improperly sealed joint can arc under lightning conditions, creating a high-risk scenario in or near a fuel tank. Even a suspected arc track triggers extensive NDI, fuel system teardown, and panel rework.

Correct Sealant: PR-1764 Class B

Its stable electrical resistance and resistance to jet fuel exposure make it suitable for lightning-related interfaces around fuel systems.

5. Antenna Ground Path Failures

Antennas depend on low-impedance grounding to function correctly. A sealant that becomes resistive over time can disrupt RF grounding paths.

What Goes Wrong

Reduced nav/comm range, mis-calibrated sensors, intermittent ADS-B performance, degraded radar transmission, or false EGPWS/TCAS alerts.

Correct Sealant: PR-2200 Class B

Its combination of EMI shielding performance, corrosion inhibition, and stable electrical resistance makes it suitable for antenna bay continuity zones.

6. High-Resistance Faying Surfaces in Structural Assemblies

Faying surfaces, particularly torqued assemblies, must maintain consistent impedance even under mechanical stress, thermal cycling, vibration, and fuel exposure.

What Goes Wrong

An incorrect sealant leads to elevated resistance, which means the aircraft fails bonding tests and meets grounding requirements. Repeated troubleshooting and disassembly follow.

Correct Sealant: PS-872 Class B

Purpose-designed for torqued faying surfaces with conductive requirements. Retains conductivity after fuel exposure and temperature cycling.

7. Lightning Diverter Strip Malfunctions

Diverter strips rely on the underlying structure and sealant system to provide uniform conductivity. Using the wrong sealant can alter dielectric properties or cause an unintended high-resistance spot.

What Goes Wrong

Lightning energy bypasses the diverter strip entirely and strikes the radome or nose structure directly. Radome replacement costs often exceed $100,000 in parts alone, let alone man-hours. 

Correct Sealant: PR-1764 Class B

Formulated for lightning-protection applications and maintains electrical continuity across composite and metallic surfaces.

8. EMI Leakage in Avionics Bays

If conductive joints in EMI-sensitive compartments are sealed with a non-conductive or poorly cured material, the shielding enclosure loses effectiveness.

What Goes Wrong

EMI leaks from high-power wiring or mission systems into other avionics, causing intermittent, hard-to-trace failures. Aircraft may be grounded while technicians hunt a ghost.

Correct Sealant: PR-2200 Class B

Provides exceptional EMI/RFI shielding, with a robust electrical profile even after fuel immersion and thermal aging.

9. Moisture Intrusion and Galvanic Corrosion in Lightning-Critical Structures

Lightning-zone surfaces experience intense heating and electrochemical stress. If the sealant is not corrosion-inhibitive and correctly conductive, corrosion begins immediately.

What Goes Wrong

Corrosion under a faying surface or bonding joint leads to grounding failures, structural degradation, and expensive rework, often requiring complete strip-and-replace operations.

Correct Sealant: PS-872 Class B

Combines corrosion inhibition with lightning-strike continuity, providing long-term protection against galvanic couples.

10. Paint System Failures in Conductive Zones

The wrong sealant chemistry can cause topcoat blistering, fisheyes, or poor dielectric transition, especially near conductive meshes or lightning-diverter interfaces.

What Goes Wrong

Paint repair may look cosmetic, but in a lightning-critical zone, the dielectric layer is part of the electrical design. Incorrect dielectric thickness or adhesion can compromise lightning performance.

Correct Sealant: PR-1764 Class B

Its stability across a wide temperature range and compatibility with aircraft materials make it a safe choice in regions where conductivity and coatings coexist.

Why Procurement Teams Rely on Greenwood Aerospace

Selecting the right lightning-protection or EMI-shielding sealant is not just about compliance; it is about safeguarding multi-million-dollar aircraft assets. Greenwood Aerospace provides:

  • Fast availability through GSA Advantage

  • Direct support for military and federal aviation programs

  • A deep catalog of PPG Aerospace conductive and corrosion-inhibitive sealants

  • ITAR compliance, AS9120B certification, and decades of experience supporting sustainment operations

When applications involve EMI shielding, grounding, bonding, or lightning-protection zones, choosing the Correct Sealant is essential. Greenwood Aerospace guarantees that you get the right product, every time.

Other Greenwood Aerospace Services

Greenwood Aerospace is much more than just a GSA Advantage vendor. 

Greenwood Aerospace offers military and government clients procurement options, including for international clients, for contracting, logistics, and distribution services tailored for urgent and long-term programs. 

We also leverage our proprietary software suite, GPIQ, to manage supply chains, from sourcing parts and mission kits to small-part support. We support ITAR-registered contracting and FMS capabilities for U.S. and U.S.-allied nations. 

Greenwood Aerospace is registered with the U.S. Department of State as an ITAR-compliant supplier, allowing us to support major defense contractors with the secure handling and export of ITAR-regulated materials. Our credentials include UEI KVSUYYSJS174, DUNS 604006874, CAGE Code 2Y735, AS9120B quality management certification, and ITAR DDTC export compliance. We operate under multiple NAICS codes, including 488190, 336413, 332722, 336411, 481212, and 532411.

Contact Us!

For all GSA-related inquiries, including order support, availability checks, or urgent procurement needs, contact us at gsasales@greenwood.aero, 580-865-6000, or 833-GSA-EBUY (833-472-3289).

All other inquiries should go to our main contact lines: email contact@governmentprocurement.com or phone (580) 762-2580.