Speckulater is correct. Also, it is normal for work on aircraft to be done concurrently with other certification tasks, including the FAA's certification team reviewing the manuals for appropriate content, crew training, etc. - it is a smart move on Baltia's part that they are actually using an FAA Designated Airworthiness Representative to oversee the maintenance work & modifications, as it will save time.
Keep this in mind - the FAA has within the recent past made many changes to its certification process, including a serious, comprehensive audit system that the applicant must complete. They have also imposed this complex audit system requirement on all existing carriers, and are doing so in steps - major airlines are having to dedicate unprecedented resources to meeting this new standard, and are finding it very difficult.
As a result of this requirement, Baltia is completing the most arduous certification process ever completed by any new airline. I commend them for making good progress under such circumstances - it is clearly a reflection of their having the right people doing the job.
