Delta announced in a press release that it will reduce fall capacity by 1.4 percent by removing 10 aircraft from scheduled service. They're going to retire seven 727s; "...an additional three aircraft will be removed from the schedule to support various maintenance modifications and operational requirements," according to the press release.
MY QUESTION, and it's one out of idle curiosity, believe me: Does anyone know what type(s) of aircraft the other three aircraft are, and (this is pushing it) what kinds of "maintenance modifications" Delta plans on performing on these aircraft to necessitate them being out of service for the fall schedule?
I'm sure it's probably SOP; I'm just curious about what a/c are being removed and what's being done to them. Any informative answers would be appreciated.