Aircraft Phase-In
When an aircraft (new or used) is first delivered to an operator, the airline itself (or its maintenance partner) must record all details of Part Number, Serial Number, Maintenance Planning Document (MPD) schedule for all components within its maintenance planning and control system. This will also include details of the Flight Hours (FH)/Flight Cycles (FC) undertaken to date by each component, plus the lives already consumed on all installed life limited parts (LLP’s). An Aircraft Phase-In is a particularly extensive task in the case of a used aircraft requiring a large amount of time and resources

(the opposite is "phase-out")

http://jagaviationgroup.free.fr/management_of_the_aircraft_p...

http://www.srtechnics.com/cms/index.asp?TopicID=214

http://www.airworthiness.fr/index-2-3.html