Complex sentence: The A- 12 took off from Kadena at 1400 that day for a routine functional check flight on the just-installed starboard engine, flying towards the Philippines and a long turn back towards Kadena.
Split into simpler sentences: The A- 12 took off from Kadena at 1400 that day. It was to be a routine functional check flight on the starboard engine that had just been installed in the aircraft, by flying towards the Philippines and then a long turn back towards Kadena.