If it floated slightly nose down. And if it is hit by breaking waves at the reef edge it could get smashed into the coral in a nose down position. Cockpit debris falling out on the slope. Wings, engines, tail also getting smashed
The center section with its empty tanks may have been protected long enough to clear the surf until it sank far away.
If moored, some of the sections could have been prevented from washing away due to being tied down or the stakes or mooring lines snagging on the reef edge. A piece with a line attached could get hung up so some days it is hanging off the reef, underwater and other days it is washed up on the reef. Eventually it gets free and washes ashore or off the reef.
Could explain some of the aircraft debris being seen by some and not others, and also explain washed up debris found years later by Tighar.
And why no big pieces were seen and why little pieces may still be found.