Complex sentence: After a protracted development period, the Swift entered service as an interceptor but due to a spate of accidents, its service life was short although a photo-reconnaissance variant did resolve some of the Swift's teething problems.
Split into simpler sentences: After a protracted development period, the Swift entered service as an interceptor, but, due to a spate of accidents, its service life was short. A photo-reconnaissance variant resolved some of the Swift's teething problems.