Complex sentence: The missing seal caused frozen chunks of lavatory fluid to be ingested by the number three engine and damage the compressor blades, and, upon failure, the engine separated from the aircraft fuselage as it had been designed to do.
Split into simpler sentences: The missing seal caused frozen chunks of lavatory fluid to be ingested by the number three engine and damage to the compressor blades. Upon failure the engine separated from the aircraft fuselage, as it had been designed to do.