The fastener joint is one where a fastener is used to join two pieces of hardware together and FAA requirements for EME protection as part of Part 25 Secton 954 and 981 require all joints and fasteners to be installed in a way that prevents any sparking within the fuel that could lead to a catastrophic ignition. Boeing has had to meticulously design the metallic parts in the aircraft, including the incorporation of an elaborate current return network, to prevent sparks and arcing, as well as withstand lightning strikes.
While removing and reapplying sealant to each 787 remains critical in preparing for delivery, the workmanship of its application is not the only item Boeing has identified for change inside the aircraft's composite wings; a design change discovered in the fall of 2009 requires the removal and replacement of thousands of improperly coated fastener joints to ensure the majority-composite jetliner's protection from lightning strikes.
The removal of the sealant will allow access to the thousands of wing fuel and hydraulic system fastener joints which were designed and installed with an improper coating, and have to be removed and replaced to meet US Federal Aviation Administration requirements for electromagnetic effects (EME) protection for lightning strikes.
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