Now, as for the comments by
tdracer, this has nothing to do with Maintenance carried out on the LOT aircraft, the routine replacement of the filters is not due until the a/c has reached 2000 FH, they are all short of that figure.
On the 787 (and 747-8) there is no 'scheduled' interval for filter replacement - fuel filter maintenance (at least per the MPD) is "on condition" based on the filter delta P measurement. Typical interval for fuel filters is around 2000 hrs, but brand new airplanes tend to go through the first filters well short of that (Boeing recommends 200 hours for the first filter replacement on the 747-8).
But consider this: So far, two airplanes have been found to be missing three (out of four) filters. Both belong to the same operator who has a grand total of two airplanes. No other incidents have been reported (and the number of in-service 787s is approaching 100). If this was due to 'random' error at Boeing, what are the odds that if only two airplanes were affected, they'd both end up at the same operator that (so far) only has two airplanes?
Plus, as I noted before, the 21.3 report indicates some pretty shoddy maintenance practices prior to discovery of the missing filters.