I have recently purchased the Besra in GTA story mode playing as Michael but it does not appear in my hanger and have ended up buying it twice now!! I would also like to ask if once your plane has been destroyed is it still accessible in your hanger?
Your plane (Besra) should be in the airfield that you own, there is a glitch that sometimes sends the plane to Sands Shores Airfield. You might even find both of your planes there. Other players have also said that sometimes it takes 10 minutes to 3 hours for your plane to "arrive" almost all players says that their planes eventually arrived (or they stumbled on it at the sandy shores one) All I can say is just be patient and it should come... eventually. If the plane that you bought crashes, it will end up in the airfield it arrived in.
Good Luck on getting your plane ~Kingsley