Self-Sealing Fastener Technology for Reduction of Hazardous Materials

WP-201011

Objective

Most fasteners used in aircraft structures are hand-coated with sealant before installation. Specifically, this "wet" installation process seals moisture out and fuel in (as in integral fuel tanks) and provides critical protection against galvanic corrosion. In the current fastener wet installation process, a trained technician begins either by mixing a two-part sealant or by thawing a batch of pre-mixed frozen sealant, each having a limited work life and shelf life before it must be discarded as hazardous material (HAZMAT). The sealant is applied to each fastener, the fastener is installed, and excess sealant around the fastener head is removed using solvent. This process generates HAZMAT in the form of solvent and mixed sealant that has exceeded its work life. The process is also expensive, time consuming, and subject to technician error. In addition, removal and replacement of wet installed fasteners by field and depot technicians is labor intensive, leading to increased downtime for aircraft repairs. This project will demonstrate and validate the QwikSeal technology in an effort to eliminate the use of separately applied sealant for meeting the severe performance requirements of military aerospace operational environments.

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Technology Description

The QwikSeal technology successfully pre-applies sealant to standard aerospace fasteners and includes a proprietary method for blocking the cure of a two-part sealant resin after mixing, effectively converting it to a one-part moisture-curable system that can be pre-applied to fasteners. It involves a solvent-free, ultraviolet (UV)-curable size coat chemistry with extremely low moisture permeability that can be cured to a frangible state using UV radiation without degrading the cure-blocked sealant over which it is applied. This can be applied to any fastener and will provide the same or better level of corrosion protection and performance as found today but without the level of sealant waste from the present process.

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Benefits

Precoated fasteners using the QwikSeal technology will reduce the amount of sealant used, and ultimately disposed of as HAZMAT, by 70%. Since there is minimal sealant squeeze-out using QwikSeal fasteners, use of cleaning solvents will also be dramatically decreased. Combined, the result will be the elimination of almost 1 million pounds of HAZMAT annually and roughly $1.06 million in disposal costs. With the sealant pre-applied to the fastener, there will be a significant labor savings as well from eliminating the application of sealant to each fastener. (Anticipated Project Completion - 2013)

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Points of Contact

Principal Investigator

Mr. Alan Fletcher

Air Force Research Laboratory

Phone: 937-255-7481

Fax: 937-656-4419

Program Manager

Weapons Systems and Platforms

SERDP and ESTCP

Document Types

  • Fact Sheet - Brief project summary with links to related documents and points of contact.
  • Final Report - Comprehensive report for every completed SERDP and ESTCP project that contains all technical results.
  • Cost & Performance Report - Overview of ESTCP demonstration activities, results, and conclusions, standardized to facilitate implementation decisions.
  • Technical Report - Additional interim reports, laboratory reports, demonstration reports, and technology survey reports.
  • Guidance - Instructional information on technical topics such as protocols and user’s guides.
  • Workshop Report - Summary of workshop discussion and findings.
  • Multimedia - On demand videos, animations, and webcasts highlighting featured initiatives or technologies.
  • Model/Software - Computer programs and applications available for download.
  • Database - Digitally organized collection of data available to search and access.