Wesson, L., "Fusion Splicing Fiber Optic Cables in the Aerospace Environment," SAE Int. J. Aerosp. 5(1):133-150, 2012, doi:10.4271/2012-01-2109.
Successful use of fiber optic interconnects in high-performance platforms and applications depends on viable technologies for their repair and installation. Splicing is often desirable, either to repair a damaged interconnect or to install it, particularly where it is difficult or impossible to access all necessary locations for complete removal and replacement. However, reliable aerospace cable splices must endure conditions as adverse as those for which the original cable was specified. In addition, the splicing technology must be usable with a high degree of reliability under difficult aerospace working conditions. Mechanical splices have shown some promise for the repair of multi-mode aerospace fiber cables, but they face daunting difficulties in splicing single mode fiber cables, which are being ever more seriously considered for new and upgraded systems. Fusion splicing has long been accepted in the telecom industry for making the highest performance fiber splices, both single mode and multi-mode, but the technology has not yet been found adaptable to stricter aerospace requirements. Up until now the prevailing cable repair philosophy has been “remove and replace”, but in many cases this can be near-impossible and very expensive.This paper will describe new methods of in-situ repair of fiber optic cables using ruggedized fusion splicing machines. New fusion splicers can splice aerospace optical fibers in the field with near-zero insertion loss and unmeasurable return loss. Fusion spliced optical cables resist adverse environments and mechanical stresses with ruggedness approaching that of pristine cable. The new splicers, being ruggedized to satisfy MIL-PRF-28800F, can be used in most difficult-to-reach locations, virtually wherever a person's hands can work. Most recently, a new fusion splicer has been proven explosion-proof, suitable for use on fueled aircraft. SAE and commercial standards are in development to enable formal approval of the equipment for hazardous atmospheres. Extensive test data will be presented illustrating the new repair techniques on a variety of aerospace fiber optic cables, and a forecast of future development and transition to production will be outlined, particularly for commercial aviation.