Complex sentence: The NTSB also stated that despite the explosion caused serious damages to the engine cowling, the cowlings were all latched and didn't blown open, in which if it didn't then it could cause a massive drag force to the plane.
Split into simpler sentences: The NTSB also stated that despite the explosion caused serious damages to the engine cowling, the cowlings were all latched. None blowed outwards, in which if it did then it could cause a massive drag force to the plane.