If you run a quick Google search about Boeing's lightning protection system for the 787, you may be surprised to discover that there isn't a whole lot of information out there about it. The system, which involves a wire mesh embedded in the 787's composite fuselage, is proprietary and as such, Boeing has been rather quiet about the details.
What will be clear in the not too distant, however, is the "special condition" that US FAA officials intend to issue for the 787 concerning lightning protection. This will clarify requirements that must be complied with before the twinjet can be certified. Special conditions concerning HIRF (high intensity radiated fields) were issued last year.
In May, 787 programme manager Pat Shanahan said Boeing and the FAA have found a "path forward" to resolve lightning protection issues.
Boeing now explains: "There has been good communication between Boeing and the FAA as the special condition has been developed and they are not a surprise to us. They are not a result of any specific 787 design concern or feature.
"It will be the FAA's responsibility to make the finding of compliance for the 787. Our job is to define the design in a manner that we are confident will meet these requirements. We do not know when the special condition will become final."
Boeing says its system "is primarily there for economic reasons to reduce the effects of lightning damage on the fuselage to minimize the impacts to customer airlines".
It notes that the extremities of the aircraft, such as wing tips, engine nacelles, horizontal stabilizer and tail are other areas where lightning is expected to attach "but they utilize other methods of protection based upon the expected lightning threats in those areas".
"These areas primarily use metal foils similar to past models as the major protection method rather than the wire mesh. The design focus for the wings is not as much on structural damage but on protecting the fuel tanks and the wire mesh provides less benefit there."
Boeing says it understands "the requirements that the design must meet for certification" and is confident it will achieve certification.
For more information on how one might protect composite-body aircraft from lightning, check out Arthur Hawley's invention here.